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

[liviu165]

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

Hi @bclifton, good to read your posts (again). I wish you still had your C126 so we can get involved in the same threads, but I guess you had your reasons to sell it. Great looking car you made from that 560SEC!

Anyway, you'll find very knowledgeable guys here for your W124, a much different crowd from the older days.

 

[gerryvz]

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

The only way to do it is to jump in and tackle it head on ! It's how we learn and grow, by stretching our boundaries. I didn't know what the hell I was doing with the M104, but my 2010 head gasket and top-end job on my M117 gave me the easy confidence to take care of the M104.

The rubber rings under the M104 valve cover bolts are SUPER important to replace along with the main valve cover gasket. If I remember correctly, there are a couple of "half moons" at the back-side of the M104 engine valve cover, that have to be installed into the top of the cylinder head. Make VERY sure those two half-moon pieces are correctly emplaced before putting the actual magnesium valve cover + new gasket down.

I would not add any additives to the engine. Shan't need them, really. Personally, it may not be a bad idea to replace the three coil packs and wires whilst re-assembling things, as well. Particularly if they are original Bosch coil packs with the light blue labels on them. On the three M104s I've owned, I've had coil packs go bad on all three of them. I keep a few emergency spares from the wrecking yards in case I need them.

As far as your engine and head gasket -- the M104s, if on the original head gaskets, often need new ones by the 125K mark. At 150K on an original M104 head gasket, I'd be closely monitoring for any engine oil usage. By 200K, it's HIGHLY likely that any original head gasket will be leaking. My former wagon was over 200K when I did the head gasket in this HOW-TO, but I believe it had actually already been done once before I bought the car.

My 1995 G-wagen, which also has an M104, currently has 128K miles and is getting ready to enter the "sweet spot" when it will someday need a new head gasket. So it is likely that I will be doing this job someday again. Fortunately I've documented it Some idiot past mechanic used RTV in replacing the valve cover, so when I pull that off, I have one heck of an RTV cleanup job to do.....

The good thing about the M104 head gasket replacement job is that there is PLENTY of room to work under hood; and not that much is needed in the way of special tools (mainly, the MB socket for removing the head bolts). If you do end up doing it, you will find plenty of old and brittle and dilapidated "soft" parts underhood, that you will want to replace. Also, unlike the M117, there's only ONE cylinder head (albeit damned heavy) to hassle with !! But, you can cross that head gasket replacement bridge when you come to it.

 

[gerryvz]

Hi @bclifton, good to read your posts (again). I wish you still had your C126 so we can get involved in the same threads, but I guess you had your reasons to sell it. Great looking car you made from that 560SEC!

Anyway, you'll find very knowledgeable guys here for your W124, a much different crowd from the older days.

@bclifton .... @liviu165 is just being modest. He's single-handedly raised the level of technical information and HOW-TO expertise on this forum on his own shoulders over the past 18 months.

 

[bclifton]

Hi @bclifton, good to read your posts (again). I wish you still had your C126 so we can get involved in the same threads, but I guess you had your reasons to sell it. Great looking car you made from that 560SEC!

Anyway, you'll find very knowledgeable guys here for your W124, a much different crowd from the older days.

Great to see you here Roy I loved that W126; I'm still trying to find time to document all the work I did on it. I have a site up, The Mercedes-Benz W126

Long story short, my wife was always giving me crap about the car and she wanted me to ditch it . It was an older car (1991) and the A/C isn't on par with newer cars. The CL63 (C216) that I got to replace it has been a good car, but it's not the same. I believe the SEC went to a person in New Jersey - have been looking to see if that person signs up anywhere so I can follow along

The only way to do it is to jump in and tackle it head on ! It's how we learn and grow, by stretching our boundaries. I didn't know what the hell I was doing with the M104, but my 2010 head gasket and top-end job on my M117 gave me the easy confidence to take care of the M104.

The rubber rings under the M104 valve cover bolts are SUPER important to replace along with the main valve cover gasket. If I remember correctly, there are a couple of "half moons" at the back-side of the M104 engine valve cover, that have to be installed into the top of the cylinder head. Make VERY sure those two half-moon pieces are correctly emplaced before putting the actual magnesium valve cover + new gasket down.

I would not add any additives to the engine. Shan't need them, really. Personally, it may not be a bad idea to replace the three coil packs and wires whilst re-assembling things, as well. Particularly if they are original Bosch coil packs with the light blue labels on them. On the three M104s I've owned, I've had coil packs go bad on all three of them. I keep a few emergency spares from the wrecking yards in case I need them.

As far as your engine and head gasket -- the M104s, if on the original head gaskets, often need new ones by the 125K mark. At 150K on an original M104 head gasket, I'd be closely monitoring for any engine oil usage. By 200K, it's HIGHLY likely that any original head gasket will be leaking. My former wagon was over 200K when I did the head gasket in this HOW-TO, but I believe it had actually already been done once before I bought the car.

My 1995 G-wagen, which also has an M104, currently has 128K miles and is getting ready to enter the "sweet spot" when it will someday need a new head gasket. So it is likely that I will be doing this job someday again. Fortunately I've documented it Some idiot past mechanic used RTV in replacing the valve cover, so when I pull that off, I have one heck of an RTV cleanup job to do.....

The good thing about the M104 head gasket replacement job is that there is PLENTY of room to work under hood; and not that much is needed in the way of special tools (mainly, the MB socket for removing the head bolts). If you do end up doing it, you will find plenty of old and brittle and dilapidated "soft" parts underhood, that you will want to replace. Also, unlike the M117, there's only ONE cylinder head (albeit damned heavy) to hassle with !! But, you can cross that head gasket replacement bridge when you come to it.

