FYI Essential M119 Ignition "Tune Up" mods [Distributor cap vent / slot]

[JC220]

Hi all,

I have been meaning to address this on my little used 500E for years.... it is a problem I myself recognised about 5 years ago when I first looked at an m119 distributer cap..... Compare to any other distributor cap of the era such as an m104 and you will see there are NO ventilation slots at the top or top sides of the m119 caps. That and some other parts now aged / defective add to your woes!

This thread is not intended to be all encompassing. It is not getting bogged down into the ifs or whys. It is simply a straight forward and to the point thread to show what every m119 engine with distributor caps needs done to it now in order to provide reliable service. My own 500E farts, coughs, had extended cranking at times and has died on the road before due to this m119 problem.

Here is what her caps looked like when removed:



The A typical m119 cap contamination. Here is what I did today:

First make a reference mark on the top point of your caps. (I know my caps are recent new less than 1k miles in my ownership so I am re-using them)



Check if your ignition cables are fitted with number labels. Mine were not so I used a paint marker. This is concealed anyway by the engine covers and makes it very clear. Note that the caps are marked L# + R#. So you look at the cap and mark the cable based on which side of the motor the cap is fitted as viewed from the drivers seat.



Remove the caps, rotors and rotor arm brackets.



Now remove the old cam seals. Since my 500E has recent new cam cover gaskets etc I chose to replace these in situ. (You could also pull the cam covers, power steering reservoir and front head covers if any if those are leaking)

To remove the old seals, punch one side inwards slightly then use a hook implement in order to pull out the seal.





I cleaned up the rust from the cam shaft with fine sandpaper, wd40 and scotchbrite. Fiddly but important.





Next get your new seals ready. Lube the inside rubber with grease and be very careful that you start the lip on square and gently or the spring can pop off the back of the radial seal! I also use a non setting loctite brand gasket dressing on these radial seals and a large washer then socket to press home. You would want about 6 inches of m6 stud to do this more easily.






Clean all areas with brake cleaner and Next part is mods and re-assembly

EDIT- Before you start please do read the thread below:

This is another documented problem area whereby the bolts strip out. See post #15 below also!

Stripped bolt heads on distributor rotors: How to remove?? HELP | M119 Engine

Hi guys, I tried to replace my old rotors and could not do it :hammerhead: It is 3 mm hex but it spins inside of a bolt (either bolt was crap or it was too tight) anyway now tree bolts are completely gone:pissed: , they are round inside instead of angular 3mm hex. :fun: So ... any ideas how...

www.500eboard.co

 

[JC220]

You want NEW insulators. Unless you KNOW you already replaced these in the past couple of years go ahead and fit new ones even if the old ones look OK. They are known failure points and the micro cracks may not be visible to your eye.



Personally I spray some WD40 on the head area behind where these insulator cups fit. Water Displacement formula 40 is ideal for this use but if you don't want to use it skip this step.

Fit the new insulators in place and install the rotor arm brackets with a tab of blue loctite on the threads.



Clean the rotor arm contacts and re-install again with a very small drop of loctite.



Now for the caps - pre mods:



Remember those reference marks made before disassembly at the top most part of the caps? I cut 3 slots there and 2 more sets additional at 10 and 2 o clock positions. This is a crucial modification in order to allow atmospheric or other moisture to vent and escape from the distributer caps. I also cleaned the terminals gently with electrical cleaner and a fine scotch pad.



Demonstration using an old insulator cup to show how these slots will allow moisture to pass the O ring:



Refit both caps, make sure all cables are back on the correct spot and tight and put all covers back on.

My 500E cranked right up and is running fantastic today. Time will tell if this will solve her ignition problems but I believe this is as good as it gets and it will now be able to vent the moisture and run properly.

Worth noting also that the m119 runs better with a 1mm spark plug gap VS the factory 0.8mm spec. So if unsure, buy a new set of plugs and make sure they are gapped at 1mm for best running.

That's it, you should have many years reliable service from your distributor cap m119 if you followed each step!

 

[JC220]

Sorry for the lack of quality here! I do not have time for a full proper, all singing all dancing How-To so it was this or nothing.

What we have achieved here is:

WD40 to help displace condensation forming on the heads behind insulators.

New cam seals to prevent/ reduce oil or blow by gas contamination of ignition components.

New insulators to ensure they are preventing any ignition leakage.

Provided ventilation slots in the caps at 10, 12 and 2 o clock positions to allow any condensation to escape.

Reminder on the 1mm spark plug gap.

This should end any cutting out, misfiring or extended cranking on your m119

 

[smilecenterlab]

great information.how do you cut the slats? saw,dremel tool?

 

[JC220]

great information.how do you cut the slats? saw,dremel tool?

Yes you could use a Dremel, I used my grinder with a thin cutting disc. I wasn't terribly worried about extreme accuracy since they are not visible, there to do a job and the caps are consumable parts also.

 

[Jlaa]

Thanks so much for this guide - particularly w/ the photographs on replacing the cam seals.

 

[JC220]

Thanks so much for this guide - particularly w/ the photographs on replacing the cam seals.

No problem- the w140 cluster hook tools are great for that application (and many others!)

 

[Duh_Vinci]

Joe, great, all inclusive guide to everything one need with the visual, appreciate it!

Regards,
D

 

[luckymike]

Oh my gosh. I just did this cap mod Friday. Started with just the right side as a test. We'll have to compare notes over time.

 

[robm.UK]

... It is simply a straight forward and to the point thread to show what every m119 engine with distributor caps needs done to it now in order to provide reliable service.

Good to see you’re promoting my distributor cap fix

You can download my article on moisture related misfire by clicking the link -> HERE <-

I note that you have made some departures from my recommendations, which at best may not work out for some folks, and at worst may lead to the wasted effort and expense of others. So I feel compelled to point out the following: -

NOT every M119 will require the distributor cap modification. Only those possibly in States/areas where the climate has a high humidity, low ambient temperature, and a dew point that is close to that temperature. This rules out Nevada, Wyoming, Arizona, Utah...

A few months back I posted the diagram below which proposes a risk map of moisture related misfire for some areas of Europe and the US: -

My own 500E farts, coughs, had extended cranking at times and has died on the road before due to this m119 problem.

