Mercedes Timing Chains. - M.M
I wonder if anyone (Aprilia?) has good experience of Mercedes timing chains, at the moment I'm thinking about an early W124 E-class with a 2.0 engine that only has the single row chain.

It has the "classic" rattle for just a couple of seconds after startup which I think is the chain slapping about prior to the tensioner fully tensioning.

Taking advice there seems to be a fair difference in the repairs folks would do.

Some say the tensioner unscrews from the side of the block and changing this will efect a cure.

Others say do the tensioner and chain, their method being to cut the chain with an angle grinder over the cam pulley and join the new chain to old so it can be pulled through without removing the timing case.

Finally I've been told both the above are skimping and you should remove the timing case and replace the chain, tensioner and sprockets as a kit...also looking carefully at the tensioner "slipper".

This vehicle ought to have another ten years life so any repair needs to be more than a quick fix.

Thanks,

M.M
Mercedes Timing Chains. - Aprilia
If it is single-row then you are looking at an '88 or earlier car. These last about 100k mi. per chain.

The only lasting solution is new sprockets and chain; there are six parts: chain (get OE), tensioner, D-rail, cam gear, intermediate gear and crank gear. The whole lot from ECP will be a bit under £100. Should last you another 100k.

A quick 'bodge' would be to cut the chain as you describe and feed another one through, then swap the tensioner. Chain and tensioner are about £15 each.
Mercedes Timing Chains. - M.M
Many thanks Aprilia.

Yes it is a very early car, 1986.

I was inclined to advise/price the full job so your info rather confirms this.

What about the tensioner issue, is it as simple as it not holding oil pressure overnight so it allows the chain to thrash on startup...and if so is there ever an intermediate solution of changing the tensioner well before the chain is worn?

M.M
Mercedes Timing Chains. - Aprilia
As the chain stretches and the sprockets wear a bit then a lot of 'slop' builds up in the system. It takes longer for the tensioner to take this up - factor in a tensioner that doesn't hold oil and you get the problem.

I guess the issues are:

1. Might the chain fail - well, yes, in rare instances they do.
2. What about the penalty in terms of mis-timing? (i.e., as the chain stretches the cam timing is increasingly in error).

Personally, for what it costs, I wouldn't bother with intermediate solutions.

One engine where you have to be really careful is the 4.2 V8 (used on the W126 S-class,.e.g. 420SE, amongst others) - the chains on those do sometimes 'let go' and wreck the engine. You have to replace those as soon as you hear a rattle.
Mercedes Timing Chains. - RichardW
MM,

Timing chains and angle grinders in the same sentance????

Have you been having too much falling down water?


RichardW

Is it illogical? It must be Citroen....
Mercedes Timing Chains. - M.M
I know I know...but it appears quite a few folks follow this method and that is how Haynes details it!!

....Remove valve cover to expose camshaft sprocket, stuff rags about the place, grind down one of the chain links until it will come off, join the new chain to the old, turn the engine over holding both chains so the old pulls the new one through, join the new chain at the top with the link, use a hammer and block behind the cam sprocket to peen over new link pin in-situ...

Yes really!!

Rest assured I'm basing advice/cost on doing the full job.

M.M
Mercedes Timing Chains. - Dynamic Dave
M.M,

I once had to change a cam chain on an old Honda CB500 DOHC motorbike engine. Surprise surprise, Haynes also suggested this method as well.

 

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