There really is no substitute for experience The water pump replacement was definitely involved - I learned a ton there. I started a video series for anyone interested in following along. Will update when I do valve cover gaskets over the next 2 days; waiting on some parts

https://www.youtube.com/playlist?list=PLc713pFuJyE3CvCQGHOeF5KUDNDP_Cjn-

My mother-in-law has been borrowing the 300E for the past 2 weeks and really loves it - I think we'll sell it to her (at cost) after I wrap up a few more jobs. She's just down the street, so I'll see it (and work on it) again. I've been really impressed with the W124 platform- lots of thoughtful updates to things which bug me about the W126. I'll be keeping an eye out for a 400E / E420 for sure A proper 500E / E500 would be amazing (especially with documentation/support here) but prices have gone up quite a bit - and large amounts of deferred maintenance might get me back in trouble with Mrs Clifton again

 

[bclifton]

Looks like I'll be keeping the W124 after all! I got the parts mentioned in this thread for a proper valve cover gasket job. Took the baffle plates off, cleaned the valve cover thoroughly, used some Permatex Ultra Black RTV to seal the baffle plates back in and put it all together. Captured some videos of the experience here

Ran into two problems:
1. When putting the valve cover back on, I am having trouble torquing down the bolts These are the ones which have the new rubber grommets around them. Most of them tighten up just fine - but there are probably 4 of the 12 which engage with the threading, start to tighten, and then can be turned forever. If you take out the spacer (that the bolt goes through) and just hand tighten the bolt into the hole in the head, it engages perfectly fine and tightens up until you can't turn it anymore. Almost feels like some of the bolts might be too short and aren't making it into the threading enough turns - will have to see if replacements are available

2. When taking the valve cover off, you need to move the wiring harness out of the way. I suspect when I did this, I cracked wires inside the harness and near the coil. In the above video (2nd one) you can see the exposed wires from the bio harness. After plugging this back in and running it, I think I blew the #6 coil. Video uploaded here showing the misfire, a hacky electrical tape fix, and then finding the original 6 Nov 1992 wiring harness (not captured on video: me cussing a lot and kicking boxes on the floor)

I found another great thread on here on 500eboard which I've scraped part numbers from and am placing an order now (I use mbpartscenter.com; MB of Scottsdale here locally):

HOW-TO: Replacing M104 coil pack & spark plug boot | Off-Topic Discussions

Recently, my wife's 1995 E320 wagon, which has 187K miles on it and runs perfectly, starting having a few problems: occasional difficult (stumbling) starting, particularly when not driven for 2-3 days one day, extremely rough running and rotten-egg smell coming from the exhaust The...

www.500eboard.co

Basically looking to replace the other two ignition coils and spark plug wires. Also ordered (on eBay) a used wiring harness (dated 2010, Delphi) in great shape for $280 (appropriate price for a 300E 2.8) and I'll be trying to do that next along with the coils. Even though these are some not fun challenges, I'm grateful for these forums. Thanks again

 

[gerryvz]

I've got a couple of used wiring harnesses for a fraction of that ... look in the OFF TOPIC posts classifieds.

FOR SALE - Upper Wiring Harness for E320, without ASR, $175 shipped | Off-Topic Discussions

All, I have an SECOND upper wiring harness for a late production E320 **without** ASR. It came off of a 1993 E320. It is NOT appropriate for E320 models with ASR. MB part number is 124 440 56 32 The production date is November, 2011. All connectors are in great condition, no split plastic...

www.500eboard.co

FOR SALE - Upper Wiring Harness for Late E320, without ASR, $175 shipped | Off-Topic Discussions

All, I have an upper wiring harness for a late production E320 **without** ASR. It came off of a 1994 E320. It is NOT appropriate for E320 models with ASR. MB part number is 124 440 56 32 The production date is February, 2003. All connectors are in great condition, no split plastic, etc...

www.500eboard.co

 

[gsxr]

1. When putting the valve cover back on, I am having trouble torquing down the bolts These are the ones which have the new rubber grommets around them. Most of them tighten up just fine - but there are probably 4 of the 12 which engage with the threading, start to tighten, and then can be turned forever. If you take out the spacer (that the bolt goes through) and just hand tighten the bolt into the hole in the head, it engages perfectly fine and tightens up until you can't turn it anymore. Almost feels like some of the bolts might be too short and aren't making it into the threading enough turns - will have to see if replacements are available

Sounds like stripped threads at the top of the bolt hole. If so, you either need a good replacement valve cover, or use Time-Sert thread repair.

 

[Gmach]

Gerry I am about to replace the tappets / lifters on my 97 E320 M104.
Do you know of a link to a DIY or to a workshop manual.
I need to know the correct sequence for removing the cam bearing caps.
I seem to remember there is a specific sequence or you risk the cam breaking.
Thanks.

 

[gsxr]

Try this one.

Mercedes Benz Model 124 - M104 Maintenance Manuals

 

[Gmach]

Thank you Dave.

 

[mikkelrev69]

Re: M104 / W124 Top-End Rebuild

From my parts list, these are the two sealants that MB specifies for the job:

View attachment 23153

View attachment 23154

The orange anaerobic sealant is used for both the timing cover sealing surfaces, and the intake cam solenoid. The item being sealed should be installed within 10 minutes of this sealant being applied.

The clear RTV sealant is used for the "dots" or "globs" at the ends of the timing cover seal. It is best to install the part being sealed and let this cure at least overnight before continuing further. Meaning install the timing cover and seal (with the globs of sealant) and wait overnight to let it cure.

Cheers,
Gerry

Hi.
Old thread but still excellent and relevant. Did part of this my self on my '96 S124 E280 (M104.942). Has the very latest specs made Nov. 1995.

Last time I sealed upper timing cover I used Loctite 5900. Worked well and without leaks after another 30.000 mls. Now I have to reseal the crank case cover due to leaks and have been looking into what sealants are available and recomended..