As I wrote in the above article, the distributor mod only ‘tilts the balance’ in favour of more normal running, no more, no less. The problem is that there are other factors that can elicit similar symptoms, such as other fuelling or ignition faults, air flow calibration, ignition timings, manifold depression, air leaks, fault CTS etc etc. Prime of which probably is fuelling and the tendency (by design) for the Bosch system to run lean, even at WOT. This tendency increases as the car’s get older due to wear, contamination and acidification due to the use of ethanol fuels. But this is for another thread

For an effective tune up mod, along with the distributor mod (if necessary) I also recommend that the fuel trim and AFR is mentioned and checked, and if necessary adjusted to correct for any excessive leaning out, which is very likely in an older car as this affects cold start, idling and WOT performance.

... I cut 3 slots there and 2 more sets additional at 10 and 2 o clock positions. This is a crucial modification in order to allow atmospheric or other moisture to vent and escape from the distributer caps...

View attachment 135183

I can see that you are recommending fewer vents. This is probably unwise, since the advantages of the additional vents outweigh the small amount of effort to cut them.

I propose that in inclement climatic conditions (those areas in red and blue regions) the moisture content inside an unmodified OEM distributor, while the engine was warm and running, is roughly 3%. This is sufficient to cause misfiring. (4% moisture is what you would typically expect by the sea).

I wager that a modified cap with slightly fewer vents like yours would reduce the moisture content to 2%, which is still sufficient to cause misfire, as I have already tested this scenario and found it failed.

It is only with the recommended vents shown in my photo below that I would be confident in reducing the moisture content to 1%, which is just enough to stave off the moisture related misfire.



The other thing that I notice from your photo is that you have not modified the existing vents. These ought to be cut so that the air flow goes from this: -



To this



You can see where I have cut over the top of the existing vents to promote air flow and moisture dispersion.

Demonstration using an old insulator cup to show how these slots will allow moisture to pass the O ring:


View attachment 135184

So, I can see from you photo above that the slot vents are probably not deep enough to promote sufficient air flow. I recommend that the slots ought to be cut at least 1.5mm into the black polypropylene interference cover as per my article. See below: -

... Worth noting also that the m119 runs better with a 1mm spark plug gap VS the factory 0.8mm spec. So if unsure, buy a new set of plugs and make sure they are gapped at 1mm for best running.

Hmmm... is this wise? I am not sure. A wider plug gap means a higher kV demand, shorter firing time and increased load on coil. This condition increases with load. It also increases with a leaner mixture, which prevails when these cars get older.

I suppose it is true because you wrote it. But before doing this I would make sure the fuel trim is ok first of all, and take a coil output (parade pattern) trace with a scope before and after just to be sure.

 

[gsxr]

Hmmm... is [a 1mm spark plug gap VS the factory 0.8mm spec] wise? I am not sure. A wider plug gap means a higher kV demand, shorter firing time and increased load on coil. This condition increases with load. It also increases with a leaner mixture, which prevails when these cars get older.

The wider gap has been recommended by several different MB technicians, as a cure for a hot-idle misfire caused by too small of a spark with lean mixture. The ignition system used with LH injection is robust and has no problems firing across a wider 1.0-1.1mm gap. If you search the forum you'll find threads from many years ago with more detailed explanations. I believe this was also recommended for M117's as well?

 

[JC220]

Sorry @robm.UK, this is my own thoughts on the subject! I am not using your report

Note that I posted many thoughts and carried out my own testing on the need for m119 cap mods WELL before your report ever existed. Indeed on this very forum....

See below. Not getting into a pissing contest with you or anyone else mind you, people can make up their own minds.

Thread is supposed to be helpful info only for members.

I can back up my claims per my old posts below FYI

My 500E was put away for winter in my carport. Rather than cold startups etc I choose to let the car hibernate and start her up this evening for a first drive of the year.

Fired up right away as always- perfectly smooth. Drove it to a filling station a mile away and half filled tank with fresh super unleaded. Cranked up fine and drove off on up the road.

Next junction around 5 miles later- pop fart dead. Stone dead. Cranking and popping that was all. Pushed her off into a hard shoulder and phoned GF to come get me (to get tools at home) whilst my brother who happened to be with me stayed with my 500E.

Came back 20 mins later - pulled the dist caps and they were laced with water condensation inside. (My very first suspicion is that it was dizzy cap related) All leads, plugs, caps and rotors are brand spank new less than 100 miles on them - fitted about a year ago.

Dried out the moisture with a cloth, sprayed WD40 inside the cap and in the rotor area as best I could - problem solved. Drove home as is nothing happened. Some WOT action confirmed I was on all cylinders again with a puff of tyre smoke.

Lesson? If your 500E is stored outside or in less ideal conditions for months on end it would be prudent to check moisture before first trip out. Dont take cold start behaviour as a given - if moisture is in there it will show its face after 10 or 15 mins of driving.

Lesson no 2 - always have a rag, 5mm Allen wrench and a small can of WD40 in your 500E's trunk.

I will monitor this and keep checking caps periodically and apply WD40 each time to displace moisture from in there.

The picture was taken at the side of the road with the moisture I found in RH bank cap. Both were the same level.

Sucks breaking down - especially in a gleaming 500E! I'll not lie - it pissed me off, imagine how good a 500E would be with coil packs....... dont like distributors and my other HFM models never miss a beat. The 500E will have to gain my trust again somewhat
View attachment 82117

Location of cap described in my post above! (Read post #42 fully PLZ…..)



Makes no difference to this issue how fast the engine warms up IMO……

I have my own theory on this issue. We know that behind the insulating cups is an alloy section of the cylinder head. The coldest surface in this assembly due to the thermal mass of the alloy head material. This area is also not sealed from the distributer cap – due to the hole recess (In the insulating cup) to allow the rotor arm mount to pass through and that the cup is freely floating against the head (No seal) and only seal is an O Ring to the distributer cap. This distributer cap O ring seal is more locating function than seal and this is confirmed by the fact the Distributer caps have vent slots in them at this O Ring seal junction.

Remember that it is very typical in this problem for the car to cold start just fine – then at a certain warm up stage start to stumble / cut out….. Correct? Which was exactly my situation yesterday.

