HOW-TO: Repairing leaking M119 cam advance solenoids / magnets

[JC220]

Moderator edit: To replace with new solenoids/magnets instead of repairing, order 2 each of the following items:

• 119-051-00-77 magnet/solenoid, $109 MSRP
• 111-051-00-43 new style armature, $10 MSRP
• 104-990-10-04 single-use armature bolt, $3 MSRP

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Preamble

A common problem on many 1990's Mercedes is engine oil weeping out of the edges of the Cam Magnets - necessitating their renewal. This is something my 1992 500E was suffering from in a big way with both magnets leaking oil all over the front of the engine. Fitting new magnets is an option - but I chose to rebuild mine since the new Magnets may also leak again eventually.

This is my method to re-seal the Magnets for what is a more permanent fix. It involves dissembling the magnets and using a quality high temp RTV sealant to bond the original gaskets in place creating a permanent Oil tight seal.

It appears the OE seals shrink somewhat over time and exposure to Oil / heat. Thus the Oil makes it’s way out from the edges of the Magnet casing. I prefer to retain the factory seals inside and use the RTV to bond & 100% reseal them in place. 4 very small gaps require sealing with this method - hence why 4 beads of sealant are needed. You could also totally replace the seals with new suitable thickness neoprene gasket material cut to the correct shape - or remove the seals altogether if you have a suitable gap filling high temp sealant / glue - but the chance of success is much higher when you only need to seal 4 tiny gaps (>.01mm) rather than 2 large gaps (>2.5mm).

This is what you find when you first open a magnet – saturated with Oil inside.




The magnet itself is a solid cast sealed plastic unit & takes no harm from the exposure to Oil. Therefore the only issue is the Oil seepage - which is why repairing a Magnet like this is a good option and it will likely outlive it's new replacement!

The removal / refitting of the magnets has been discussed here before - see Gerry's DIY here. (Post #49)

I will try to keep this DIY clear and concise - thus I will detail the re-seal of the magnet only for clarity.


You will need:

• 12no 3.2mm diameter x 10mm closed end countersunk pop rivets + riveter
• 1 tube of High quality, high temp RTV sealant
• A 3.2mm HSS drill bit
• A HSS Countersink drill bit
• A drill press preferred especially for the countersink drilling
• Clean rags & a can of brake cleaner

Step 1 - Use a 3.2mm drill bit to drill out all 6 rivets from behind. There is a concave shape to the rear side of the rivet which self centres the drill bit nicely.




Step 2 - The rear plate will now come off the magnet. Remove the magnet from within and the 2 seals. Clean everything up with a clean rag and brake cleaner. All traces of oil must be removed.




Step 3 - Use a countersink drill bit in the rear plate face to allow the rivets to sit flush. (Rivet must be flush or slightly lower than the face of the plate)




Step 4 - Give all parts a final thorough de-grease / clean. Lay 4 neat beads of RTV sealant, re-assembling the magnet in stages as shown in the photos. (I missed one step above the magnet itself but there are 4 beads of sealant in there)





Step 5 - Place all Rivets into their seats to align the rear plate accurately & clamp rear plate tight. Now pop all rivets into place.





Step 6 - Wipe away excess sealant from inside the magnet body - I used a screwdriver wrapped with a clean rag to get right into the centre gap where the cam solenoid goes in.





Allow a minimum of 48 hours for the RTV to set up before re-installing the magnets. Enjoy!


NOTE:
Do not be tempted to use RTV to fit the magnets back onto the Engine. The correct anaerobic MB sealant should be used as per Gerry's DIY (Or Loctite 574).

.

 

[samiam44]

Re: How to - Repair leaking cam magnets

FYI,

I did a permanent fix using bucked rivets and military sealant... you can find it out there. RTV doesn't have much bond strength... If your using aluminum pop rivets, there will be galvanic corrosion issues.
Mine are still dry...


M

 

[JC220]

Re: How to - Repair leaking cam magnets

Yes I had seen your thread also samiam44 but had no clue where to source that adhesive. But really the RTV will not fail - it's in there good & only has to seal very small gaps. I generally try not to use RTV just because it sticks and glues stuff together but it is perfect for these magnets.

