Hello out there!

I have a 1990 420 SEL and it is making a tapping noise like a stuck lifter. I had a mechanic take the valve cover off and he said it wasn't anything in the valve train. All lifters were working, and there were no broken rocker arms. I don't think he really knew Mercedes. So I took it to another certified Mercedes Mechanic and just listening to the car he said it might be a shim problem or a valve may be out of adjustment. I'm taking it back to have it investigated further next week. It's a very solid knocking sound but definately not rod knock. Does this sound familiar to anyone?

thanks

If you have the M119 engine then it is likely the oil tubes, common issue (and symptom) with that engine.

http://www.k6jrf.com/MB_lifter.html

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1993 190E 2.3
2001 SLK230
1971 LS5 (454) Corvette Convertible

Hi SLk230 Red!

I'm an old backyard mechanic I owned Chevelles etc. Is this something I should be able to handle or is this a garage only thing ie. special tools etc. Also, how can I be sure that this is the problem?

Finally, if it is a garage only fix, how much am I looking at...ball park?

Thanks

You've got the M116/117 engine, not the M119. Have a tech with MB experience remove the rocker arms and inspect them closely, as well as the cam lobes. If there's no measurable wear, make sure the compensating elements (lifters) are torqued properly. If they loosen up even a little, the oil pressure can't build up and you'll get a valve tap.