HOW-TO: M104 / W124 Top-End Rebuild [Cylinder Head / Gasket]

[jftu105]

Thank you for the advice. I talked to Jonathan of Blue Ridge MB. He indicated that he needed to check to see if he has the part. He would call me back to give me an estimate. In the mean time, the nice young man told me that he recently restored a W124 and he owns several himself.

I felt bad if I simply pull the car out and sent it to Blue Ridge without giving this young man a chance first. Yes, I informed him about the front seal, the key, and the need for an impact wrench. I also got a quote for 3 hours labor by a highly rated MB specialty shop in Chapel Hill, NC (A Better Wrench). The part is $1100 new from the dealer. One Florida dealership asks $620. So, it seems that the upper bound is $1500 with the full price new part.

https://parts.mercedesbenznaples.co...MIrfmerICp3AIVDBSBCh3TMQZfEAQYECABEgKwVvD_BwE

I will report back on the progress. Jonathan at Blue Ridge will be a top priority once I get more information of the damage from the young man.

Thanks all.

jftu105

 

[gerryvz]

Looks like the part is available as a reman factory part: https://www.mboemparts.com/search?search_str=1040301403

Note the revised part number (104-030-14-03-81) for the reman version. It's less than half of the discounted part price you quoted.

There are also used ones available: https://www.ebay.com/itm/Mercedes-1...onic-balancer-pulley-M104-93-97-/192494239037

Jono will also look and see if there are other issues that need addressing, based on his extensive experience with the M104.

 

[jftu105]

Bad news. The young man put the car on lift and found out that the center bolt was only finger tight. The harmonic balancer is actually fine, but the key was chewed up along with the crankshaft. The engine is beyond repair (cost prohibitive to put in a new crankshaft). I agree to sell the car to him as a scrap and I get to remove as many parts as I can, plus all four tires (new) and the special edition wheel. I will get the throttle body, ECM, harness, radiator (new Nissens), water pump (new), perhaps engine head, alternator, air pump, stainless steel brake hoses, etc.

I feel sad and wonder how could this happen. Perhaps, the key broken and then everything came loose. How could the center bolt come loose?

jftu105

 

[gerryvz]

Somehow it may not have been properly torqued.

Used M104 engines are cheap and easily available; I'd keep the car and replace the engine with a used one, and keep it on the road. If the car is otherwise in good shape, just drop a used engine in, and sell some of the good parts off the old motor to help defray the cost.

Again, something that Jono could easily source and do for you.

 

[JC220]

Bad news. The young man put the car on lift and found out that the center bolt was only finger tight. The harmonic balancer is actually fine, but the key was chewed up along with the crankshaft. The engine is beyond repair (cost prohibitive to put in a new crankshaft). I agree to sell the car to him as a scrap and I get to remove as many parts as I can, plus all four tires (new) and the special edition wheel. I will get the throttle body, ECM, harness, radiator (new Nissens), water pump (new), perhaps engine head, alternator, air pump, stainless steel brake hoses, etc.

I feel sad and wonder how could this happen. Perhaps, the key broken and then everything came loose. How could the center bolt come loose?

jftu105

Wow – sorry to hear that. I presume this was not the E320 you just did the HG replacement on? However, before jumping to scrapping it read below:

This happened to me many moons ago on my 1990 300E-24. The car did the same thing – ate the crank pulley due to what I think was insufficient tightening of the crank bolt. The woodruff key had been mashed / mangled and was stuck into the (slightly softer) pulley material. Result was some scoring on the crankshaft nose, widening of the woodruff slot in the crank and a junk crank pulley which could no longer transmit drive to the auxiliary belt due to no woodruff key. Not good!!!

What I did next was take the pulley and oil seal out to fully assess the damage, and spoke to my local machine shop too. They said “No problem” and explained what to do. The crank nose scoring was so minimal it made no discernible difference to fitment at all. I took some Chemical Metal (Or other malleable epoxy it shouldn’t matter) and pushed it into the now damaged slot in the crank nose. The purpose of this was to create an exact mould of the slot now wore into the crank. The epoxy set up overnight and I delivered the resulting mould and a good used m104 crank pulley to the machine shop.