Daimler EPC online lists
002 989 45 20 as valid RTV sealant still today and can apart from obscure Ebay shops be ordered from a certain German Taxi Teile web shop I always order genuine Mercedes parts from to reasonable prices. You' ll find it easily

002 989 47 20 OTOH is obselete and is replaced by 001 989 89 20 (10)

Elring has a red anaerobic sealant 470.200/461.681 also called AFD 2018. This is spec'ed OE 001 989 89 20 10 so it's a direct replacment for the orange stuff 002 989 47 20.

Mercedes dealers though lists just the 003 989 98 20 (10) as the only engine sealant in use. This is for later and current models with tighter tolerances (and gaps) I guess and I rather trust Daimler EPC which tells me what to use for my M104

 

[gsxr]

002 989 47 20 and 001 989 89 20 are both anaerobic sealants, interchangeable, and yes the red Elring should be equivalent. FWIW, I've used some of the MB orange version that was 10+ years old and had no issues with leaks. YMMV.

003 989 98 20 is allegedly the same, or very similar to, Loctite 5900. This is supposed to be excellent sealant but I'm not sure I would use it for all applications where anaerobic was originally specified. The difference is, anaerobic sealants allow the part to be removed easily. Loctite 5900 is more similar to an RTV and can act as adhesive, "gluing" the parts together, possibly making it difficult to remove in the future. Be careful if you replace anaerobic with 5900.

Oh, and Permatex Right Stuff is supposed to be similar to 5900... not the same, but close enough. I've used Right Stuff several times with good success, from the pressurized canister. Keep in mind that 003 989 98 20 has a short shelf life (12-18 months max?) and once expired, it takes WEEKS to set up... fresh stuff sets overnight, I believe. That alone is a big hassle for DIY'ers who may take years to use up a tube of 003 989 98 20.

 

[mikkelrev69]

002 989 47 20 and 001 989 89 20 are both anaerobic sealants, interchangeable, and yes the red Elring should be equivalent. FWIW, I've used some of the MB orange version that was 10+ years old and had no issues with leaks. YMMV.

003 989 98 20 is allegedly the same, or very similar to, Loctite 5900. This is supposed to be excellent sealant but I'm not sure I would use it for all applications where anaerobic was originally specified. The difference is, anaerobic sealants allow the part to be removed easily. Loctite 5900 is more similar to an RTV and can act as adhesive, "gluing" the parts together, possibly making it difficult to remove in the future. Be careful if you replace anaerobic with 5900.

Oh, and Permatex Right Stuff is supposed to be similar to 5900... not the same, but close enough. I've used Right Stuff several times with good success, from the pressurized canister. Keep in mind that 003 989 98 20 has a short shelf life (12-18 months max?) and once expired, it takes WEEKS to set up... fresh stuff sets overnight, I believe. That alone is a big hassle for DIY'ers who may take years to use up a tube of 003 989 98 20.

5900 is oxime silicone and in fact RTV not just similar. Its close to 5970 alkoxy silicone RTV but is stronger and more flexible. The point of using anaerobic sealants is rather its curing properties not if it glues hard or not. Anaerobics doesn't harden until airtight metal to metal contact is established. Excessive sealant spill inside casings wont harden and risc clogging oil channels. It will be flushed away uncured with the oil. Anaerobics can have pretty strong gluing properties just as well, like the Elring El-Liq73 anaerobic sealant. I read it was used on 911 gearbox halfes which has to form an extremely rigid connection.

WIS sealant specifications for upper timing cover seems to be different on CIS/LH engines vs HFM engines. 0029894520 RTV in the U-gasket corners for both (I assume because of the need for filling big gaps and flexibility because of joint movements. For HFM engines it is listed as cover surface sealant as well. CIS/LH engines OTOH should use 0029894720 anaerobic on cover surfaces. Is this typo or doesn't HFM engines have the same need for anaerobic for some reason? Are there any differences other than the distributor and cam seal?

The only reason for me to purchase anaerobic 0019898920 was to use it on the lower timing cover. I planned to use RTV only on upper timing cover as specified in WIS. Anaerobic can't be used in the joint behind the U-gasket anyway. 0039899820 I'm staying away from.

 

[Seangbadee]

Re: M104 / W124 Top-End Rebuild



Here's a post with some random notes and musings I've been thinking about for the past couple of days, as my top-end rebuild progresses. I hope y'all find these of interest, and some relevance to the E500E world.

First, the first box from my third (and next to last) parts order rolled in today. Inside the box were my 28 new cam bearing cap bolts, which (per your thought Michael) are exactly the same as the ones that are currently holding the bearing caps onto the head. I also received 11 of the 14 new head bolts -- I assume the other three will be in the second package, arriving from MB's Carol Stream, IL warehouse tomorrow (Tuesday). As I'm now on Christmas holiday for the rest of the year, I've plenty of time to enjoy working on the car out in the shop.

One of the parts that came in today's box were the copper exhaust manifold nuts. These nuts are a "one-use" nut, meaning that they are discarded upon removal from the car, and new ones are supposed to be used. The interesting thing about them is that they are shaped slightly differently than most other nuts. Take a look at the photos below. Can you see what is different from most ordinary nuts?
View attachment 21509 View attachment 21510


I've received a couple of PMs and comments here from folks who are interested how I keep records of what I do. Well, besides the photographic record, I maintain a log in an ordinary student composition notebook (the ones with the black and white speckled cover) with all steps performed, as I do them. I also record the following things, on separate pages and in the margins:

• time worked during each day's session
• description of any parts broken/cracked during removal, that require replacement
• number of cups of coffee and 60oz sodas consumed during working hours
• comprehensive list of part numbers & descriptions for parts orders
• any handy notes, such as torque values, part quantities, thread pitches, etc. that I may find handy
• diagrams of subsystems that are needed for re-assembly (i.e. vacuum line or wire bundle routings & placement)

Here are a couple of photos of some of my notes from this project:
View attachment 21511 View attachment 21512


