I have a 1988 300E and I am about to take it in for its 105000 service. It's starting to leak oil badly from its Timing Chain cover. At its last service I was advised that the gasket should be redone for $300. The mechanic (MB Dealer) also told me that it is recommended to replace the timing chain at 100,000 miles for $1100 is this true? I'm thinking of just doing the cover gasket and leaving the chain alone if there isn't much slap. Is this advisable or am I just being too tight. Does MB really recommend changing the chain at 100,000 miles or is the dealer trying to milk me? Additionally I'm thinking of switching over to Mobil 1 and going the full 7500 miles between oil services, instead of 3,250(outside Chicago) with Dyno oil. Has anybody done this and did you have gaskets start leaking ? Thanks, Dino

Just to clarify, they want 1100 for both the timing chain and the gasket

Search the archives for instructions on checking the degrees of stretch to see if it is time to replace the chain. 100k is a good estimate on when to change the chain, tensioner, and guide rails on most models.

Edit: oops, just saw your clarification -- that price is probably OK.

Yes, thin synthetic oil will slip past aged gaskets on an older engine. Hope this helps, Andrew Seidel.

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86 560SEC
85 500SEC Lorinser
83 300D Turbo
75 240D

I've been running 5w30 and 10w40 in it since new. Would I still have a problem since I was reading on Mobil's web site that I shouldn't.

Just looking for real-world results.
Dino

Not to start another debate, my opinion is that 99% of it is changing the oil and filter with the correct frequency. Playing with different brands and weights to get that remaining 1% is up to your wallet and yields little gain on an older car. Bracing myself for another debate , Andrew Seidel.

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86 560SEC
85 500SEC Lorinser
83 300D Turbo
75 240D

While there's no harm in replacing the timing chain, the general comments from techs in this forum is that M103 timing chains don't fail if treated to frequent oil changes. There are very few incidences of M103 timing chain failure in the archives, and then it's usually caused by a foreign item. The ratcheting tensioner when working ensures that there isn't any slap.

Checking chain stretch is a primarily Diesel thing. The ratcheting tensioner makes such a test on a M103 not very meaningful... or so I understand.

If you're removing the timing chain cover to replace the gaskets then by all means replace the chain and guides and maybe even the tensioner.

If you can do the timing chain cover gaskets yourself you might as well do the head gasket as well. Same level of difficulty.

If your engine leaks now, it will continue to leak with Mobil 1. It shouldn't leak with Mobil 1 after you replace the head and timing chain cover gaskets.

Sixto
91 300SE
81 300SD

As previous respondents have noted, this is certainly one of the most hardy timing chain systems of the Benz engines, mostly due to the ratcheting tensioner.

That said, even if you did want to replace the chain, there is some sort of misunderstanding on the chain replacement price. If they will remove the lower timing cover for $300, the difference to replace the chain is insane. If they have it down that far, changing the chain would just be a few extra minutes of work, and that chain is relatively inexpensive.

You need to get a clarification on this.

Good luck,

I've had timing chain cover leak fixed at around 85K, so I didn't worry about the other internals.

Car is over 110K now, but I still have no worries regarding timing chain, but I also am religious about the oil changes.

No head gasket issues yet (knock on aluminum alloy), but when it does happen, I will get the chain serviced as well as other items when the head is removed.

If you want piece of mind though, go ahead and do both the chain and gasket now, so no worries for another 100K or so...

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