[Firm]

So replaced my serpentine belt a few months ago - pretty easy job. But my belt still makes a bit of a squeal for the first 30 seconds or so of run time in the mornings. I figure it's probably because my tensioner is getting weak?

Does anyone have instructions on how to replace this? I am trying to guage whether it's something I should attempt myself, or if I should just wait till my next service and let my indie do it.

Thanks,

Zack

 

[Killahkal88]

So replaced my serpentine belt a few months ago - pretty easy job. But my belt still makes a bit of a squeal for the first 30 seconds or so of run time in the mornings. I figure it's probably because my tensioner is getting weak?

Does anyone have instructions on how to replace this? I am trying to guage whether it's something I should attempt myself, or if I should just wait till my next service and let my indie do it.

Thanks,

Zack

This is what my ALLDATA shows me.

1.1 Remove the fan shroud (3).
1.2 Remove electric fan (1)
2 Remove poly-V-belt (2)
3 Rotate tensioning pulley in anti-clockwise direction and lock
NOTE: Lock tensioning pulley with drift or pin (6, diameter 5 mm).

4 Unbolt shock absorber (7) at coolant pump
Shock Absorber Of Belt Tensioning Device To Coolant Pump Housing - 35 N.m

See "Special Tool" given below.

5 Unscrew bolts of tensioning device (5)
Self-tapping Bolt Of Belt Tensioner To Timing Case Cover
Thread Not Pretapped - 35 N.m
Thread Pretapped - 25 N.m
See "Special Tool" given below.

6 Remove tensioning device (4)
7 Unscrew shock absorber (7) at tensioning device (4)
Bolt Of Belt Tensioner To Timing Case Cover - 25 N.m

See "Special Tool" given below.

8 Install in the reverse order

 

[Firm]

Awesome, thanks!

Pretty sure I don't have that shock absorber, but I've read that some do and some don't, it's not really consistent.

 

[Kobus]

None of the All-data stuff point 1 is relevant for the SLK320. Start at point 2.
If you have the old-style tensioner, it is way overdue for a replacement. The new style has a 'bolt' head cast into the lower corner to release the tension with, while on the old style you had to use the torx in the center. Also the old style had a 2-part metal pulley and were prone to sudden disintegration.
While you at it, also check the plastic idler wheel (top left looking at the engine). It develops cracks at the rear where you cannot see it. Remove the idler wheel and inspect. It's quite a cheap part so it may be wise to replace it if you have more than 80,000 miles on the car.
You can also check the W210 forum for writeups on replacing the tensioner and the idler wheel.

 

[Killahkal88]

Also to add, an idler pulley should normally spin with resistance meaning that it should not spin freely when you spin it. You can check by taking the pulley out and spin it by hand. Also while spinning, it should be quiet - doesn't sound dry.

 

[Firm]

Thanks Kobus, so you're saying that I don't need to remove the electric fan or shroud?

My car just hit 80,000 miles and I am pretty sure the tensioner is original, so I guess it's a good time to do it - now I've just gotta find some spare time...