Next, one of the things I'll be doing is replacing the timing chain. I had ordered (via AHAZ) an IWIS chain (MB OEM) and I opened it up to see what kind of master link it had -- there are a couple of different kinds. Indeed, it is the "plate" type and I am going to need to borrow my mechanic's chain riveter/press to install the new chain - basically to crimp down the end links to keep the center and edge plates in the proper place on the chain. It's a fairly easy operation, but the tool is very specialized, and last I checked around $800 from MB. It will be basically an overnight use for me -- my mechanic doesn't use it all that often.
View attachment 21513 View attachment 21514 View attachment 21515

And here are a few photos of me on my continuing clean-up of the pistons. This is a view of cylinders #3 (right) and #4 (left) at the beginning of (#3) and before (#4) the piston crown cleanup process. Basically this is a lot of elbow grease and patience, and takes about 30 minutes to clean 80-90% of the baked-on carbon from the piston. Most of this time you are hunched over the fender or radiator, or in my case sitting on top of the ABS pump (it's nice and flat, though not very comfortable) and leaning over the now exposed block.
View attachment 21516 View attachment 21517 View attachment 21518

And lastly..... an investigation of the wiring in the cable for the ORIGINAL ETA that was in the car. This ETA, as you can see from the first photo below, is dated November of 1994, so was the original unit. It was working just fine when removed, but it was only a matter of time before it would have shorted out and caused problems. And after opening it up ... I am doubly glad that I did this job now. Now remember, this ETA had ONLY been removed and had been fairly gently handled since removal, spending most of its time sitting on the garage floor.

You can see what the situation was, when I slit open the wiring cable. The photos pretty much speak for themselves. To say I was living on borrowed time, is an understatement.
View attachment 21519 View attachment 21520 View attachment 21521 View attachment 21522 View attachment 21523


This ETA biodegradeable wiring situation shown above (both wiring in the external cable bundle and inside the housing) is also a common problem with the E500E, given enough time and mileage.

Just wanted you guys to see this.

Cheers,
Gerry

Gerry,
After discovering the biodegradable wires in my lower harness and reading through this post, I am really concerned about my ETA and its wiring. Is there a way to remove the ETA without going through all the steps that involve removing the intake manifold?
Cheers,
Sean

 

[gerryvz]

Gerry,
After discovering the biodegradable wires in my lower harness and reading through this post, I am really concerned about my ETA and its wiring. Is there a way to remove the ETA without going through all the steps that involve removing the intake manifold?
Cheers,
Sean

If your wiring harnesses are bad, then it is almost GUARANTEED that your ETA wiring is going to be bad, as well.

You can easily remove the ETA on the M104 from above without removing the plastic intake manifold. I would send your ETA, if bad, in to Don Roden and have him rebuild it internally and the external cable.

I have removed many of them from M104 cars in wrecking yards (and keep a spare for my G320).

 

[Seangbadee]

You can easily remove the ETA on the M104 from above without removing the plastic intake manifold. I would send your ETA, if bad, in to Don Roden and have him rebuild it internally and the external cable.

My mother always reminded us that "an ounce of prevention is better than a pound of cure". I would rather have it refurbished before 'Grace' goes back on the road again.
Thanks mate
Sean

 

[gerryvz]

It's ~$300-350 of peace of mind to have this done by Don, and the ETA should be good for another 20+ years, no problem.

 

[Seangbadee]

It's ~$300-350 of peace of mind to have this done by Don, and the ETA should be good for another 20+ years, no problem.

Would you happen to have the contact information for Don?

 

[gerryvz]

Would you happen to have the contact information for Don?

FYI - Electronic Throttle Actuator (ETA) Rebuild | M119 Engine

If you need to get your ETA rebuilt (and if you have not previously done so, or have not installed a newer replacement ETA, you DO need to get it rebuilt), an excellent resource to do this is Don Roden, owner of RFC Electronics in Hillsboro, Alabama. Don is hyper-knowledgable about ETAs, is a...

www.500eboard.co

 

[Seangbadee]

FYI - Electronic Throttle Actuator (ETA) Rebuild | M119 Engine

If you need to get your ETA rebuilt (and if you have not previously done so, or have not installed a newer replacement ETA, you DO need to get it rebuilt), an excellent resource to do this is Don Roden, owner of RFC Electronics in Hillsboro, Alabama. Don is hyper-knowledgable about ETAs, is a...

www.500eboard.co

Thank you

 

[Seangbadee]

Re: M104 / W124 Top-End Rebuild

After that, it was time to install the front timing cover "for real." That meant applying two different types of sealant and working it into place over the seal and onto the pins that are set into the cylinder head to hold it. First, I opened the tube of clear MB RTV sealant, which was used in a big "dot" (as MB calls it) or "glob" that sits in the area between the end of the green rubber seal, and the cylinder head.

Per MB instructions, I put the sealant down BEFORE re-installing the green rubber seal, although after the seal was installed I added a couple of more globs of sealant at the gap.
View attachment 22639 View attachment 22640 View attachment 22641 View attachment 22642 View attachment 22643 View attachment 22644


Then, I added a small amount of motor oil to a small "cap" container, and per MB instructions coated the leading edge of the green rubber seal with motor oil, using a Q-Tip (scored from my wife's make-up drawer). This is supposed to ease the travel of the bottom of the timing cover into the correct place
View attachment 22645 View attachment 22646 View attachment 22647


After oiling the seal, I applied some of the special orange MB anaerobic sealant to the metal sealing surfaces on the inside of the timing cover, where it seals up against the cylinder head. This is the special orange MB sealant that is made from esoteric ingredients like a rare breed of Japanese satsuma (miniature orange), and pulverized koala-bear claws. And YES, I did install the round red rubber o-ring in the center of the timing cover around the return water pipe....
View attachment 22648 View attachment 22649


