RE: M-117 V-8 engines (either aluminum or iron)

I’ve searched the archives, but I can’t find anything on a way to isolate a single noisy/leaking hydraulic lifter/compensating element. Any suggestions or methods would really be appreciated. Thanks in advance for your help!

Well can you isolate it to one side or the other. If you can, then you have narrowed your choices to 8 possiblilties. Try using a long piece of metal rod on the valve cover and the other end pressed near the front of your ear. Better yet, either borrow or buy a mechanics stethoscope and use that to try and locate the offending parts.

I do not know if this can be done on a Mercedes but on the other cars that I have been working it is done as follows: The valve cover is removed and the engine starts and idles (with the valve cover still removed). Then, get a .020 inch feeler gage and slip it between each valve tip and rocker arm. When you get to the one with the bad lifter the noise should change markedly.
Now I am not sure if it can be done in a Mercedes but all the cars I have been working on (primarily domestic V8) that is how we do it. Hits the target every time.

I have found a stethascope is the best solution for this problem. I use mine for alot of diagnosis (vacuum leaks,noisy belts ect...)I think every good mechanic should have one. Good luck.