The original rivets in my magnets were Aluminium- maybe some magnets are different but I can't imagine the aluminium pop rivets giving much trouble

Bucking rivets is not something I wanted to learn on these magnets! The countersunk rivets are ideal really. I did both of these magnets in less than 90 minutes. Now I have it figured out I am going to rebuild the cam magnets on both of my other m104 w124's also.

 

[samiam44]

Re: How to - Repair leaking cam magnets

I get expired adhesive... those FAA rules limit it's shelf life to 1 year. Looks like vans aircraft supply is the cheapest supplier for a pint.
You can use a hammer/punch and a vice as an anvil with A rivets(soft) which is probably the factory rivet. Agreeded, blind rivets are easier..



Michael

 

[Stevester 500E]

Re: How to - Repair leaking cam magnets

Has anyone tried welding the caps together?
Or adding 3 more rivets?

 

[gsxr]

Re: How to - Repair leaking cam magnets

More rivets won't help because the root cause is the internals seals shrinking and no longer sealing.

Welding, if you ground down the edges so it would still fit, would not fix the leak at the electrical connector.

Either way you still need additional sealant involved.

 

[Stevester 500E]

Re: How to - Repair leaking cam magnets

what needs to be done is:
Make a circular groove on both caps, as close as possible to the magnet, and install a rubber o-ring, and put it back together.

 

[JC220]

Re: How to - Repair leaking cam magnets

I would not try welding the magnets – the heat would damage them and distort the sealing face giving you bigger problems. Dave is correct – that electrical connector will leak out oil also – this is where some of the Oil was leaking out on my magnets.



This is a pic from just before I wiped off the excess RTV – you can see how it has filled every last mm of that magnet inside – it squeezes out all around the magnet.




This is a pic this morning of how the RTV has also squeezed out and sealed all 4 the edges of the electrical connector also.




O rings could also fail (harden / flatten) just like the original seals did and besides - won't that cost almost the same as a new magnet to have a machine shop mill a groove in them? For less than £3 of materials expended on both Magnets it ain’t a half bad repair. Trust me – Oil has nowhere to go in the magnet now at all – this is a permanent fix.

 

[doolar]

Re: HOW-TO: Repairing leaking cam magnets

This is pure love this is! I just removed one of my magnets and on closer inspection I can see that they are probably leaking thru the connector. With my discount they're €190 a piece, so happy days that we of course have a member who found a solution!

Thanks buddy, now I'll reseal mine with the help of your How-To tomorrow.

 

[gsxr]

Re: HOW-TO: Repairing leaking cam magnets

Thomas, just FYI... a lower-cost option is to convert to the late-style solenoid + armature, which is much less expensive to buy new.

However, if you have the time to disassemble and re-seal as shown in this thread, that would be the least expensive! (But much more time consuming.)

 

[JC220]

Re: HOW-TO: Repairing leaking cam magnets

The reason why I did this is longevity of the repair. New magnets may well leak again in 5 - 10 years. No biggie but a PITA all the same. This re-seal will last the life of the car. Mine are flawless since - bone dry.

 

[doolar]

Re: HOW-TO: Repairing leaking cam magnets

Thomas, just FYI... a lower-cost option is to convert to the late-style solenoid + armature, which is much less expensive to buy new.

However, if you have the time to disassemble and re-seal as shown in this thread, that would be the least expensive! (But much more time consuming.)

Thanks for the info, didn't know about that, found the thread after a search.

But I'll do the repair, I have all things needed at work so it should be a fun job!

 

[samiam44]

Update, mine are still dry.

 

[JC220]

Update, mine are still dry.

As are the ones on my 500E! Still bone dry. I do have multiple M104 cars to start cleaning up and re-doing now too as pretty much all of the original cam magnets appear to be weeping oil

 

[dorifuto.boi]

Should I try to use a center punch to punch out the mandrel or should I just grind down the mandrel ? I don't know why but the mandrel didn't snap flush to the top of my rivets.

 

[JC220]

Should I try to use a center punch to punch out the mandrel or should I just grind down the mandrel ? I don't know why but the mandrel didn't snap flush to the top of my rivets.

I see what you mean - likely the rivets are poor quality to snap off like that. I would grind them down (carefully!) at this stage. I don't think a centre punch will help much and may undo the rivet clamp strength.