After fitting the cover into place manually, I inserted the six bolts that held it to the cylinder head, and tightened them by hand. Then I torqued them down to their correct 21 Nm of torque, and double-checked that.
View attachment 22650 View attachment 22651 View attachment 22652 View attachment 22653 View attachment 22654


Here's what the front of the motor looked like with the timing cover installed.
View attachment 22655


Here are a few close-up shots of the timing cover rubber seal, after everything was torqued into place.
View attachment 22656 View attachment 22657 View attachment 22658


And the metal-to-metal mating surface between the cover and the cylinder head.
View attachment 22659


The next task was to install the cam solenoid to the outside of the timing cover. It was dirty (although not noticeably leaking upon removal) so I cleaned the old sealant off the back of it, and re-installed it with the three 5mm Allen bolts that held it to the timing cover. I sealed it with more of the special orange/citrus-smelling koala-claw goo.
View attachment 22660 View attachment 22661 View attachment 22662 View attachment 22663 View attachment 22664 View attachment 22665 View attachment 22666


The last task of the night was to begin to install the new timing chain tensioner. The main thing here was to make sure that the outer housing of the tensioner didn't get cross-threaded where it went into the block. I was able to thread it in by hand, giving me excellent "feel" to ensure it was threaded correctly. Tomorrow I will finish the timing chain tensioner install, and this outer housing will need to be torqued into the block at a torque value of 80 Nm.
View attachment 22667 View attachment 22668 View attachment 22669 View attachment 22670 View attachment 22671 View attachment 22672


Hope you found this installment to be educational !!

Cheers,
Gerry

Gerry:
Are these sealants still available? When I took my cover off this afternoon, the edges and the bermuda triangle were coated with black, not clear sealant or the orange one. Do you have any other recommendations.
Sean

 

[gerryvz]

Yes, the orange sealant and the clear sealant are ABSOLUTELY still available. I got a new tube of the orange stuff last year for my M119 Top-End Refresh. The clear stuff should also be available.

Many mechanics use RTV or other sealants. I recommend using what MB specifies -- especially the orange anaerobic sealant. I believe that it is made by Loctite, and it is avaialble on the aftermarket via Amazon and other sources if you don't want to get it from MB. A good forum search along the lines of "orange anaerobic sealant Loctite" will give you the proper Loctite product number. If I remember correctly, it may be called Loctite 5900 or something? HOW-TO: M104 / W124 Top-End Rebuild | "HOW-TO" Tutorial Articles

 

[Seangbadee]

Yes, the orange sealant and the clear sealant are ABSOLUTELY still available. I got a new tube of the orange stuff last year for my M119 Top-End Refresh. The clear stuff should also be available.

Many mechanics use RTV or other sealants. I recommend using what MB specifies -- especially the orange anaerobic sealant. I believe that it is made by Loctite, and it is avaialble on the aftermarket via Amazon and other sources if you don't want to get it from MB. A good forum search along the lines of "orange anaerobic sealant Loctite" will give you the proper Loctite product number. If I remember correctly, it may be called Loctite 5900 or something? HOW-TO: M104 / W124 Top-End Rebuild | "HOW-TO" Tutorial Articles

Thanks Gerry. I’m a bit of a MB purist who is greatly misunderstood and wrongly mislabeled as a perfectionist. I will try my local dealership in Wilmington NC and also do the research on the TDS for Loctite. By the way, I’m enjoying every minute reading your write-up on the top rebuild.
Greatly appreciated

 

[gsxr]

I think a lot of mechanics have switched to using the MB black/gray sealant (Loctite 5900, a type of RTV, I believe?) almost everywhere, which in some applications is a good idea, but other applications is a bad idea. RTV will "glue" two parts together, while the orange anaerobic does not.

I *think* you can safely use the black/gray 5900 (003-989-98-20-10) in place of clear RTV, but I would not use anywhere the orange anaerobic is specified.

 

[Seangbadee]

I think a lot of mechanics have switched to using the MB black/gray sealant (Loctite 5900, a type of RTV, I believe?) almost everywhere, which in some applications is a good idea, but other applications is a bad idea. RTV will "glue" two parts together, while the orange anaerobic does not.

I *think* you can safely use the black/gray 5900 (003-989-98-20-10) in place of clear RTV, but I would not use anywhere the orange anaerobic is specified.

Thanks Dave

 

[Seangbadee]

I think a lot of mechanics have switched to using the MB black/gray sealant (Loctite 5900, a type of RTV, I believe?) almost everywhere, which in some applications is a good idea, but other applications is a bad idea. RTV will "glue" two parts together, while the orange anaerobic does not.

I *think* you can safely use the black/gray 5900 (003-989-98-20-10) in place of clear RTV, but I would not use anywhere the orange anaerobic is specified.

Wow, I’ve been given the run around from Naperville to Alabama. 002-989-47-20-10 [orange anaerobic] is NLA. Actually there is one in SC, and one in VA (MB Charlottesville) but they do not ship to customers due to Hazmat regulations, and do not accept credit cards from out-of-state addresses! I asked Dick Dyer to do a dealer to dealer sale and they refused. The interesting thing is that 001-989-89-20-10 [orange anaerobic] is still available (plenty in the Fort Worth warehouse), and this is what mboem is going to ship to me.

I will get 002-989-45-20 [clear RTV] from rmeuropean.

 

[Seangbadee]

Wow, I’ve been given the run around from Naperville to Alabama. 002-989-47-20-10 [orange anaerobic] is NLA. Actually there is one in SC, and one in VA (MB Charlottesville) but they do not ship to customers due to Hazmat regulations, and do not accept credit cards from out-of-state addresses! I asked Dick Dyer to do a dealer to dealer sale and they refused. The interesting thing is that 001-989-89-20-10 [orange anaerobic] is still available (plenty in the Fort Worth warehouse), and this is what mboem is going to ship to me.

