M103 timing chain and upper cover - PeachParts Mercedes-Benz Forum

Amuso · #1 07-01-2002, 11:22 AM

I've been reading a lot of posts on this here. Got me a bit confused on wheter to change the chain or not. From what I've learned it seems that it is not necessary to replace it until it starts making noises on start-up, and not before 150k miles. Does this sound good?

What does a worn chain sound like? Can someone explain how to check for it and the sound it makes? And would it only show up when cold-starting, or always?

I have a small leak making a little puddle from the front of the engine. From what I found out this could be due to a leaking upper chain cover. The seal is cheap so I am considering replacing it. Someone mentioned a special paste/sealant to use on this to make it seal well. Anybody got a partnumber to order from Fastlane? And some instructions to go along on how to do this would be nice too.

I tried to find the timing chain replacment document on the W124 CD-ROM from MBUSA, but failed. Can anybody give me the correct document number? I had no problem finding it for my W126 though (05-1xx something in that case - can't find any 05-docs for the W124 though).

Thanks for any input!

pmizell · #2 07-01-2002, 11:30 AM

..replacing the timing chain is NOT an easy task. It is highly unlikely that you need to replace your chain; many techs on this board have stated they have never seen an M103 chain break, and when they did it was due to castostrophic failure of the chain guide itself.

I DO recommend replacing the chain tensioner guide and the chain rail if it has never been done before.

The sealant you need is Loctite 5900. I don't have a p/n but phone Phil at Fastlane and he'll fix you up.

Good luck!

~Paul

_________________
'91 300E, 213K miles

suginami · #3 07-01-2002, 12:42 PM

I'm not a technician, but I see this question come up from time to time.

I've noticed that because the techs recommend timing chain and rail guide replacement on the V8's every 100-120,000 miles, or so, that everybody naturally assumes it is also recommended on the inline 6's, as well.

But everytime this question comes up, the answer is always the same. Timing chain replacement on M103's and M104's is not needed. They never do it. The chains are very short and don't stretch like on the V8's.

Do a search and you'll see what I mean.

jay123 · #4 07-01-2002, 05:09 PM

I agree. The first thing to go is the chain guide and/or the chain tensioner. Sometimes a bad tensioner will cause the chain to slap around. As long as proper maintenance and good oil have been used on the car, don't worry about the chain.
I bought my wife a '90 190E 2.6 w/160k on the clock. Changed the top timing cover seal and the little bottom one, plugs, and valve cover. No chain slapping or funny noises. The car runs great. Good power and pep. I'm planning on adding an air filter intake modification similar to 2Phast.com. My only regret is that I wish it was a stick. They are not that easy to find. But all around, the car is GREAT !!

John Plut · #5 07-01-2002, 10:51 PM

I too had a timing chain cover leak in my '88 260e with 130,000 miles and wondered if I should replace the chain. I decided to do a very careful inspection of the chain rollers, links and pins with the cover off and could not detect any wear at all so I didn't change it.

The timing cover seal replacement is not difficult but involves removal of the fan and serpentine belt. You will need a new camshaft seal (for the distributor drive) in addition to the timing cover seal strip and the special sealant. I ordered the locktite 5900 and it came in a MB tube with a MB part number. One of the keys to stopping the leak to to remove all the old sealant and make sure the sealing surfaces are clean and dry. I used a thin pick to scrape the crevices and corners out. My engine is now bone dry after putting up with drips for years.

#6 07-02-2002, 09:29 AM

Hi,

I have my car apart as we speak doing the same fix.

I was able to remove all necessary parts with the belt still in place. Did remove the fan shrowd, distributor and valve cover.

I had to remove a coolant return pipe, which had a small bolt holding it down under the distributor, took me a few minutes to figure that one out.

I will do tune up when reasembling, wires, rotor, cap, plugs, etc. I will also need to get a new o-ring seal for water return pipe.

Not a tough job though, and a for the chain, looks new, real thick and does not apear to need servicing.

From past experience I have found timing chains to be super durable, as long as you regularly change oil and filter.

Good luck,
Joel

Amuso · #7 07-02-2002, 10:27 AM

Thanks for the input everyone! I'll sleep better at night now

It doesn't make any funny noises that I've noticed.

I ordered the U-seal to replace at a later time. It drips a little bit from the front, over at the passenger side from the top area. Going to get a valve cover gasket too.

Since I'll be replacing the A/C clutch coil I will do a full seal fix at the same time. Would appriciate it if Joel, John or somebody else could provide a list of the necessary seals/gaskets to do while in there.