They then made a custom woodruff key for me which was a PERFECT fit into both the crank nose and for the pulley to slot on. I fitted that custom key, new oil seal and made sure to use a large torque wrench capable of 400nm (Or whatever the spec was) and get the new crank bolt to the proper tightness.

The car has been A1 ever since and never had an issue with that repair.

 

[gerryvz]

You're in North Carolina....Trae's in North Carolina....sounds like a good opportunity for Trae to get his hands dirty working on an M104 swap, seeing as he has good experience with them now

 

[jftu105]

I am in North Carolina but the car is in Atlanta. Yes, Jonathan of Blue Ridge is looking into engine replacement. JC220's solution is worthing exploring. I am driving to Atlanta tomorrow to access the damages and how to proceed from there. This is a blue E320 I bought for $4000 when it was 97,000 miles in 2012.

Yes, it is in top condition and everything works except this center bolt issue, a very rare case. Not the one I just did the HG. Glad that I did the HG so I have an extra to cover the need.

I guess some lock-tight does not help. If this is so critical, MB designer should put a key to the center bolt to keep it from loosening.

If I end up giving up the car, I already made a list to recover as many parts as possible. I just put in some Lemforder tierods and center link, water pump, belt tensioner, etc.

Again, thanks for all the help and suggestions.

jftu105

 

[JC220]

I am in North Carolina but the car is in Atlanta. Yes, Jonathan of Blue Ridge is looking into engine replacement. JC220's solution is worthing exploring. I am driving to Atlanta tomorrow to access the damages and how to proceed from there. This is a blue E320 I bought for $4000 when it was 97,000 miles in 2012.

Yes, it is in top condition and everything works except this center bolt issue, a very rare case. Not the one I just did the HG. Glad that I did the HG so I have an extra to cover the need.

I guess some lock-tight does not help. If this is so critical, MB designer should put a key to the center bolt to keep it from loosening.

If I end up giving up the car, I already made a list to recover as many parts as possible. I just put in some Lemforder tierods and center link, water pump, belt tensioner, etc.

Again, thanks for all the help and suggestions.

jftu105

Yes take a look at any repair that might work for the crank pulley issue -several ways to skin a cat on that one. It all depends on just how badly off the crank nose is. Sometimes people make a copper woodruff, slot it in and use that to Mig weld against and fill any gaps in the slot. (The copper won’t weld in place and can pop back out again for fitment of a correct new metal key) If done carefully these methods will work. Sure it’s a pain to get access in there but would be worth it if it avoids pulling the whole engine, or scrapping the car for that matter!


As Gerry said though another option if the crank nose is really badly scored, is to find a used motor. I got a full good used m104 motor recently with ancilaries for £120..... and besides the HG issues they suffer from the m104 will run forever if maintained

 

[quicksilver500]

If it was properly torqued there is no way it would just come loose. Maybe if it was the old style with belville washers and they had lost their crown. I don't see a M24? bolt torqued to 400nm just working loose.

Just put a motor in the car. I just did that instead of a headgasket. It's good to have spare parts......now I can do the headgasket whenever.

I have <8 hrs in the swap, pulled the trans and engine out. Swapped some parts over as there were some small differences in my engines.

 

[sheward]

M104 motors are quite readily available here in Atlanta. I see them regularly posted on Craigslist. I'm sure Johnathans looking into this if he doesn't have one at the shop. I would also explore Joes advice on attempting to fashion a replacement keyway first. Johnathan will have the knowledge to know if this may be possible. It could buy you some time at the very least to source a replacement engine.

https://atlanta.craigslist.org/atl/cto/d/94-mercedes-benz-e3-20/6618547724.html

https://atlanta.craigslist.org/atl/cto/d/black-mercedes-benze/6631996283.html

https://atlanta.craigslist.org/atl/cto/d/1993-mercedes-300e-mechanic/6640428548.html I have seen this car as well as bought parts from the establishment. He has had it listed for months.

https://atlanta.craigslist.org/atl/pts/d/1992-mercedes-300ce-parting/6638688381.html

drew

 

[jftu105]

Thank you for all the links. This gives me a perfect excuse to get that cabriolet I have been dreaming about.

jftu105

 

[jftu105]

Drove 6.5 hours to Atalanta and saw the damage in person. The center bolt came loose and the key broke and melted from frictional heat. The hub of the harmonic balancer, which mates to the crankshaft, is badly scored. The crankshaft shaft actually looks good to me, as a much harder material. The key slot still has very sharp edges. Decided to tow the car to Blue Ridge MB and see if it can be repaired with a good harmonic balancer (and, if needed, some custom fitting of the key per JC220). The traffic in Atlanta is not light and a 26 miles drive took an hour. Waited 2.5 hours for the tow truck to arrive.