I believe that atmospheric moisture readily makes its way in behind said insulator cup and condenses on the aluminium head. This is also where people primarily see liquid spotting on the back of the insulator cups. Then as the motor begins to warm up this moisture is displaced / evaporates / moves into the distributer assembly to the next coldest surface – the inside of the plastic distributer cap and condenses again causing the misfiring / stumbling.

Yes the insulator cup(s) itself can be defective / have micro fissures perhaps – but that is NOT the case in my car as the photo proves with excess moisture sitting inside the distributer caps to the point the car was dead – where it ran 100% perfect minutes previously at cold startup. (The moisture was NOT on the underside of the distributor caps at startup is what I am pointing out!)

So to me the void behind the insulating cups IS the primary weak point. And I am trying to think of a material to seal / fill that void - foam would need to be applied carefully and possible hazard due to the engine temps. Unless I use Pink Fire rated foam…….. a bead of RTV won’t be enough either there will still be void space. I also want to avoid a situation of glueing or adhering the insulating cups to the head wherever possible. I would place a tube inside the rotor hole area to protect the cam oil seal ring from the pink fire rated expanding foam. For those wondering about the foam – yes it will clean off and dissolve with appropriate cleaners should I wish, and have a backup new pair of insulting cups on the shelf for this experiment – to swap back in if required.

WD40 is bashed on most forums since it is a less than ideal lubricant. Lashing WD40 inside the distributer caps is a temporary solution at the moment which after all is exactly what that product is most suitable for (Water Displacement 40th Formula) Has anyone used WD40 before in the M119 caps? It does work………. It was my brother who suggested it yesterday, he is a top fuel crew chief and uses it on the Mags when the dragster is stored outside overnight before racing. The WD40 spray layer will not last indefinitely, indeed it may only last a few weeks and evaporate off but whilst that coating is inside the caps the water condensation cannot condense and cause issues. Moving forward, foam or not I also intend to upkeep the WD40 spray inside the caps as additional protection.

EDIT- further reading on TFTSNBN M119 distributor caps.. moisture!!

PS I have my own ideas and theories developing on this issue ranging from how any vapour can escape from the caps etc and I will create a new full thread of my own

Gerry, your experience will vary! Indeed every member’s experience can and WILL vary since we are all over the world. Some other factors:

• Humidity levels and ambient temperatures in your area
• How frequent the car is fully warmed up driven
• How the car is stored – outside – inside - and the temperature / ventilation conditions of said storage
• Condition of the Ignition system
• Condition of camshaft oil seal rings
  • 
    My 500E has never suffered this water vapour in caps before in just over 3 years of ownership. I believe this is because it was always stored inside in my dry, heated, double glazed and fully insulated garage attached to my home. (Optimum conditions VS outside in a carport with 2no open ends like recent months)
    
    I believe that this problem is only now occurring because my storage conditions through winter have changed and the car sat dis-used for longer periods. Therefore my 500E was suddenly within the scope of the set of parameters that this issue can occur within.
    
    To say that because one members car never had this fault, is not to say that it could not be an issue with other people’s cars. IMHO – and respectfully.
    
    
    
    Very likely the same reasons stated above. IE; when these cars were new they would have been driven alot more frequently throughout the year whereas now among the other factors (EG: aging ignition system) we have 500Es that are generally, for most members - second or third cars. Cosseted classics in other words, that see long periods of dis-use like winter storage compounding the problem where (un)favourable conditions exist for the problem to occur.
    
    
    
    
    I agree Dave – the O rings here do little to nothing at all. Merely a dust guard of sorts.
    
    
    
    
    
    
    Removing and renewing ignition components will of course give temporary reprieve from this moisture buildup problem. Because you are drying out the area and fitting new clean parts before the slow cycle starts all over again in the coming weeks – months. Your description aligns exactly with my thoughts on this subject.
    
    
    My experiment was carried out and see the photos below. I had 4x clear paint pots with equal amount of fluid in a shot glass in all 4x.
    
    View attachment 82128
    • 1st was control (Uncut)
    • 2nd had a bottom cut only – like M119 caps essentially
    • 3rd had top only cut
    • 4th had both bottom and top cuts.
    
    Notice when looking at the following pictures what happens:
    
    Control is reaching saturation levels- as expected:
    
    View attachment 82129
    
    Bottom cut only- pretty close to the control. Little to no effect of bottom only venting. This is why I say that I see a design flaw there in the MB cap design for the m119. Bottom vent only is ineffective for condensation drainage in a sealed void:
    
    View attachment 82130
    
    Top cut only – visual improvement VS previous 2x:
    
    View attachment 82131
    
    
    Bottom and Top cuts- the least amount of condensation – makes quite a difference inside! Best condition of the lot.
    
    View attachment 82132
    
    As an Architectural Technician by trade I have a good understanding of how to properly ventilate a given space and the m119 distributor cap is no different to those principles. The experiment was for my benefit to see for myself how moisture can condense and get trapped inside my 500E’s cap.
    
    I also have a 300E-24 with distributer cap parked for the identical period of time and conditions as my 500E...... yet it is not stalling, dying out. What gives?
    
    Let’s look and see: (Pics from my own cars)
    
    M119 Cap vents – 2x primary locations at the bottom of the cap when fitted:
    
    View attachment 82133
    
    M104 Cap Vents- many more vents situated all around the cap and more importantly IMO – BOTH top and bottom.
    
    View attachment 82134
    
    IMO this is why my 300E-24 can cope OK but my 500E is impacted by moisture. Therefore I have satisfied myself if nothing else that I should cut more ventilation slots in my 500E's caps, in particular through the top in both caps with a dremel in order to allow moisture trapped in there to escape as the motor warms up.
    
    I will take photos of the slots cutting in a day or two

On my S500 coupes replacement m119 motor I am renewing all seals in the engine. All except the head gaskets that is.

Note that the original seal rings behind the distributor rotor arms feel quite hard. The new seal rings feel nice and supple in comparison and I am glad I am changing them when comparing old and new side by side.

View attachment 86271

Sorry for no cap vent mod updates on my 500E. My S500 coupe will be the participant now since it will hopefully soon be running and used as a weekend driver through winter. That will be perfect for the moisture scenario VS my 500E which is soon to be tucked away for winter and wouldn't give useful data.

I dont understand the need to create a new thread on this topic. It has been covered may times on this forum. Indeed by creating a new thread it brings up the same points as before over and over again.

