190d belt tensioner noisy at low rpm.
 

i was told by my mechanic that belt tensioner on my 87 190d is worn and causing nosise at idle.what does it take to replace it,where exactly is it?

Not familiar with your exact setup but if it is similar to my 603 there is a small shock absorber opposite the tensioner spring. This shock wears and the bushings on the ends wear out and rattle at idle. I know on mine it needs replacement about every 50K miles. Simple to replace and the shock is about $40. Hope this helps.

Also replace the spring while your at it. Make sure the pivot pin is torqued to 90Nm as well.

my engine has 2 shocks in the front by fan,is the tensioner that round thing between them,do i have to take belt off to replace it,shocks look ok

Shock can "look" OK but be totally worn out. Do a search in the DIY section for "belt tensioner" - there should be several how-to's. Better yet, obtain a copy of the FSM on disc.

Shock on left side, spring on right. You will need the tire tool or a gigantic screwdriver to release tension, then do the change out.

Make sure you have a diagram of how the belt goes back on.

Hugh Sr