The car is still drivable for a few minutes and idles so nice because no pulleys are engaged. The car arrived at Blue Ridge after 8 pm. Will discuss with Jonathan tomorrow to see how to save the car. The damage to the crankshaft is really quite minimal, in my opinion. I hope I can save it and further delay my cabriolet dream.

By the way, Blue Ridge MB is a pretty big place. Jonathan is very nice over the phone.

S-H Toh

 

[gerryvz]

Cavernous in size. Especially compared to the old Blue Ridge facility.

 

[jftu105]

At Blue Ridge MB right now. Just talked to Jonathan and I am surprised that he is still so young. His 124 guy, Paul, confirms that it can be fixed and they found the key from another warehouse and the harmonic balancer he has is in a beautiful shape. A new seal and a new serpentine belt will be in. And I will replace the fan bracket later as the bearing is not very smooth.

It would be done today.

Again, thanks guys. I cannot thank you guys enough.

jftu105

 

[jftu105]

OK, the car is alive again. Jonathan and Paul of Blue Ridge MB are as good as what was said on this forum. Will drive the car back to NC tomorrow.

The source of the problem likely was due to a poor job by someone when replacing the front crankshaft seal. It was done before I bought the car. It must not be torqued properly. Six years later, it came loose and took out the woodruff key.

Paul torqued perhaps near 400 N-m and also applied lock-tight for extra insurance. The woodruff key is for positioning and it is too small to carry torque. The torque is carried through the tapered surfaces between the hub and the crankshaft, similar to the mating surfaces between a tool holder and a spindle head of a machine tool.

Should be good for another 10 years, hopefully.

jftu105

 

[gerryvz]

Glad it worked out and you took the advice of folks here, and you saved the car. Jono and his team can and do work miracles on a daily basis.

 

[jftu105]

Drove back from Atalanta to NC, over 350 miles, at speeds between 55 to 80 mph. No problems, at least for now.

The car is saved, with reasonable cost. It has been a long time since last time I paid serious money to a shop for fixing my cars.

Again, thank you all for the great advices and recommendations.

jftu105

 

[jftu105]

By the way, when doing the harmonic balancer, the cooling fan bearing bracket was found noisy and worn. The Rein OEM part is actually a genuine MB. The MB log was ground off and sold as OEM. Get one from FCP Euro for $52 a few weeks ago but it is now discontinued. Blue Ridge MB got one from Worldpac for $85. FCP Euro and other places now only carry Febi for $110 or Uro (I don't touch it) for $52. I ordered two extra Rein brakets through Blue Ridge MB and put them into my other two E320's today. Now all four E320's of mine all have new fan bearing brackets, in addition to good bearings of idling pulleys. The idling does sound better, without weird noises. Idling noise is revealing. I wish I had paid attention to the "Ja-Ja" noise of my blue car during idling which might be due to the loosened center bolt of the harmonic balancer. I could have tightened it to avoid this expensive and effort consuming repair.

jftu105

 

[gerryvz]

I have been under the impression, from reading and closely studying the recent posts and threads over at BW 124 forum, that eco-junk wiring and ChingChangChung parts are the root of all evils with the W124 chassis.

 

[jftu105]

Yes, if you, according to thoese talking heads at BW, changed out the harness and use only MB parts, your car will never fail, except if someone did a bad repair, as in my case.

An interesting observation for the trip back to NC from Atlanta. I and my daughter were each driving an E320 back. I drove the blue one with harmonic balancer repaired by Blue Ridge MB, while my daughter drove the 1995 special edition, which I acquired from Baltimore in early 2017. Before departure, we both filled up the tank. After about 400 miles of driving, my blue E320 had the reserve light coming on plus 5 miles of additional driving. Interestingly, the 1995 SE, the fuel gauge showed just past the second last line before the reserve. In other words, assuming the same amount of the gas at full tank, the 1995 SE can run 40 to 60 miles more, or about 10 to 15% better in gas miliage, or used 2 gallons less gas for the same distance. I am surprised by such a big margin. We followed each other at basically identical speeds.