I would suggest that the mods might create a Distrubuter Cap super thread which combines the 3 or 4 main threads on this very subject.....

 

[JC220]

I have nothing to respond to in post #10

And as stated I myself Identified this cap problem years ago. It is pretty easy to spot to be fair!

I am sharing my own thoughts when I finally got time to mod my caps after talking about doing so since 2019....

As my tests show moisture travels vertical. Hence why I really wanted vents directly at the top!! Anyhow irs all good folks what we can all agree on IS the need for extra custom vents on your m119 caps

Additionally whilst all of this information is on 500E board- it is scattered everywhere and not one thread to clearly address all points. Which this thread does. Given the regular new members having ignition problems this one stop thread gives them the info they need IMO

 

[maw1124]

@JC220 (and @robm.UK), thanks for this. I hadn't thought about this as a recommended upgrade to the stock distributor caps but it makes too much sense. My distributor, seals and insulators were done recently and I doubt this technique was applied. But thanks to you I have it handy for "next time". My car lives in a high humidity, high heat environment (FL) so we'll see how the new-ish distributor progresses.

Cheers,

maw

 

[JC220]

My car lives in a high humidity, high heat environment (FL) so we'll see how the new-ish distributor progresses.

Good stuff, did you have ignition issues prior to replacement? (Presume so)

FWIW I would add the additonal ventilation slots no matter what climate you are in.

After all it costs basically nothing to cut the slots and ensures any moisture is able to ventilate. IMO It is not worth the effort to try and determine which regions may or may not need the slots. Because it is almost impossible to know exactly what conditions, driving habits and seasonal changes a specific car will go through with accuracy.

I downloaded Robs report there. As he rightly stated, my mods are not like his...... because they are not his!! I did not read or refer to his report when doing my mods which I planned for years as evidenced. But I degress on that.

What I suggested here regarding slots I believe to be the best case given there is NO recess left at the top for condensation. But I do not believe slot placement is anything to keep you awake at night. Fact is there were none and now there will be more around the top so any slots is a much needed improvement.

No one will really read and digest a 81 page report on the subject IMO. Neither will I. I don't need to - this is a clear case of poor design and easy little to no cost fix.

What little I did read of it does not align with my experiences and the toughts of this forum for many years. Eg; Page 67 states: "They do not need to be changed UNLESS there is obvious carbon tracking, or the cup has been affected by heat and moisture". This is regarding the Insulator Cups.

Everyone should do themselves a huge favour and renew these insulating cups whilst they are still available new and at reasonable cost from Bosch as they ARE KNOWN failure parts. And these defects are more often than not, not visible at all. If they are circa 30 years old junk em - end of story.

As one last bit of information I DID omit from this thread was the dreaded allen key fitment issues and the possible additional mod to swap the screws out for better fitting items.

This is another documented problem area whereby the bolts strip out. Worth a read before you tackle this job. (Indeed will update post #1 too. EDIT See GSXR post below which advises this affects Bosch rotors!)

Stripped bolt heads on distributor rotors: How to remove?? HELP | M119 Engine

Hi guys, I tried to replace my old rotors and could not do it :hammerhead: It is 3 mm hex but it spins inside of a bolt (either bolt was crap or it was too tight) anyway now tree bolts are completely gone:pissed: , they are round inside instead of angular 3mm hex. :fun: So ... any ideas how...

www.500eboard.co

You want:
· M5 Thread
· 4mm Cap head (Vs old 3mm cap)
· 14mm Thread length. It does NOT matter at all if the new bolt is fully threaded vs the old part threaded one.

Thread length can be + - 1-2mm. Or order longer ones and cut them down to match the original bolt length.



This provides a 4mm allen slot VS the weird malfitting 3mm items the rotors come with.



I should have done that too but had not time - when doing my S500 soon I will change these bolts too.

 

[gsxr]

That reminds me: The Bosch rotors have bolts which are some weird size hex socket, and no standard metric nor SAE sizes fit snugly - which is why so many people have problems with Bosch rotor bolts, and replacing them is recommended if you use Bosch.

My solution was to switch to OE/Genuine rotors made by Doduco, which have bolts that are a snug fit with any 3mm hex driver. Once I learned this (only a few years ago), I never bought Bosch again.

I don't know if Bremi or Facet rotors have bolt issues or not, I've never bought either brand. I think one of my cars may have Bremi rotors courtesy of a PO, if so, I'll see what those bolt heads are like.

 

[JC220]

That reminds me: The Bosch rotors have bolts which are some weird size hex socket, and no standard metric nor SAE sizes fit snugly - which is why so many people have problems with Bosch rotor bolts, and replacing them is recommended if you use Bosch.

My solution was to switch to OE/Genuine rotors made by Doduco, which have bolts that are a snug fit with any 3mm hex driver. Once I learned this (only a few years ago), I never bought Bosch again.

I don't know if Bremi or Facet rotors have bolt issues or not, I've never bought either brand. I think one of my cars may have Bremi rotors courtesy of a PO, if so, I'll see what those bolt heads are like.

I believe my S500 to be done in the next couple of months has Bremi Caps and Rotors Dave, courtesy of PO also.

You are correct I went for Bosch rotors and caps on my 500E. In future I would try MB dealer as you say.

 

[maw1124]

Good stuff, did you have ignition issues prior to replacement? (Presume so)

FWIW I would add the additonal ventilation slots no matter what climate you are in.

After all it costs basically nothing to cut the slots and ensures any moisture is able to ventilate. IMO It is not worth the effort to try and determine which regions may or may not need the slots. Because it is almost impossible to know exactly what conditions, driving habits and seasonal changes a specific car will go through with accuracy.

I don't recall any, actually, certainly nothing like you describe @JC220. I think my mechanic noted a hiccup and traced it back to the caps and rotors. I was away and authorized the work and didn't think much about it. I agree that trying to trace it back to climate, driving style, frequency and whatever else might go into such an algorithm probably doesn't make much sense. I find it more curious that some caps were slotted and others not from the factory.

Cheers,

maw

 

[JC220]

I find it more curious that some caps were slotted and others not from the factory.

Exactly yes. Whilst all caps of the era (m103, m104, m102 etc) had correct ventilation slots for some reason the m119 missed out.