I will get 002-989-45-20 [clear RTV] from rmeuropean.

Thanks for the edits

 

[Seangbadee]

Wow, I’ve been given the run around from Naperville to Alabama. 002-989-47-20-10 [orange anaerobic] is NLA. Actually there is one in SC, and one in VA (MB Charlottesville) but they do not ship to customers due to Hazmat regulations, and do not accept credit cards from out-of-state addresses! I asked Dick Dyer to do a dealer to dealer sale and they refused. The interesting thing is that 001-989-89-20-10 [orange anaerobic] is still available (plenty in the Fort Worth warehouse), and this is what mboem is going to ship to me.

I will get 002-989-45-20 [clear RTV] from rmeuropean.

My anaerobic sealant finally arrived. Part number 001-989-89-20-10

 

[gsxr]

Nice! Ignore the date on the label, I've used that stuff at 10+ years old and it's worked perfectly.

It's the MB gray sealant (Loctite 5900) that refuses to set up when it expires, and it has a short shelf life... you didn't buy that AFAIK so it's not an issue.

 

[Seangbadee]

Nice! Ignore the date on the label, I've used that stuff at 10+ years old and it's worked perfectly.

It's the MB gray sealant (Loctite 5900) that refuses to set up when it expires, and it has a short shelf life... you didn't buy that AFAIK so it's not an issue.

You already answered my question even before I could ask it

 

[gerryvz]

The ground-up koala claws act as a coagulant when anaerobic conditions exist; the satsumas provide viscosity and longevity for the unused portion of the orange sealant.

 

[Seangbadee]

Re: M104 / W124 Top-End Rebuild

Today I did a follow-on job to the top-end rebuild -- adding the bottom connector for the front plastic cover of the cylinder head. This piece was missing on my engine when I took it apart, and I only noticed that it was there via the EPC diagram. So I threw this rather cheap part on my next parts order, and installed it today.

I also compared the cover for the upper wiring harness to the original one, which has a broken tab. Again not anything that is a problem, but one tab of the cover doesn't grip the harness cover, so I thought I'd replace this $16 part. Unfortunately, the EPC is WRONG and the part I ordered is for a later M104.992 engine, yet when I cross-referenced it with my engine number (and just did so again tonight) it said that this later cover was the correct one for my car. Since it's only $16 I'm not going to bother returning it, so I'll probably put it on eBay or sell it to someone who has a mid to late 1995 E320 wagon or perhaps a 1996 car, if applicable.

I did a compare of the yellow sticker that came on the new harness cover (a 210 part number) with the older 124 (original E320) and 123 stickers, both of which are considerably/noticeably larger.


First off, here are a couple of views of the small grommet, along with the hole in the end of the timing cover where it presses into:
View attachment 23356 View attachment 23357 View attachment 23358


You can see how it slip-fits into the bottom of the front engine cover, keeping the bottom of the cover secure and away from the serpentine belt, which is very close by.
View attachment 23359 View attachment 23360


Here you see me using my small hooked tool to explore the inside of the hole in the end of the timing cover, to ensure that it isn't blocked by crud and that the entire length of the grommet can be pressed inside of it.
View attachment 23361 View attachment 23362 View attachment 23363


Then you see me holding the grommet into position, while I use a long screwdriver against the end of the fan to lever against, to press it into the end of the timing cover. The third photo shows the grommet all in place.
View attachment 23364 View attachment 23365 View attachment 23366


And here's the final result. Identical to how the cover fit BEFORE the grommet was installed, but now it is 100% factory correct
View attachment 23367



Here are some comparisons of the old and new wiring harness covers, along with a photo comparing the old 123 yellow sticker to the current 210 sticker. Quite a difference. I decided not to bother fitting the wiring harness cover - my cover is just fine, though I'm angry about the error in the EPC.
View attachment 23368 View attachment 23369 View attachment 23370 View attachment 23371 View attachment 23372 View attachment 23373 View attachment 23374 View attachment 23375 View attachment 23376 View attachment 23377 View attachment 23378

Gerry,
What’s the part number for the little tab? Seeing this article just reminded me that I need one.
Cheers.

 

[Seangbadee]

Re: M104 / W124 Top-End Rebuild

At this point, I was deciding to begin to wind down for the night, and to do some relatively light "housekeeping" tasks.

So, first off I sat down on the garage floor and proceeded to separate the injectors from the fuel rail. I bagged each of the injectors and marked which cylinder they had come from. I have decided to send the injectors in to have them sonically cleaned and restored, and flow tested before and after.

This is all just part of "doing the rebuild right" instead of slap-dashing things back together. Hopefully the injectors, with 200K miles on them, are in good shape and can be reconditioned to provide some increase in power and efficiency through better atomisation of the fuel.

Here you see me using a flat-blade screwdriver to gently coax each injector out of the fuel rail.
View attachment 20937 View attachment 20938


And then, you see my small "pick" tool removing each of the fuel injector o-rings. These will be replaced and are on order.
View attachment 20939 View attachment 20940


The last job for the night, was to remove the ETA from its resting spot on the lower part of the intake manifold. This was accomplished by removing the four 5mm Allen bolts that held the ETA to the manifold. They weren't very tight, so this was a rather easy job.
View attachment 20941


Then, I removed the two 10mm nuts that held the plastic ETA connector in a static position. Then I flipped up the security flap that securely holds the two halves of the ETA plug together, and then pulled the two halves of the ETA electrical connection apart. This only took a couple of minutes.
View attachment 20942 View attachment 20943 View attachment 20944 View attachment 20945


I next removed the spring and ball-socket connector that connects the throttle linkage to the ETA. After doing that, the ETA was able to be lifted out of the car, and placed on the garage floor for further inspection.
View attachment 20946 View attachment 20947 View attachment 20948 View attachment 20949 View attachment 20950


Here's a view of the top of the lower intake manifold, with the ETA removed.
View attachment 20951


My last task for the night was to examine one of the fossilized hoses coming down from the top half of the intake manifold, and to check its part number. Both of these fossilized hoses are on my first parts order, so they will arrive soon. I can't explain enough how fossilized these hoses were. They were actually plastic, not rubber. Hard to believe they once WERE rubber.
View attachment 20952


And that does it for the night.