The blue E320 has a fresh oil change. Both have new genuine MB spark plugs. Both run beautifully with the 1995 SE having more like a new car feeling. Both have fairly new tires. The 1995 have the 16" wheels with 205-55R15 tires and the blue one has 15" wheels with 195-65-R15 tires. Both transmissions are with fresh Dexron VI fluid.

The 1995 SE actually carried a lot more weight with a cargo carrier and a full set of tools.

jftu105

 

[gsxr]

An interesting observation for the trip back to NC from Atlanta. I and my daughter were each driving an E320 back. ... Interestingly, the 1995 SE, the fuel gauge showed just past the second last line before the reserve. In other words, assuming the same amount of the gas at full tank, the 1995 SE can run 40 to 60 miles more, or about 10 to 15% better in gas miliage, or used 2 gallons less gas for the same distance. I am surprised by such a big margin. We followed each other at basically identical speeds.

The fuel economy difference could be a number of things, but I'd start with checking the age of the O2 sensor, and also checking for any sticking brake caliper pistons. It's harder to check the rear brakes, but up front you can spin them by hand and compare one car vs the other. Since you drove together, you can rule out odometer discrepancies.

An extremely remote possibility is the "bad" one has a slightly collapsed fuel tank, and actually used about the same amount of fuel, despite the different gauge readings. If the "bad" car took an extra 10-15% more fuel (per the pump readings at the gas station), you can scratch this one off the list as well, assuming both were filled the same way before & after.

 

[jftu105]

Both O2 sensors were replaced and are good according to Hfmscan. Brakes are all fine. I typically, get 27 on straight highway driving, for 400 miles, it will 14.8 gallons. A full tank should be about 15 to 16 gallons before reserve. Different pumps at the same gas station could put in different amount when it shuts itself off, depending on the gun position. For 400 miles, the blue one used 15 gallons for 26.6 mpg, while the 1995 SE had 16 gallons and is more efficient at getting 28 mpg, or 14.2 gallons for 400 miles. As a result, there are 1.8 gallons left. It is quite reasonable to have 27 vs 28 mpg differences for different E320's.

jftu105

 

[gsxr]

The extra info helps. You are correct, the ~1mpg differece (5%) is reasonable. Your previous post mentioned 10-15% difference, which seemed excessive for an identical trip in nearly-identical cars.

 

[jftu105]

One last note. When I was at Blue Ridge MB, Jonathan showed off his two 500E (abosolutely gorgeous). Paul also indicated that he migrated from 300E, E320, ..., to 500E. It seems that 500E is the holy grail of W124. Cabriolet is just a JV in comparison, while E320 is simply utility. I wish I get to JV first.

jftu105

 

[jftu105]

Had a scary moment with the green MB I rebuilt the head gasket. Coming off highway, waiting at a signal, suddenly, I heard loud noise and the car was shaking like crazy, like something was about to explode. I shut the engine off. Then I turned the key, the noise came on again without engine starting. Repeated it. Same thing. Thinking it was related to AC, I shut AC off. Restart the engine. It was quiet and smooth again. Drove to the parking and turned on the AC on the way, everything was fine. On the way back in the afternoon, it happened again. I finally pull out to a gas station to examine what went wrong.

Anybody wants to guess?

jftu105

 

[nocfn]

A Dead Snake wrapped on the cooling fans?

 

[jftu105]

Right on! Sharp guy. For some reasons, a piece of rubber hose, 1/2" in diameter and one inch long, got into the auxilary fan in front. I had no clue how it got there and where it came from. It knocked out 8 out of 10 fan blades and some blades also stucked inside, blocking the remaining blades. I am surprised how much shaking the auxilary fan could produce. Really scary when it happened. I removed the fuse to the auxilary fans and drove home without further incidents. Will replace it. Never had this happened before.

 

[nocfn]

So where did the hose come from? PS SLS Tranny coolers OHMY!