What is less clear overall is:

Did this issue affect the cars when young and to what degree if any(?) Ie, what factor makes the frequency of problems so prevalent now? (Probably the aging of overlooked components such as the insulators and camshaft radial seals is a contributing factor)

Why after so many years has the cap design remained the same, without slots? Surely at some point an MB technician spotted the issue and could have reported it back to MB HQ?

Those questions will probably never have a concise answer but the ignition recommendations suggested here and elsewhere throughout this forum make for the best solutions.

 

[gsxr]

I vaguely recall asking Klink about this, and it's possible that back in the 1990's, a lot of caps & rotors were replaced under warranty. And by the time the engines were out of warranty, MB had little interest in "fixing" the problem by redesigning the components, since they had already moved on to coil-on-plug distributorless ignition on the V8/V12 as of 1996 USA model years (mid-1995 calendar year).

 

[JC220]

I vaguely recall asking Klink about this, and it's possible that back in the 1990's, a lot of caps & rotors were replaced under warranty. And by the time the engines were out of warranty, MB had little interest in "fixing" the problem by redesigning the components, since they had already moved on to coil-on-plug distributorless ignition on the V8/V12 as of 1996 USA model years (mid-1995 calendar year).

Yes that makes sense! The m104 etc with coil packs is infallible in comparison, I wish I had an m119 with coil packs!

It was really disappointing when my 500E stopped on me a couple years back because of this issue despite rigorous maintenance and new caps / rotors.

What happened was the typical extended cranking and misfiring when I started it up after it sat outside for a few weeks. I hoped it might clear up with a drive, sometimes it did and up until then she never actually died.

Went to a filling station first a few miles down the road. Got fuel, set off again and noticed misfiring alot worse and then it died out at 40mph approx on a road. There was a hard shoulder so I coasted it in. Refused to re start. Cranked over and stank of fuel.

Got my GF to come collect me whilst my bother stayed with my 500E. Grabbed a small can of WD40 and 5mm allen wrench in my garage. Removed the caps, wiped out the moisture and lashed it all with WD40. Away it went again full power no issues.

Since that event I do actually carry a small can of WD40 and a 5mm Allen wrench in the boot of my 500E. Now I finally did the mod and will be driving it again soon I hope the system will be reliable.

 

[gsxr]

I had similar experiences in the past on a couple of cars, and it took me a looooong time to figure out the root cause... there are old posts from years ago documenting my headaches. All new components would fix the problem but I wanted to find a solution that didn't cost $400+. I think adding the additional ventilation slots may be the long-term cure. I need to do this on multiple cars!

 

[maw1124]

Certainly with the heat in the engine bay for which these cars are particularly notorious, more ventilation everywhere seems like a good idea... especially if (as is the case here) condensation build up is suspected... make that heat your friend.

maw

 

[robm.UK]

Sorry @robm.UK, this is my own thoughts on the subject! I am not using your report

Nope to that bud. Sorry but that dog don’t hunt.

Do you recall copying my 2017 posts from Benzworld in May 2019? Yes... you did! I didn’t know you did that at the time. It’s in one of the posts you put up earlier. A credit or short note would have been appropriate, since you are also a member of BW too.

Anyhoo, these (my) posts explained the condensation problem and the vent solution in detail. They formed the basis of my 2018 report that you profess to know nothing of the detail.

But of course, while you copied these posts and disseminated them, you did not look at them, use them or let them inform your decision making, right?

.... it is a problem I myself recognised about 5 years ago when I first looked at an m119 distributer cap.....

Nope to that too bud. Off and away in your own world, right?

Note that I posted many thoughts and carried out my own testing on the need for m119 cap mods WELL before your report ever existed. Indeed on this very forum....

Of course, because you wrote this, you must believe it to be true.

Except that you haven’t provided any relevant posts prior to May 2019 that predate my report, and I cannot find any for that matter.

The 2018-06-15 version of the report, which is similar to the current 2020 version with the exception of the personal details on the front cover and the removal of a blank page, was issued to Bosch Global Research and Development on the 13 November 2018. This was the report that @Duh_Vinci obtained from Benzworld and posted extracts on 500eboard on 20 Oct 2020. (No issues with that D).

As I wrote earlier, I posted summary updates and extracts at Benzworld throughout 2017 and onwards.

As to whether you intended to follow my report or not is not a point that I was making in my previous post. You have departed from my recommendations and you have acknowledged that.

What is most important to me is that the correct information is put out so that others are not put to wasted effort or unnecessary expense. This was why I made my comments on your post.

Please, at the very least, correct your post to show an adequate number of vents, and vents that are deep enough to be effective, and credit others where you use their work.

In your line of work you should understand a risk based approach. It should therefore not be too onerous for you to grasp that M119 motors that reside in the south and south eastern States of the US are not going to be susceptible to this problem. For the love of God don’t modify your distributor caps if you live in a dry, desert environment like Nevada. The consequences of ingress of dust will outweigh any benefits that you will see from the modification.

Regards
Rob

 

[maw1124]

^^^ Dude, really?! Let it go already. It's a simple idea. A good one, sure, but a simple one nonetheless. Not copyrightable. Not patentable. If it was, MB would own both the copyright AND the patent. Anyone "could" notice that some distributors were vented from the factory and some not, then deduce a "solution" here -- it's really just an idea, as NONE of this is proven (despite the existence of an 81 page paper on the topic). That paper, while helpful, doesn't "occupy the field" in USPTO terms. So who is so needy that they need to claim exclusive credit? Let's just move it along. This isn't BanzWorld because no one wants this type of BS here.

maw

PS... USPTO = United States Patent and Trademark Office (for the uninitiated claiming patent status to the idea).

 

[Jlaa]

Hello @robm.UK - thank you for your well researched report and presenting your findings here. Your posts have certainly added to the tribal knowledge here! Indeed, I am grateful for your willingness to share!

As well, @JC220 - as always, thank you so much for showing all of us neanderthals what you do! I remember some years back you talking about cutting vent holes in the caps!! I have been following these ignition problem threads here since the day I bought my car some 5 years ago. I have learned so much from you ---- 4mm allens for the Beru caps, that I never want to own a twin turbo v12 Benz, that the project farm guy is secretly your lover, excuse me, man crush, etc. etc etc....

