Ok, so I just picked up an '85 190d about two weeks ago. I have some questions regarding the timing chain. I can hear the chain making a slight clattering noise when the car is at idle, but as soon as rpms go up, it quiets down. I have not had the valve cover off to check it yet, as I didn't know if the noise was normal or not ( I've never heard another one so i don't have a comparison). The car has 230k on it, with no service history.

If the chain does need to be replaced, how bad of a job is it? What am I looking at as far as other things that I should replace while I'm in there? I'm guessing it's going to be about 16 hours of work to complete the job from what I've read about the OM 602 and 603s (I've been searching this topic and can not seem to find too much about the OM 601 engine)

Thanks a bunch!

With the engine running take a wooden dowel or a length of 1" x1" limber and position that on the belt tensioner, on the side with the shock, left hand side looking at the engine from the front. Push downward on the tensioner, if the sound you think is the timing chain lessens or significantly changes its likely that the sound you hear is a loose bushing in the tensioner's shock. These engines will often produce all kinds of noises from that area when this happens.

I'll give that a try when I get to work tomorrow and post the results. I'm almost certain it's the chain though. It's a consistent noise, and it's the loudest when listening through a screwdriver at the valve cover bolts.

Also I might add, it gets slightly quieter when warmed up.

2x Billy bob.... Mine bad chain was also a worn out bushing in the tensioner shock

You guys are giving me some hope! It would make sense that I'm hearing the noise at the top of the cover for the belt dampener as it would travel upwards that way. I'll let you know my findings in the morning.

P.S. This board is amazing!!!

So I pulled into the garage this morning, put some pressure on that tensioner and the noise went away!!! Here I was certian that it was a timing chain. Thank you BillyBob! I can sleep a little better at night now. Within the first few thousand I put on it I will check the wear pattern of the sprocket and for chain streach just to have some peace of mind.

Is that bushing seperate from the tensioner itself? I heard some people say that the tensioner itself is prone to failure, so is it a preventive maintence item that I should just do?

I also have a fluctuating oil pressure gauge when it's at about 2 bar, in past expeariances it's just been a sticky sender, I'm guessing the same with this? Or should I be looking towards cluster grounds or gauge issues? I'm pretty sure I don't have lubrication issues as the engine is nice and quiet aside from the dampner bushing.

I think that's it for this morning, I'm sure I'll think of some more questions later. Thanks again!!!

There are three wear components in the belt tensioner - the tensioner arm, the tensioner pulley and the damper. The tensioner arm should pivot smoothly about the crankshaft axis and not at all about any other axis. If the arm clicks as you pivot it about the crankshaft axis or wobbles such that the tensioner pulley isn't coaxial with the other pullies, the tensioner is building the fan's appetite for radiator guts :eek The tensioner pulley should spin smoothly and quietly and shouldn't wobble. MB label dampers are more cost effective than discount brand dampers. The heim end busings in discount brands don't last nearly as long as MB brand counterparts so you'll replace dampers more frequently. There are black plastic caps over the central bolts that hold the tensioner arm and tensioner pulley. The arm bolt takes a 12mm hex bit, the pulley bolt takes a 6mm hex bit.

Sixto
87 300D