PeachParts Mercedes-Benz Forum - View Single Post

mpolli · #15 05-27-2017, 03:45 PM

So I want to close out this thread and hopefully help anyone who ever has this issue or tries this repair.

To recap:

Symptom I had: A noise at idle (750 RPM) that was under the front of the cam cover of the engine (where the timing chain is) and occurred around once per second.

I decided (correctly) that the only thing that repeats at that speed at idle is the complete rotation of the timing chain. In fact, the actual repetition rate would be (RPM/60)/(chain teeth/crank sprocket teeth) = (750/60)/(128/16) = 1.56Hz, fairly close to my estimate of 1Hz.

I guessed that there was a defect in the chain caused by wear and it could be in danger of snapping.

It turns out it did in fact have a stiff or seized link that was caused by wear (see picture)

So I tried the procedure mentioned previously and had pretty bad results. I am thinking I was supposed to have one of these:

BGS Tools Timing Chain Mounting Tool For Mercedes M111 8680 | eBay

Even though the Mercedes procedure does not mention it. Alternately if I had to do it again I might try leaving the camshafts unengaged from the chain and just winding the chain through and around the crank. As long as none of the valves are open this might work.

The other horrible thing the Germans did is the chain tensioner. I have no idea what the official way is to get the cap of that screwed on while simultaneously compressing that big spring that is in it. I only found one video on YouTube where a guy actually did it and he did not film what he actually did, but he said it took an hour and was "soul crushing". Those are strong words but I think fair in this case.

This job far exceeded my expectations of the amount of time and work involved.