Anyways --- I DGAF whose schwing is bigger, or who came up with what first ---- as far as I can tell we all owe people like @gsxr and @gerryvz and @Klink and @jhodg5ck and everyone else I see around here like @emerydc8 and @sheward and @Trae and @5thscaleracer and @LWB250 and @northNH and @2phast and @speedy300dturbo and and and and and ..... a big big big big big big big big favor because everyone is so willing to share and be selfless and humble about it.

Thanks everyone. I like coming here because most everyone here has no need to hold an ego. Thanks, gang, for making this a great place.

 

[JC220]

^^^ Dude, really?! Let it go already. It's a simple idea. A good one, sure, but a simple one nonetheless. Not copyrightable. Not patentable. If it was, MB would own both the copyright AND the patent. Anyone "could" notice that some distributors were vented from the factory and some not, then deduce a "solution" here -- it's really just an idea, as NONE of this is proven (despite the existence of an 81 page paper on the topic). That paper, while helpful, doesn't "occupy the field" in USPTO terms. So who is so needy that they need to claim exclusive credit? Let's just move it along. This isn't BanzWorld because no one wants this type of BS here.

maw

PS... USPTO = United States Patent and Trademark Office (for the uninitiated claiming patent status to the idea).

Exactly this! My posts are staying as I see them and it's not crucial or to be over thought.

Nor did I steal someone else's work or owe them credit either. (I bought my 500E in 2015 which was my first m119. I immediately started working on my 500E per my owners thread. After having many ignition issues with my 300E-24 I could see the lack of vents in the m119)

Notwithstanding this - I'm quite sure we are not the first people to spot the lack of vents.

Nor is it anyone's exclusive idea or right!

 

[JC220]

Except that you haven’t provided any relevant posts prior to May 2019 that predate my report, and I cannot find any for that matter.

You have a short memory @robm.UK

Recall posts below no? I just noted them again there now

M119 Ignition issues when warm | M119 Engine

Hello all, New member of eboard and new Owner of a 95 SL500 (35K miles only) with M119 engine. A little bit of background: Recently took over a car from my father. He bought it new in 95 and drove it for about 17 years. Then, it was unfortunately left (read: neglected) in the garage since...

www.500eboard.co

I did want to flag the fact that one of our long-time members, @500AMM of Norge, came up with this solution more than 5 years ago and it seemingly worked at that time. So I view the curent dialog and findings from @robm.UK as further confirmation of what had already been posited.

Stripped bolt heads on distributor rotors: How to remove?? HELP | M119 Engine

Hi guys, I tried to replace my old rotors and could not do it :hammerhead: It is 3 mm hex but it spins inside of a bolt (either bolt was crap or it was too tight) anyway now tree bolts are completely gone:pissed: , they are round inside instead of angular 3mm hex. :fun: So ... any ideas how...

www.500eboard.co

Lets move on shall we please @robm.UK ? Sorry to anyone reading this but some points have to be corrected this is why 500E board differs from BW. This information is not exclusively patented by Rob.

Those Norge guys are clever.

Thanks for sharing that. I had not seen that before.
I’ve got a heap of links to threads from all over going back before 2009. All variations on the same theme..

I ain’t claiming to be Neil Armstrong

 

[ChrisH]

I have been having issues with replacing caps and rotors most recently caps rotors plugs and wires and still it failed with this accumulated gunk inside the caps so I modified the caps with the additional ventilation slots , and in about 300 miles later it recurred. I had not Replace the insulator cups and I am doing that now hopefully this will resolve the issue I’m including a few photos below all done after the cap modifications

 

[ChrisH]

(

I have been having issues with replacing caps and rotors most recently caps rotors plugs and wires and still it failed with this accumulated gunk inside the caps so I modified the caps with the additional ventilation slots , and in about 300 miles later it recurred. I had not Replace the insulator cups and I am doing that now hopefully this will resolve the issue I’m including a few photos below all done after the cap modifications

 

[ChrisH]

Sorry for the duplicate photos, but of particular interest to me was the accumulation of the “ mystery gunk” on the flanges of the distributor cap outside of the immediate enclosed environs?

 

[gsxr]

Sorry for the duplicate photos, but of particular interest to me was the accumulation of the “ mystery gunk” on the flanges of the distributor cap outside of the immediate enclosed environs?

The gunk appears to be across the bottom edge of the cap, where an engine oil leak would cause oil to accumulate, and attract debris. The source of the leak is typically the cam advance solenoid, but could be elsewhere nearby if "north" of that edge. Ideally you want to clean all oil residue and locate the leak source. Stuff clean paper towels around to help pinpoint where it's coming from.

I'm assuming the cam radial seal, behind the insulator, was OK / not leaking. Doesn't hurt to replace these proactively though, they are inexpensive.

 

[JC220]

I have been having issues with replacing caps and rotors most recently caps rotors plugs and wires and still it failed with this accumulated gunk inside the caps so I modified the caps with the additional ventilation slots , and in about 300 miles later it recurred. I had not Replace the insulator cups and I am doing that now hopefully this will resolve the issue I’m including a few photos below all done after the cap modifications

Take a look over posts numbers 1 & 2 in this thread. I would advise to follow all steps. For example replacement of the insulator cups and cam seals may be what is causing the residual issues on your car despite having additional vent slots added.

My 500E still lives outside in very humid damp conditions here and hasn't been driven much. Despite this the ignition issues never reoccurred after these mods being carried out. It is 100% success thus far. Haven't got to my S500s m119 yet but will carry out same mods before it is taken out of hibernation this spring.

 

[ChrisH]

Take a look over posts numbers 1 & 2 in this thread. I would advise to follow all steps. For example replacement of the insulator cups and cam seals may be what is causing the residual issues on your car despite having additional vent slots added.

My 500E still lives outside in very humid damp conditions here and hasn't been driven much. Despite this the ignition issues never reoccurred after these mods being carried out. It is 100% success thus far. Haven't got to my S500s m119 yet but will carry out same mods before it is taken out of hibernation this spring.