 

[jftu105]

No clue. It was not a working hose, just a short piece, seemly cut from a long piece. The only possibility I could think of is that it might come from some debris while I was doing the head gasket replacement. However, it was several months ago. How did it just show up and destroy my auxilary fan now? No clue. I have no coolant leak of any kinds. Now I think of it, having fans in front of the radiator to push air is not a good idea, as debris could get there more easily. Walking in junkyard today to get a replacement fan, I notice that not many cars have auxilary fans installed in front. I also noticed that 1997 E320 have only one real fan and use a belt to drive a smaller fan next to it. Cost cutting is apparent for W210.

S-H Toh

 

[nocfn]

Was it small enough for some pin head to stick it thru the grille just for sick kicks?

Or was it the fabricated hose that acts like a vibration buffer for the radiator that dislodged?

 

[jftu105]

Really no clue and it was not easy to get this hose piece out. It was large enough. It is not something used for any real purposes, just a short hose cut from a large hose.

Got a new fan in and it works but the other fan is not spinning. I will just go with one fan for now and put another one in the future.

 

[nocfn]

Be sure to post some pics, that always helps for reference and when you replace the fan, perhaps a pictorial HOW-TO is in order. &delta is a member in the SC border of NC and he sees 124 in the yard often, if you don't have one close hit him up to snag the complete assembly off a donor as they rarely go bad.

 

[jftu105]

Pelicanparts has a detailed how-to article on the replacement of the auxilary fan. Here is the link to it,

https://www.pelicanparts.com/techar...acement/19-WATER-Auxilary_Fan_Replacement.htm

I will contact &delta if I need something which I could not find.

Thanks.

 

[gerryvz]

I think he means 7delta, one of TFTSNBN 126 forum guys.

 

[nocfn]

I think he means 7delta, one of TFTSNBN 126 forum guys.

Correct - 7delta and he is more of lurker here and provider of parts than anything.

 

[jftu105]

After putting in an auxiliary fan to replace the one damaged by debris, I noticed the other one is not spinning at all. I did not want to drain the coolant and remove the radiator, as suggested by the DIY by pelicanparts, to replace the other fan. I went to my old notes because I remember that I took out the aux fans from the front before without removing the radiator.

As it turns out, if you remove the front bumper, you will have a lot room to work with and you can remove many parts in front which block the way. The job is easier. You still loosen the radiator and AC condenser to move them toward the engine but no need to take the radiator off.

Put in a new fan. The old fan is dead perhaps due to worn out brushes because the impedence is infinity between the wires.

jftu105

 

[jftu105]

MOT purge valve for gasoline vapor pressure control.

I wrote a detailed report on this problem and posted on MB forum in Dec 2015. Now fast forward 3 years, I realized the purge valves of my four E320 are all dead again, not giving a pulsing sound, dadada.., when the engine temperature is above 80C. Had to remove them and knock them against my table to remove carbon deposits. Sprayed some cleaner and then check the solenoid. When applying 12V to it, I could hear a click. Put everything back and drove around. Now, the dadada sound is back.

This little purge valve keeps the gas tank pressure from going too high and recycles it to the engine to burn. Typically, it got stuck closed and the gas pressure could build up. When you open the cap of the fueling hole, if you hear a very loud swishhhh, the pressure could be too high. Check this little valve. It needs constant attention, apparantly.

jftu105

 

[gsxr]

AFAIK... it's normal for the fuel tank to be (slightly) pressurized on the 124 chassis. When you remove the cap, there will the "swishhhh" sound as air is released. This is not vacuum, as some people think - or at least should not be vacuum! Vacuum in the tank is bad, it can cause the tank to collapse, and in some cases crack the tank so it leaks. Pressure in the tank is ok, and it can help keep fuel stable over a longer period of time. My 124's will hold the pressure in the tank for at least 6-9 months, maybe longer (I've never tested to see how long it will hold).

Interestingly, the 210 chassis has a totally different venting system and never builds *any* pressure in the gas tank. Something about preventing vapors from escaping to the atmosphere.

 

[jftu105]

AFAIK... it's normal for the fuel tank to be (slightly) pressurized on the 124 chassis. When you remove the cap, there will the "swishhhh" sound as air is released. This is not vacuum, as some people think - or at least should not be vacuum! Vacuum in the tank is bad, it can cause the tank to collapse, and in some cases crack the tank so it leaks. Pressure in the tank is ok, and it can help keep fuel stable over a longer period of time. My 124's will hold the pressure in the tank for at least 6-9 months, maybe longer (I've never tested to see how long it will hold).