Also the mating faces should be cleaned up right back to metal before re-installing with the correct anaerobic sealant.

 

[darek_u]

I'm just about to reassemble my leaky magnets as per this great how-to but I cannot find anywhere the closed end rivets. Is it going to change anything if I use open end rivets? I presume 10mm length is still the best fit.

 

[samiam44]

What's an open ended rivet?

Pull or blind rivets -cherry max
SolI'd or bucked rivets

Sealant. Google for the mil-pfr-8802. Vans aircraft supply. Proseal

 

[samiam44]

If you use aluminum rivets, there can be galvanic problems. Unless they have a conversion coating.

 

[samiam44]

I used the std 0.094 in drill bit, start and you can pull the hole. If you are close, it should center. Once the head is drilled off, the stem can be removed with a punch.

 

[darek_u]

I meant blind rivets... Apologies for my poor language skills... I was planning on using SS blind rivets. I have everything apart and sent for zinc coating already.

 

[JC220]

This DIY reminds me I never did get to doing my other cars with these magnets! Definitely required on at least 5x of my cars at present so I'll order up a bag if rivets and get to work soon

 

[JC220]

My 500E"s rebuilt magnets are still 100% leak free. 4x more done today, about 6 more still to go

 

[gsxr]

You'll be offering a rebuild service now that you have the procedure down pat!

 

[Berglund]

Hi,
I just have the valve cover installed with new gasket, and now I did take the distributor away on both side. Even the plastic cover behind. It will be dry and clean just around the rotors and brackets.
But some dirt around the cam-magnet cup.
The right side I just removed, time to get this sealed, like the discussion in this thread.
I think I most removed the servo steering oil-cup on the left side, to get the magnet away.
Do you think it will be some leak around her?
Look at the pictures below.
Probably good to have new seals, pack-boxes on the cam-axel when doing this work!
Or is hard to shift this?

 

[hnyc]

I wanted to add my two cents to this as it might give an added insight as to why these things are leaking.
It’s a pretty good system.
Two thin rubber seals sandwiched in between the magnet and the housing prevent the oil from leaving the area.


I used to think that it was oil seeping from the connecting pins but that’s not the case. It’s a solid piece/mold. So how/where is the oil coming from? The rubber seals are still pliant and effective.



Well there’s one area of the seals which isn’t as uniform as the rest.


This is a ‘burn’ mark on one of the rings. This is right where the magnet’s connector is right at the housing opening.

My assumption is that the engine bay temperature is hotter than the engine temperature and the differential is causing the seal to warp. Mind you it’s still soft and pliable at the opening where it’s ‘burnt’ but it obviously doesn’t seal the same. You could blame this on the engine being stuffed in a tight space there with the heat being in abundance, but all M119s leak (in the other body styles) as well as the M104 and M120.
So it’s just a ‘thing’. I don’t know if different seals would help but I’m not sticking around that long. I black RTV’d the thing and put it back in. If it leaks again I’ll have to buy new ones as nothing is coming loose from that cement trap ever again.

Joe thanks for showing this procedure as I would’ve replaced these as I’ve done in the past rather than rebuilding and saving my money...

To be spent somewhere else in this car!

 

[darek_u]

I must say that I failed here... This DIY is fantastic and straight forward. I resealed my cam solenoids a year ago. Left one started to leak slightly through the connector 6 months later. I took it apart again and this time loaded with a lot of RTV. I mean a LOT OF. There was plenty of excess coming out all around the solenoid, including the connector. 6 months later it is leaking through the connector again... Just slightly but enough to remind me that I failed again... In the mean time the right solenoid started to leak through the connector too. I give up this time. I used quality silicone (Dirko), cleaned everything meticulously, including bath in ultrasonic cleaner, put everything together carefully. I also inspected parts for possible cracks - none was found. Maybe I've missed something, I don't know. Anyway, I think I'll go for new solenoids. Do you guys know if aftermarket version is available? I think I saw FEBI one for 6 cyl engine, I believe they are identical?

 

[darek_u]

I did a little research. I can buy Pierburg replacement for reasonable money. Pierburg is OE manufacturer for many valves and solenoids for different German automotive makers. What is the common opinion on this manufacturer?