Thanks guys for the advice, replacing cam seals next week ( Seal Team Seven )

 

[mwaldron]

I am embarking on this mod this weekend, and have been plagued with this issue for years. I am contemplating modifying my current caps <5K miles and trying a hydrophobic coating on the insides of the caps (I have an extra set of NIB caps in reserve) while protecting the electrical posts. We have severe temperature swings during seasonal changes and I have been stranded so much that I need to regain drive-ability confidence. The car has been parked for two years now, is there anything special I need to do? I grenaded a M117 by not priming the chain tensioner prior to sitting up for a while. I have cranked it with coil wires out with the intent of circulating oil prior to firing it up.

 

[gsxr]

Don't worry about starting it after years in storage. I've done this multiple times. To crank without firing, disconnect the crank position sensor at the EZL, much easier than disconnecting coil wires. A code will be stored, clear this later. If possible, drive the car 20+ minutes (don't just let it idle) so the engine oil and ATF get up to operating temp.

 

[mwaldron]

Thank you Dave!

Mark

 

[smalldosedaily]

Hi all,

I have been meaning to address this on my little used 500E for years.... it is a problem I myself recognised about 5 years ago when I first looked at an m119 distributer cap..... Compare to any other distributor cap of the era such as an m104 and you will see there are NO ventilation slots at the top or top sides of the m119 caps. That and some other parts now aged / defective add to your woes!

This thread is not intended to be all encompassing. It is not getting bogged down into the ifs or whys. It is simply a straight forward and to the point thread to show what every m119 engine with distributor caps needs done to it now in order to provide reliable service. My own 500E farts, coughs, had extended cranking at times and has died on the road before due to this m119 problem.

Here is what her caps looked like when removed:

View attachment 135167

The A typical m119 cap contamination. Here is what I did today:

First make a reference mark on the top point of your caps. (I know my caps are recent new less than 1k miles in my ownership so I am re-using them)

View attachment 135168

Check if your ignition cables are fitted with number labels. Mine were not so I used a paint marker. This is concealed anyway by the engine covers and makes it very clear. Note that the caps are marked L# + R#. So you look at the cap and mark the cable based on which side of the motor the cap is fitted as viewed from the drivers seat.

View attachment 135178

Remove the caps, rotors and rotor arm brackets.

View attachment 135169

Now remove the old cam seals. Since my 500E has recent new cam cover gaskets etc I chose to replace these in situ. (You could also pull the cam covers, power steering reservoir and front head covers if any if those are leaking)

To remove the old seals, punch one side inwards slightly then use a hook implement in order to pull out the seal.

View attachment 135170

View attachment 135171

I cleaned up the rust from the cam shaft with fine sandpaper, wd40 and scotchbrite. Fiddly but important.

View attachment 135172

View attachment 135173

Next get your new seals ready. Lube the inside rubber with grease and be very careful that you start the lip on square and gently or the spring can pop off the back of the radial seal! I also use a non setting loctite brand gasket dressing on these radial seals and a large washer then socket to press home. You would want about 6 inches of m6 stud to do this more easily.

View attachment 135174
View attachment 135175
View attachment 135176
View attachment 135177

Clean all areas with brake cleaner and Next part is mods and re-assembly

EDIT- Before you start please do read the thread below:

This is another documented problem area whereby the bolts strip out. See post #15 below also!

Stripped bolt heads on distributor rotors: How to remove?? HELP | M119 Engine

Hi guys, I tried to replace my old rotors and could not do it :hammerhead: It is 3 mm hex but it spins inside of a bolt (either bolt was crap or it was too tight) anyway now tree bolts are completely gone:pissed: , they are round inside instead of angular 3mm hex. :fun: So ... any ideas how...

www.500eboard.co

what are part numbers or where do i get the gaskets? i have everything else to replace in that system, doing the job in a week or so

 

[JC220]

what are part numbers or where do i get the gaskets? i have everything else to replace in that system, doing the job in a week or so

The Cam seal part number is A0189977947 - order them from any MB dealer they will likely take a number of days to come into stock so best order now. You require 2no. Would advise on buying 3 just incase one gets crooked and damaged during install and if you depend on the car for transport. I bought Elring versions from ebay per my photo in post #1

 

[JC220]

My 500E has been sitting outside in my carport all winter. I started it a couple of days ago, put fresh fuel in it and took it for a good drive.

I also took it to work today and went for a long drive after work so put 120 odd miles in it in one day.

My 500E has been sitting for months and exposed to extreme humidity in Ireland and has performed 100% flawlessly. No misfires, no stumbling not a thing. Whereas before it was almost certain to cut out and die on me on the first outing requiring removal and drying out of distributor areas and the cycle would repeat again days or weeks later.

These modifications definitely do work and will restore smooth running and absolute confidence in your m119 powered beast

A footnote here is if you have experienced any m119 cutting out or misfiring don't cherry pick one or two elements to do here. Do them all without question and be done with it.

 

[gerryvz]

Bonus is that the mods are also fully robm-uk approved, doubling their veracity.

 

[JC220]

Bonus is that the mods are also fully robm-uk approved patented, doubling their veracity.

 

[alpineviking]

You want NEW insulators. Unless you KNOW you already replaced these in the past couple of years go ahead and fit new ones even if the old ones look OK. They are known failure points and the micro cracks may not be visible to your eye.

View attachment 135179

Personally I spray some WD40 on the head area behind where these insulator cups fit. Water Displacement formula 40 is ideal for this use but if you don't want to use it skip this step.

Fit the new insulators in place and install the rotor arm brackets with a tab of blue loctite on the threads.

View attachment 135180

Clean the rotor arm contacts and re-install again with a very small drop of loctite.

View attachment 135181

Now for the caps - pre mods:

View attachment 135182

Remember those reference marks made before disassembly at the top most part of the caps? I cut 3 slots there and 2 more sets additional at 10 and 2 o clock positions. This is a crucial modification in order to allow atmospheric or other moisture to vent and escape from the distributer caps. I also cleaned the terminals gently with electrical cleaner and a fine scotch pad.

View attachment 135183

Demonstration using an old insulator cup to show how these slots will allow moisture to pass the O ring:

View attachment 135184

Refit both caps, make sure all cables are back on the correct spot and tight and put all covers back on.

My 500E cranked right up and is running fantastic today. Time will tell if this will solve her ignition problems but I believe this is as good as it gets and it will now be able to vent the moisture and run properly.

Worth noting also that the m119 runs better with a 1mm spark plug gap VS the factory 0.8mm spec. So if unsure, buy a new set of plugs and make sure they are gapped at 1mm for best running.