Of course, I am referring to excessive pressure in the gas tank. The purge valve is designed to regulate the pressure.

jftu105

 

[jftu105]

Here is an image of this purge valve. This particular one is not for E320, 1994-5, but it can be easily adapted.

https://www.autohausaz.com/pn/00047...MIvcOPodGf4AIVEODICh1SngUyEAQYASABEgIxC_D_BwE

jftu105

 

[jftu105]

Finally, got the MOT of each of my four E320 fixed up. All of them stuck, either closed or open. If stuck closed, the gas tank pressure could go excessive. If stuck open, it is a form of vacuum leak, affects idling. One end of this MOT purge valve is connected to intake vacuum (output) and the input is to the carbon canister. The MOT valve is actually a potential vaccum leak source but rarely got attention. In the process of fixing them all up (last time three years ago), I noticed a few bad connections, resulting vacuum leak. Some of them apparently led to not as smooth idling (stillness). Now, all four E320 are idling beautifully at D.

When I took off these MOT valves and banged them, lots of carbon particles came out of the input side. Most of them were revived. I had to throw away one as it won't work no matter how much I tried to revive it.

Once the coolant temperature hits over 80F, you should hear dadada.... of the MOT valve. ECM controls the MOT to pulse it open and close at a fast rate about 75 Hz if I remember it right. That's why you will hear dadadada....

jftu105

 

[Stegel]

My first ever post here - this forum is a fabulous resource for anyone running youngtimer MBs, and Gerry, this thread is a Godsend for 104 owners! Many thanks to all contributors.

The head gasket is ok in my car, but it has leaks from the front crank seal, the oil filter housing and the timing cover, and while I’m in doing the latter I thought I had better check the chain stretch. As per Gerry’s car, the inlet sprocket hole is well above the deck, to an extent that suggests it’s a “cog out” - pulling the chain around 1 tooth sees the hole line up near perfectly. However, the exhaust sprocket, at TDC, is lagging behind meaning that while I can get an Allen key in the hole, it is at a slight angle, reaching down below deck height. All this probably only means a couple of degrees, but certainly the chain is stretched and at 163k miles and no record of a change it’s not surprising, so a new chain is the next task - I drove the car into the garage a couple of weeks ago just to check for oil leaks pre-MOT, and it’s now in several dozen pieces and the parts list grows by the evening!

 

[Stegel]

Several boxes of parts from MB later and I’m off. The bodging is evident now I’m digging - what looks like bathroom sealant used on all the sealing surfaces of the top timing chain cover, and judging by the cheesy texture in bolt holes, it doesn’t like contact with oil. There was a 15mm wide fillet hiding behind the crossover pipe, but looking at the caked on oil below that level it (not surprisingly) wasn’t doing much good. Careful cleaning of the Bermuda Triangle coming up.

I’ve hit a snag though. I’ve got the generic MB copy pin puller which comes with an M8 and an M6 tip. The pin holding the guide through the top cover refused to accept either, so I thought I’d try an M5 bolt, which went in fine. Using an oversized nut and socket as an extractor I was making great progress until I realised it was simply pulling out of the bolt, not the pin. The M5 bolt now wobbles about, and I’m now thinking (ref the bodged sealant etc.) is the pin actually M6 thread, and did the bathroom sealant bodger used a drift or centre punch to drive in the pin, burring over the start of the thread? I’ll have a poke about, but I’m wondering about a quick whizz with an 8mm drill bit to clear out the burr?

 

[gsxr]

Can you chase the threads in the the pin with a tap and re-try with a proper bolt?

 

[Stegel]

Thanks, looks like that’s what I’ll be doing. I’ve just gently run a drill bit in the hole, and the way it bumped around at first suggested burring. The M6 tip refuses to bite though. Unfortunately while every other tap and tap holder is in the correct drawer, M6 taps are conspicuous by their absence - standard form for a holiday weekend! - so I’ll leave that for now and return when I can pick a couple up.

 

[Stegel]

I doubt I’m adding much to the collective knowledge on the thread with this, but by way of an update.