 

[gerryvz]

Pierburg is fine to use. They also make fuel pumps for MB. Good quality stuff.

If I were you, I'd just get a pair of the MB cam solenoids and be done with it. DO NOTE, that a revised cam solenoid (with the 119 part number) is the only one that is available from MB. The stock one that would have come on the E500E as original equipment had a 104 part number.

If you get the revised design with the M119 part number, you MUST also buy a new pair of armatures that are specifically designed to work with the revised solenoid design. Your original armatures WILL NOT WORK with the revised cam solenoid design. This is all in the factory service manual, I believe. I also mentioned it (and showed photographically) in my recent Top-End HOW-TO article.

 

[darek_u]

Gerry I found and read your post #321 but you don't mention anything about different bolts etc? Unless I missed something?

 

[gerryvz]

The three bolts that hold each solenoid onto the front cylinder head cover are the same as the original ones. You can re-use the original bolts (I'd clean them up because they are going to have dried-up orange koala-claw goo on them, most likely.

You can re-use the two small screws that hold the armatures onto the ends of the cams, though IIRC MB says to replace them. They are easily avaialble and inexpensive (and I think I paid about $7-8 each for the armatures, as well).

 

[nocfn]

FSM clearly states one use bolts for armature. I would hate to find out they were right.

 

[darek_u]

OK, I got it now. I need 111 051 00 43 and probably a new bolt.

FSM clearly states one use bolts for armature. I would hate to find out they were right.

I always wonder why FSM calls for new hardware... I fully understand that some bolts are intended for single use only - these are the bolts that stretch and deform but the one in question - why would they ask for new one? With 7Nm torque stretch is not a problem for sure. Loctite? Not a problem - one can apply a dab of blue, green or red, depending on location and purpose. This is something special with Mercedes, Porsche for example calls for new bolts and nuts on a very few occasions and these are straight forward and self explanatory. Just wondering

 

[doolar]

A slight update - it's now several years since I did the re-seal. My engine bay is still 100% dry, and one of the reasons for that is the re-seal of the magnets.

 

[Matin]

How long does the cam shaft magnets last for before they start leaking again? I suspect one of mine is leaking because the left distributor cap has oil residue at the bottom (see attached).

I changed them approx 3-4 years ago but seems like this may be the likely suspect. I’m not sure where else it would be leaking from that would add this residue into the cap.

 

[gsxr]

That type of leakage is often from the cam magnets/solenoids, or the sealant between the solenoid/magnet and the face of the head. However, since yours are new, the magnet itself should NOT be leaking. Do you know what sealant was used?

You'll have to remove the plastic frame surrounding the magnet and verify the exact source of the oil leak.

 

[Matin]

That type of leakage is often from the cam magnets/solenoids, or the sealant between the solenoid/magnet and the face of the head. However, since yours are new, the magnet itself should NOT be leaking. Do you know what sealant was used?

I used the orange stuff. I think the part number was 001989892010

 

[Matin]

You'll have to remove the plastic frame surrounding the magnet and verify the exact source of the oil leak.

I took the plastic cover off today, looks like the oil leak is coming from the magnet...or above the magnet?

See pics.

What are your thoughts?

Before I go crazy and start ripping everything off, would love to get yours (or anyones) opinion on where you think the leak is coming from.

 

[gsxr]

I took the plastic cover off today, looks like the oil leak is coming from the magnet...or above the magnet?

See pics. What are your thoughts?

It's hard to tell for certain, but it kinda looks like there is a leak from higher up. Are the valve cover gaskets fairly recent, and OE/Genuine? Have you checked the torque on the bolts?

I'd clean everything up and then monitor closely to see if you can pinpoint the source.

 

[Matin]

It's hard to tell for certain, but it kinda looks like there is a leak from higher up. Are the valve cover gaskets fairly recent, and OE/Genuine? Have you checked the torque on the bolts?

I'd clean everything up and then monitor closely to see if you can pinpoint the source.

View attachment 180230

I have no idea when the gasket was changed...last time it was opened was probably ~2 years ago...I'm pretty sure it's OEM but can't say for sure.

I need to change the front timing cover (1190160706) anyway because one of the holes for the distrubutor bolts has stripped and the top bolt does not tighten properly.

I have also purchased a new gasket, so will replace the gasket and magnet eitherway.