That's it, you should have many years reliable service from your distributor cap m119 if you followed each step!

Hello everyone… I would like to make a little addition to this very well thought out tutorial. I am electrician, and we electricians are always instructed to never use WD-40 near electricity. This formula is blended with graphite, and graphite is an excellent conductor. With due respect to the author of this tutorial, I would suggest cleaning the components with plastic safe electrical cleaner or Electrical silicone spray oil. Dry components well, as most cleaners are volatile, and could make a nice explosion inside the distributor cap.

 

[JC220]

Hello everyone… I would like to make a little addition to this very well thought out tutorial. I am electrician, and we electricians are always instructed to never use WD-40 near electricity. This formula is blended with graphite, and graphite is an excellent conductor. With due respect to the author of this tutorial, I would suggest cleaning the components with plastic safe electrical cleaner or Electrical silicone spray oil. Dry components well, as most cleaners are volatile, and could make a nice explosion inside the distributor cap.

Thanks for your feedback, just to note WD40 stands for water displacement formula 40. People have been using it for decades on ignition components in the UK which is actually its main purpose.

In this thread I suggested it could be used on the engine casing behind the ignition components as an optional step. Not within the caps themselves as the aim of this thread is to address the design issue / root cause of the condensation in the first instance.

Anyway, not bothered what people spray on their igntion systems so do as you will.

 

[gsxr]

Quick update on this topic: If you have a Dremel or equivalent rotary tool, the "EZ456" cutting disc works PERFECTLY to add the vent slots in a distributor cap. I slotted 2 new Beru caps on Wednesday, but forgot to take pictures afterwards, ooops. The EZ456 disc is included with some Dremel kits, it came with the one I bought a few years ago. A 5-pack is $13 at Amazon or Zoro.

https://www.amazon.com/Dremel-EZ456-2-Inch-Rotary-Cut-Off/dp/B000FBLRVK

https://www.zoro.com/dremel-e-z-lock-cut-off-wheel-1-12-in-dia-pk5-ez456/i/G0313397/

EDIT: This cutting disc requires the use of the Dremel EZ402 EZ Lock Mandrel. My Dremel kit included this mandrel, check if you have it.

 

[gsxr]

Here's an update on my car that had odd liquid present on the insulators, as described in post #132 of this thread.

The car referenced above was driving normally 99% of the time since the work performed in Sept-2021. This spring when fired up after 7 months of storage, it ran normally for a 25-minute test drive. But when parked for maybe 10 mins, after a restart it began misfiring.

For reference:

• Caps are Beru, 9 years old, but only 5kmi. NO vent slots cut.
• Insulators are Bosch, 9 years old, but only 5kmi. Visually perfect.
• Rotors are OE Doduco, 3 years old, 3kmi. Visually perfect.

I removed both caps for visual inspection. The driver side (left) looked good and was mostly dry. The passenger side (right) had visible moisture in the cap along with visible carbon tracks from arcing / misfiring. Yep, time to add the vent slots. Once again, the insulators had a thin film of liquid (NOT water) covering both front & rear surfaces. The aluminum head cover behind the insulator is bone dry on both driver & passenger sides. Since the cam solenoids were original and not replaced or resealed, there was still the small amount of engine oil present at the lower edge of the caps.

So, I installed re-sealed cam solenoids/magnets per @JC220's writeup (click here). Disassembled, cleaned, de-oiled, and reassembled the magnets with Permatex Ultra Black RTV (the super-oil-resistant stuff). Hopefully this will eliminate the trace of engine oil which keeps reappearing at the lower edge of the distributor cap. The cam magnets were installed with anaerobic sealant per the FSM. The head surfaces surrounding the cam magnets and distributors were carefully degreased to help identify any oil leaks in the future. It's all clean & dry right now.

The passenger cap looked pretty bad, but cleaned up nicely, as did the driver side. I cut the vent slots (as described in post #2 of this thread - scroll up) to improve ventilation and hopefully eliminate the misfiring due to water/condensation buildup 20-30 mins after a cold start. The rotors were fine and reinstalled as-is. The insulators had the film of unknown liquid wiped off with solvent and reinstalled.

I'm hoping this will cure the occasional misfiring permanently, assuming the engine oil leaks are 100% stopped. The added ventilation should prevent water/condensation from building up inside the cap, and the lack of engine oil should prevent the weird film building up on the insulator. I plan to take everything apart next winter while in storage (after a summer of driving/racing) to see if the insulators are still nice & dry, then monitor yearly after that.

I did pretty much the same thing on a different car (cut vent slots in the caps, eliminated oil leaks with new cam magnets, etc etc - photos here) and will monitor that engine as well. This is the first time I've replaced or resealed the cam magnets and I'm really hoping it will be the permanent fix for both cars. I also plan to re-seal more cam magnets and do the same job on other cars, it's just a PITA because the power steering reservoir has to come off to do this job.

Photos below, before & after. Note the engine oil visible at the bottom of the cap (at the vent slots) in the "Before" pictures.

 

[gsxr]

Well I didn't need to wait long for an update! Within about 75 miles of driving, there is already oil residue at both electrical connectors. I had disassembled these, degreased the wires & metal female sockets, and replaced the plastic pin bushing housing (connector). And, the solenoid male connectors were bone dry when installed. I cleaned everything again, this time adding a small paper towel diaper below the connector.

I believe the magnet inside is not as "sealed" as people think it is. Somehow, oil is getting inside that and leaking out the connector. It may require heat from the engine to expand the oil and push it out. After I had re-sealed these, I set them vertically on the workbench, electrical connector downward, for several days before installation. One had a trace of oil dribble out, the other was mostly dry. So, there was definitely some amount of oil inside the electrical windings. But there's no way to open this up to clean it out!

I'm hoping it's a small enough amount of oil inside the windings that eventually it will go away. However, what I don't know is if the oil can still enter the "sealed" winding after we've encased it in RTV. If oil can still get inside, it will still get pushed out from heat / pressure / etc. Grrrr.

 

[smilecenterlab]

i feel better now.

 

[nocfn]

wish I did

 

[nocfn]

wish I did

What I should of said that when I just got tired of the issue Dave has, I just splurged and bought new ones, new bolts and new armatures as the manual said to and there is not any leaking problems since.