The belt tensioner on my ‘89 300SEL rattles when idling in Drive (about 600 rpm). The rattle disappears when in Neutral (about 750 rpm). Two questions:

1- Does the tensioner need replacing or should I just replace the tensioner shock absorber? I’m thinking if the tensioner is bad then the rattle should continue regardless of the slight rpm variation.
2- Is the drop in rpm normal when shifting into D from N?

TIA

__________________
Riadh
'89 560SL Rauchsilber
And what is good, Phaedrus, and what is not good -- Need we ask anyone to tell us these things?

Hi,

The tensioner shock bushings wear out (likely causing your rattle), the tensioner assembly is probably OK if it hasn't been broken by overtightening the adjuster.

The change in RPM between N and D is normal.

I agree with langpfiefe, but I would also say that you just don't know until you take it apart and examine.

Good luck,

Ditto--

I agee with all. Check it all for sure, don't wait around, it could lead to other problems.

Thanks all for the replies.

__________________
Riadh
'89 560SL Rauchsilber
And what is good, Phaedrus, and what is not good -- Need we ask anyone to tell us these things?