Should be good to go after that...

 

[gsxr]

I have also purchased a new gasket, so will replace the gasket and magnet eitherway.

The magnet is recent and very unlikely to be leaking... I'd investigate further before digging in.

 

[gsxr]

I recently re-sealed a pair of original cam magnets via the method @JC220 describes in post #1. 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.

I used stainless steel blind rivets 10mm long (details in this post by @Beater400E). They worked very well to clamp the flange together, but I was not thrilled with how tall the rivets were above the exterior surface of the magnet. One rivet on the driver side interfered with the black plastic surround, I had to cut a notch in the plastic to clear the rivet. With the notch added the plastic surround fit properly. Sadly, I completely forgot to take photos of the too-tall rivets! And, they are covered up by the plastic surround. D'oh!

I'd like to find a shorter blind / closed-end rivet if possible. I'm guessing 7mm might be ideal? Not sure if 5mm is tall enough to function (or if available in that length). I'll have to do some more research. I measured the thickness of the flange, it's approximately 4.9mm / 0.190" thick.

Interestingly, the old cam magnet was last installed in 2014 with OE/Genuine orange anaerobic sealant. The magnet was stuck to the head TIGHT! Prying did nothing but gouge things that shouldn't be gouged. (ooops) I found that a gentle (!) tap with a hammer quickly dislodged it. And, I also discovered that I had probably gotten carried away with applying the orange anaerobic sealant ten years ago. In the attached photo, you can see how much extra orange goo solidified around the center of the hole, and also at the outer edge. There was zero oil leak from the magnet-to-head-cover surface, the oil appeared to be from the seam of the magnet edge, and maybe some from the electrical connector area also.

This time when installing the re-sealed magnet, I applied a ~1/8" bead of anaerobic sealant around the back of the cam solenoid and smeared it with my gloved finger into a thin coating. This method produced much less "squeezeout". I let this dry for several days before starting the engine, to allow some bonus time for curing. 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, but I'll keep an eye on it.

 

[Beater400E]

I used stainless steel blind rivets 10mm long (details in this post by @Beater400E). They worked very well to clamp the flange together, but I was not thrilled with how tall the rivets were above the exterior surface of the magnet. One rivet on the driver side interfered with the black plastic surround, I had to cut a notch in the plastic to clear the rivet.

Yeah, they are a little on the tall side. The eBay seller has 1/4 inch/7mm, and 5/16 inch/8mm as well. Might be worth trying one of those. I'll order up a bag of 1/4 inch/7mm and see how well those work.

 

[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.

 

[RobertK]

f you get the revised design with the M119 part number, you MUST also buy a new pair of armatures that are specifically designed to work with the revised solenoid design. Your original armatures WILL NOT WORK with the revised cam solenoid design. This is all in the factory service manual, I believe. I also mentioned it (and showed photographically) in my recent Top-End HOW-TO article.

I have two questions about this.
The later revised solenoid (A119 instead of A104) in the number) seemed to be better regarding leaking etc. when I read the articles. Is that the right conclusion ?

When I choose for the revised solenoid design (M119 part number) what is the EPC number of the armatures which I need en what do I further need ?

 

[gsxr]

I have a question about this. When I choose for the revised solenoid design (M119 part number) what is the EPC number of the armatures which I need ?

See the blue text at the very top of post #1.

 

[RobertK]

Thanks,
The later revised solenoid (A119 instead of A104) in the number) seemed to be better regarding leaking etc. when I read the articles. Is that the right conclusion ?

 

[gsxr]

Thanks,
The later revised solenoid (A119 instead of A104) in the number) seemed to be better regarding leaking etc. when I read the articles. Is that the right conclusion ?

It does seem that way. However, it may just be a timing thing (they are a number of years newer). Guess we'll find out!

Last spring I upgraded one car to the new style solenoid, and "repaired" the old solenoids on another car. I'm keeping an eye on both.

 

[RobertK]

Allright, I hope they are not NLA by MB.
Are there things I should take into account when replacing and installing the upgraded armatures ?

 

[RobertK]

I have a question about replacing these radial shift sealing rings:
I am not very familiar with this procedure but is it a simply draw-out and push-in action ? Should I grease (with oil) the edges of the ones before pulling in ?