Rattle
 

300SDL

I have begun to notice a rattle coming from the engine when idling. Does not seem to be present at any other point when driving. Timing belt was changed at 160K, and it is now at 291K so that is again due. Could a loosened chain be the problem??

Also for 300SDL owners. I had a long period of ABS problems. Mercedes tried to find it, so did several other shops. Said the sensors where failing. I just had the upper control arm changed, guess what the ABS is working fine now. It has most likely been bad since I bought the car, but if you've had the same problem that could be the cause.

Yes mine rattled when I needed to change the chain, actually the rails where broken, that was the rattle sound on mine.

What about the timing chain tensioner?

I will have to figure out how to check those things. I probably have to break down and get the CD thats available. Is it a big job to change the chain or the tensioner??

I recommend that an experienced MB tech diagnose the rattle to determine what's wrong before you do some major damage. Unless you're an experienced DIY'er replacing the timing chain and the tensioner is best left to a trained tech.

Do you notice a difference between idling in drive and neutral? The fan belt tensioner can be the cause of some rattles. My fan belt tensioner rattles when idling in drive. The rattle goes away when idling in neutral or when the rpm is increased slightly.

Could be the lifters? It is hard to tell without hearing it. I'd have someone check it out.

131k miles is nothing for a timeing chain on a 603, that chain should be good for at least another 100k-150k miles. Provided the oil is changed.