C280 Belt Tensioner
 

I was wondering if the belt tensioner is manually adjustable or automatic.

I have a 96 with the new style tensioner (w/o shock). If it is manually adjustable, what's the procedure? If it is automatic with no manual adjustment, can a defective belt tensioner cause the belt to be too tight? Or only loose?

The belt seems very tight compared to another c280 I've checked. Very little deflection when pushing down on it. I've had a developing whining sound (for a few years actually) and I wonder if too much tension has caused bearings to wear prematurely and causing the sound.