I bought a set of Sheffield’s finest M6 taps and they made light of cleaning up the pin’s bore. Unfortunately the not particularly cheap but poorly made Chinese pin puller snapped after about half a revolution of “pull”. The drill and taps came out again, but using a plain M6 bolt, nuts and washers to contrive a puller failed to persuade the pin to move - I could sense another “snap” coming on (and perhaps I’m being unfair on the Chinese pin puller’s quality). I’ve taken the front cover off to reveal bathroom sealant everywhere - including all surfaces of the cover, all over the green bottom seal, around the pin and even on the front facing side of the inlet side chain guide - so perhaps the whole thing is gummed up with a hitherto undiscovered property of bathroom sealant. I’ve given it a stern looking at and turned the garage light out while I contemplate an escalation in weaponry.

 

[nocfn]

Bathroom sealant, the acidic type that promotes oxidation on metal?

 

[Stegel]

Possibly - there are two types (in the UK, anyway) of silicone mastic, acidic acetoxy (smells like vinegar) and neutral cure (my father in law, pre-retirement, owned a mastic sealing business, so I’d be failing him if I didn’t know that!). There is some brown staining beneath the mastic, but it cleans off reasonably easily, so perhaps it is neutral cure. It’s highly elastic, which leads me to suppose bathroom sealant. Whoever did it filled the groove in the top of the lower timing cover, bedded the green MB seal into it, then splodged more on top. It did not adhere to the green seal, and there’s oil between mastic and seal above and below. All the bolts are caked in what looks like cream cheese when withdrawn. Lots of cleaning up to do!



The removal of the dowel pin that passes through the top timing cover still evades me. I had no intention of changing the chain at the start of this, with an oil leak from the crank front seal the biggest task. Most ancillaries are removed now, so I’m going to plough on, remove the harmonic balancer etc., the lower cover and guides, and then plan to thread the outside of the pin (it’s 8mm dia) with an M8 die and use a small slide hammer with an 8mm thread I have, connected to a threaded coupler, to withdraw it (hopefully). I have new guides etc. from MB all ready to go on.

It’s moved on from a top end overhaul and I’m keen not to hijack the thread, but would a few photos of the lower case removal etc. be of interest?

 

[JamesC]

Re: M104 / W124 Top-End Rebuild

First, I removed the grommets from their small MB boxes. These grommets seal the gap where the plastic air crossover tube acquires PCV vapors into the intake air that is passing from the air filter and MAF sensor, to the ETA to be admitted into the engine.
View attachment 21444 View attachment 21445 View attachment 21446 View attachment 21447


Then, I pressed the grommets into the freshly painted valve cover.
View attachment 21448 View attachment 21449 View attachment 21450


Here's a view of the both grommets, installed.
View attachment 21451

Hello all,

I appreciate any help anyone can provide on getting the above grommets/crank case / valve cover breather gaskets OUT of the valve cover Thanks to Gerry for the excellent tutorial.

**EDIT, apologies I thought it would quote with photos. This is part MB-1040160980



Newly imported G320 for my wife and in changing plugs saw some oil in the barrels. Replaced the Valve Cover gasket, spark plug barrel gaskets, VC bolt gaskets, half moons, brittle vacuum lines and then also did all coils, plugs and lines as well since we were there. This breather gasket is the most tedious part of the process so far!

I've partially destroyed one of the gaskets. It has an interesting spring impregnation but otherwise seems unremarkable. I've tried several different things without success. Help! Thank you!

James and Gabriela
Dallas TX

 

[bclifton]

Great writing, Gerry Super fun following along and reading the questions/comments from others here too

I found this post after purchasing my first W124, a 1993 300E w/ the M104. I had to replace the water pump which was trashed and am now looking at the valve cover gaskets. During the repairs, I've been crossing my fingers there isn't a head gasket issue. I found this thread when trying to understand all the "while you're there"s you might run into while doing the head gasket. As a novice mechanic, I have a lot less confidence jumping in there! Car has 152k miles on it and I've tested for combustion gases in coolant, seems OK for now. I'm thinking about pouring in some K-Seal to buy some time (would love to get to 200k or 250k miles before head gasket)

Part numbers (bottom of page 2) were a massive help - just for the valve cover gasket job I'm about to do, I didn't think about replacing the rubber o-rings under the bolts (104 016 03 64), the air breather gaskets (104 016 09 80)... and the dipstick was a good one I'll do too. Thanks for documenting so thoroughly