For Sunday's tasks, I will disassemble the remainder of the intake manifold and remove it and associated items from the engine. Then I will delve into removing the valve cover, and disassembling the cylinder head itself by removing the camshafts. The head will be prepped for delivery to the machine shop (I hope to deliver it to the machine shop by Thursday or Friday of next week).

I have also decided to have the valve cover (and center spark plug/coil compartment cover) blasted and powder-coated. I have the time, and it won't be that expensive to have this done. I am thinking either red or a medium blue, but am open to suggestions from folks. A red valve cover would give the engine compartment some visual pop, eh?

Give me your thoughts on this.....

Cheers,
Gerry

Gerry:
What media was your cover sand blasted with? My cover is showing flaking with some gray deterioration and I’m thinking of getting a used cover to replace it. Any thoughts on this?

 

[Seangbadee]

Gerry,
What’s the part number for the little tab? Seeing this article just reminded me that I need one.
Cheers.

I found the part number. It’s 104-016-03-38 and it’s listed as a screw. It is the retainer for the M104 front cover.

BRACKET A 1040160338 - EGG Mall

Benz,A 1040160338,S2838817,BRACKET,BRACKET A 1040160338

www.eggmalltech.com

Screw 104-016-03-38 | MB OEM Parts

104-016-03-38 - Screw

www.mboemparts.com

 

[Seangbadee]

Re: M104 / W124 Top-End Rebuild

There is a HOW-TO on the oil pressure sender on the M119 here. It's the identical part to the M104.


A very large chunk of my time spent was photographing and documenting in my notebook the work done, step by step. I would say this would have been a total of 10 hours of the total time, probably close to an hour a night just spent on taking photographs and writing/drawing in my shop notebook. I believe in total that I took well over 700 photographs.


The upper timing cover reseal is not that difficult of a job. For the record when you do it, you MUST pre-insert the lower left bolt into the cover BEFORE you re-install it, as it is impossible to insert the bolt into the cover after it is mounted because the long bolt cannot clear the smog pump pulley.

It is also important to add the center o-ring seal to the rear of the timing cover, at the time you replace the cover back onto the end of the cylinder head. This ring comes with the MB head gasket kit. It's easy to forget these two items.

Lastly, one common mistake is that people insert the metal pin that goes through the upper left (driver's side) timing chain rail BEFORE they install the timing cover. It is EXTREMELY difficult to replace the timing cover when this timing chain pin is in place, because it provides an additional item that must be fit "straight on" into its hole in the timing cover before the cover is pressed backward over the green "C" seal and into place. This often causes the seal to be "rolled" and thus not form a good seal. So the strong advice here is to only press in the timing chain rail pin AFTER the timing cover is pressed and bolted into place.

Cheers,
Gerry

Thank you Gerry.

 

[Duh_Vinci]

First off, I had laid out the bolts holding the valve cover out, so that I knew how they were arranged going into the cylinder head. The metal/rubber washers will be replaced as part of the reassembly process - they have been ordered from MB. They are a very important part that prevents oil seepage/leakage at the valve cover bolts.

Gerry, I assume these sleeves are 104-992-18-20 ? I was planning on doing valve cover on my brother's SL320, but the dealership said these parts NLA, permanently discontinued. Is there an alternative? Can just the rubber part be replaced with another, similar well suited part?

Regards,
D

EDIT, there seem to be an alternative part listed (maybe?) according to this diagram M 104.991 - CYLINDER HEAD COVER > Mercedes EPC Online > nemigaparts.com Number 80, in one spot listed as 104-992-19-20 but I can't find definitive answer if these are interchangeable or not

 

[geraniumtr]

Duh Vinci, I'm not Gerry but I did this job on my E320 (M104.992) last summer . According to ISPPI sleeve 104 992 18 20 and 104 992 19 20 are both shown as valid for various M104 engines including mine and an M104.991. They are both superseded from older part numbers. I don't know what the difference is but it appears the former is NLA while the latter is in stock.

Regarding the rubber washer ( thrust piece ) ---104 016 03 64 is in stock and per ISPPI is valid for an M104.991 engine.

By the way I found my old valve cover gasket to be in good shape; still pliable and soft while the rubber washers were hard as a rock.


Regards,

Peter Weissman

 

[Duh_Vinci]

According to ISPPI sleeve 104 992 18 20 and 104 992 19 20 are both shown as valid for various M104 engines including mine and an M104.991. They are both superseded from older part numbers. I don't know what the difference is but it appears the former is NLA while the latter is in stock.

Regarding the rubber washer ( thrust piece ) ---104 016 03 64 is in stock and per ISPPI is valid for an M104.991 engine.

By the way I found my old valve cover gasket to be in good shape; still pliable and soft while the rubber washers were hard as a rock.


Regards,

Peter Weissman

Cheers Peter!

I believe I now understand, as I'm looking at the canceled order from the local dealership my brother just brought me.

8x 104 992 18 20 (NLA)
4x 104 992 19 20

And from Gerry's pic, I just realized that the length is different



So the long ones are NLA (8 needed).

Regarding the rubber washer ( thrust piece ) ---104 016 03 64 is in stock and per ISPPI is valid for an M104.991 engine.

As to the rubber washer (thrust piece) 104 016 03 64 is this the one pointed to with the arrow? If that's the case, these seem to be available, just checked via classic mb site, meta_title

Already purchased all the factory gaskets otherwise. His (my previously) car has 2 of the spark plug rubber seals sipping a little, found out recently after changing his plugs, little oil on the threads, hence we want to do the gasket.



