Dune

II put a used engine put in my 2005 C230 last May due to the timing chain jumping at 103K. I have only put about 3K miles on it since May, but recently I started hearing a mechanical fluttering sound (sounds like knocking) in what seems to be the top of the engine.

The sound only occurs between 2000-3500 RPM, if you hold the accelerator down in that range you can hear the "fluttering". If you quickly rev the engine above 3500 RPM, you will hear the sound as it passes through the 2000-3500 RPM range and again when the engine decelerates back through that RPM band. At idle it does not make the fluttering or knocking sound. It sounds mechanical like it is in the engine drive train, like a cam/lifter issue, but my experience is if it was the drive train the sound would be persistent. As such, without my suggestion, my mechanic changed the cams, the timing chain and tensioner thinking this would solve the problem. The same sound is still there in the same RPM range. the engine is not missing or shaking like it is a timing issue. No engine light. It idles and accelerates perfectly.

I am lost now, could it be the water pump bearings, supercharger, something external to the engine? I have no idea where to go next.

Glyn M Ruck

Remove the Poly V belt & see if the noise goes away. That will soon tell you if it is an accessory.

Dune

Simply remove the belt and start the car? Ok to rev and run for a few minutes in that manner?

Glyn M Ruck

Yes - Watch the temperature. Don't let it overheat.

Dune

Glyn thanks for the advise, I had my mobile MB tech come over and take look at the car since the show who swapped the engine could not diagnose the problem.

We have determined the sound is for sure in the timing chain area of the engine. It was suggested that the timing chain guides may be the culprit. Does this sound like it could be possible, is it possible to incorrectly install the timing chain guides....?

Glyn M Ruck

Possible or they are damaged. Maybe the tensioner was not set correctly either.

Dune

Is there a specific procedure to setting the tensioner?

What is involved in replacing the guides and or the tensioner?

Glyn M Ruck

Take a look at Hogger's excellent thread in this regard. He did the whole job himself.

Dune

Glyn, forgive me. Hogger's? Not familiar, is this a poster I should search for?

Glyn M Ruck

Yes ~ look up Hogger. He DIY'ed the whole job very well.

Glyn M Ruck

Here:

https://mbworld.org/forums/c-class-w...ine-apart.html

Dune

Is this pin supposed to be in more, it is up against the housing. This could be the knocking sound I am hearing.

If so, I know I access through the front....how do I screw it back in?

Dune

Does this pin need to be in more? It is up against the housing, I am thinking this is the noise I am hearing.