Regards,
D

 

[geraniumtr]

Yes of course that’s correct… different lengths. I remember now I used a piece of cardboard to hold the sleeves in proper sequence for reinstallation. Question for you— why replace these sleeves? They’re just a metal tube that don’t deteriorate. I just cleaned mine up.

The highlighted part in your photo are the rubber seals. There are also 2 rubber semi circle pieces that fit on the rear of the engine. Don’t have part number at this moment but can find it.

Regards,

Peter

 

[gerryvz]

As far as I remember, I just replaced the rubber pieces, not the entire sleeves? I'd have to go back and look at the entry. Man, I think I did that M104 job back in what, 2013 or 2014?

I really need to pull my G-wagen's M104 and do that thing inside and out, just for shits and giggles. It's got 130K miles on it, though someone has been in there before because I can see RTV squeezed out of the valve cover gasket area. Dunno if the head gasket was ever replaced, but 130K is just about on the money for original M104 HGs to be replaced.

 

[Duh_Vinci]

... Question for you— why replace these sleeves? They’re just a metal tube that don’t deteriorate. I just cleaned mine up.

The highlighted part in your photo are the rubber seals. There are also 2 rubber semi circle pieces that fit on the rear of the engine. Don’t have part number at this moment but can find it.

Not sure why, to be hones, I guess I was thinking those pieces are all inclusive, sold as one...? Those rubber half circles, have the, came as part of MB gasket kit, appreciate it!

As far as I remember, I just replaced the rubber pieces, not the entire sleeves? I'd have to go back and look at the entry. Man, I think I did that M104 job back in what, 2013 or 2014?

Gerry, as Peter mentioned, if the sleeves are metal, you probably had replaced just the seals (but only you would know Great thread. very helpful!

Regards,
D

 

[gerryvz]

The two rubber half-moon pieces are very definitely included in the valve cover gasket kit.

It’s imperative (and can be difficult given their location in the rear) to get them placed 100% properly to avoid oil leaks.

 

[M104-AMG]

Re: M104 / W124 Top-End Rebuild

<SNIP>

At this point, I made a crucial mistake, and I should have known better. I pulled the manifold straight up and out, and didn't disconnect the two vacuum hoses that attach directly to the underside of the manifold. Unfortunately, both of the hoses had become fossilized (never seen rubber hoses this hard ... EVER) and fused to the plastic connectors that they clamped to. I am talking FUSED....as in inseparable. Impossible to tell where the plastic ended and the rubber hose began. So I completely cracked one of the fittings off, and broke the end off the other one. Stupid mistake. I will have to tap two new fittings into the plastic housing. Not the end of the world, and I have plenty of time (weeks) until I remount the intake manifold top half, but I am PISSED at myself for doing this and not knowing better. UGH.

Here are a few photos of the removal of the top half of the intake, and the carnage that I described above per the two vacuum hoses.
View attachment 20927 View attachment 20928 View attachment 20929
<SNIP>


Continued in next post....

Gerry - any tips on tapping the plastic and what size nipple did you use ?

TIA,
neil

 

[gerryvz]

Gerry - any tips on tapping the plastic and what size nipple did you use ?

TIA,
neil

I didn’t end up tapping the plastic. I ended up buying a used manifold and carefully removing that entire plastic piece and gluing it to the old manifold.

It’s all detailed and illustrated in the HOW-TO.

It was much better to replace the entire plastic piece (not available separately) than to try to tap a broken piece of plastic. Judgement call but the correct path. Fortunately at the time spare M104s we’re fairly common in the Houston wrecking yards.

 

[willard]

This is the best M104 thread EVER! kudos!
I have 1994 (MY95) SL320 EU too and love that underrated engine

 

[gerryvz]

This is the best M104 thread EVER! kudos!
I have 1994 (MY95) SL320 EU too and love that underrated engine

Appreciate the compliment.

My M104 in my 1995 G-wagen has an increasingly leaking front timing cover, so I'm adding a re-do of this to my list. The engine only has 130+K miles on it, and it appears that it has already been re-sealed at least once.

Fortunately in the G-wagen engine compartment, there is MUCH MUCH MUCH more room to work on the engine. I won't even have to jack the truck up to get at the bottom side of things.....

 

[anderzen]

Hello All,

I took off my C36's valve cover yesterday in hopes to drop it off for powder coating... discover baffles inside that look like they are held down by #2 philips screws. Tried to remove but they didn't budge and didn't want to strip them. Anyone familiar on removing these baffles or is that mentioned in any part of this thread? Thank you!

 

[gerryvz]

I removed my M104's baffles (perhaps there are photos of it) with little to no issue. Perhaps soak the screws in Kroil overnight.

They can powder coat the valve cover with no problem with the baffles on there, though.

Note that the valve cover is likely magnesium, which any good powder coater will warn you may not take well to powder coating, because magnesium tends to "out-gas" and cause adhesion issues and/or bubbles under the powder coat. I've had a couple done and never had an issue, but it's something that can happen. I have had two powder coaters, in Texas and here in Maryland, tell me this totally independently. Again, that said in both cases the product I got back was just fine and I never saw any issues with it.

 

[gerryvz]

Anyone familiar on removing these baffles or is that mentioned in any part of this thread?

And by the way, yes this is mentioned / illustrated here in this thread.

And another one here too.

Search term: "valve cover baffle" using "advanced search" button.


Why in the fuck do I keep creating these HOW-TOs when NOBODY ever takes the time to actually read through them and absorb / remember what is discussed. Generally I try to make the HOW-TOs pretty damn complete and illustrate them photographically as much as I can.

All to naught, I guess. People just too quick to hit the "new thread" button (ignoring our great forum search capability) and/or ask a redundant question IN THE VERY SAME THREAD WHERE THE QUESTION IS ANSWERED.

 

[nocfn]

The human condition Honch!