Replacing a serpentine belt? [Archive] - SaabCentral Forums

: Replacing a serpentine belt?

29th January 2011, 10:34 AM
Hello there folks ! i was sitting in a drive thru line last night and i noticed an increasing whining noise, when i started to pull away my battery light came on and i lost my power steering, i was close to home so i drove maybe a mile until it became impossible to drive. upon inspection i noticed that my serpentine belt had came off, now mind you it is old but it wasnt broken off. Any ideas of what the culprit is or a checklist of what to potentially look for? Also i am limited on my phone for checking threads, i was wondering if anyone knew of a thread for self repair of the belt? Thanks in advance !

29th January 2011, 11:35 AM
your idler pulley properly seized up. i would replace this along with a new belt.

29th January 2011, 09:31 PM
I'm guessing the tensioner gave out. Same thing happened to mine pretty much right when I bought it. It was a continental belt with less than 10k miles that got completely eaten up.

Basically, you remove the wheel well to gain access. The tensioner bolt is reverse threaded.

I didn't want to make a tool to hold the tensioner, so I routed the new belt everywhere but the idler roller. Then I had a helper release tension while I slipped the belt onto the idler. Voila.

Pretty expensive things. I grabbed a pretty new one from the local junkyard for $10. New is probably around $100-150 iirc.

Make sure all your pulleys spin freely.

29th January 2011, 09:33 PM
yeah i 2nd that. i meant to say tensioner not idler pulley sometimes i get mixed up. lol.

30th January 2011, 05:32 AM
Really good write up here :
I`ve done it this way a couple of times. The `special tool` is easy enough to fabricate. I think you may as well put in a new tensioner as well. Watch out for the old one flying apart when you unbolt it - missed me but would have been very painful otherwise!! Worth putting a couple of strong tiewraps or wire round it.
Good luck!

30th January 2011, 05:42 AM
Almost forgot this:

Which is excellent but difficult to read - I copy it into word & reverse the colours.

30th January 2011, 01:15 PM
Really good write up here :
I`ve done it this way a couple of times. The `special tool` is easy enough to fabricate. I think you may as well put in a new tensioner as well. Watch out for the old one flying apart when you unbolt it - missed me but would have been very painful otherwise!! Worth putting a couple of strong tiewraps or wire round it.
Good luck!
Oops, I forgot to post that link :)

4th February 2011, 07:56 AM
Tto replace the belt I simply place my socket on the tensioner wheel bolt, its reverse thread so with a bit of extension on the ratched handle you simply pull it anti clockwise to release the tension on the belt and flip it off. Takes 10 seconds and is simpler than making and using a special tensioner tool.

8th May 2012, 11:45 PM
My car is an auto. I am planning on replacing the belt soon. But today I heard the belt making a loud noise but as soon as I put it into park no noise. Any ideas what that could be?

9th May 2012, 12:10 AM
Now the belt is squealing whether it is in drive or into gear. Is it just the belt or could that be the tensioner going bad?

9th May 2012, 01:05 AM
A screaming noise is generally caused by the belt surface moving at a different speed than a pulley.

Can be caused by either:

Resistance to rotation of a driven component (e.g. failing bearing in the P/S pump, A/C compressor or alternator - and rarely the water pump)

Lack of belt tension at the contact area of the pulley (due to a weak tensioner/dampener).

A bad bearing in the idler or tension pulley usually makes more of a grinding/clicking noise. A squirt of WD-40 into the bearing will usually quiet a bad bearing long enough to pinpoint the source of the noise.

To check overall belt tension, pull up on the upper horizontal run of the belt. It should require a good effort to compress the dampener springs. Also, when you release the belt, the slack should immediately be taken up.

9th May 2012, 01:10 AM
Think I pin pointed the issue. The belt is slipping g off of the a/c pulley. Its like 1/4 off of it

9th May 2012, 04:21 AM
It's time dude - you have to bite the bullet. You're going to break down sooner than later. Worst case, water pump stops pumping & engine overheats. If nothing else, renew the belt and tensioner.

Also, have the pulleys on hand when you do it. If you find your current bearings to be shot - they'll be right there. If you find that yours are okay, you can always turn the new ones back in for a refund.

Belt renewal isn't the hardest job in the world, but it still sucks to do it twice. Plus there's a good chance of wrecking your new belt, overheating & towing if a pulley fails in operation.

Plus, you have to do the tie rod end and hub on that side. The wheel well has to come out for that (as it does for the belt, tensioner and pulley job). Might as well do them all at once.

9th May 2012, 04:37 AM
I just hope I can get the pulleys in very soon. I highly doubt that any auto store will have them in stock. I was more than willing to change out all the idle pulleys and tensioner puller and water pump. I was planning on doing that before all of this happened. What would have caused the belt to slip off of the pulley?

9th May 2012, 07:02 AM
The ribs on the drive side may be worn off allowing it to walk up and over the outer ridge on the pulley (twist it and inspect).

But the far more likely cause is the belt tensioner. It's not just the heavy spring under compression that maintains proper belt load - it also functions as a dampener.

Think of it as a little shock absorber. It is filled with a high viscosity fluid. A series of tiny passages and a ball check valve control the flow of the fluid to accomodate transient changes in belt tension/slack.

This drawing and text can explain how it works better than I: ( PG)

The drive for auxiliaries has an automatic belt tensioner which is easy to service and has a long working life. The operating principle of the tensioner is similar to that of an hydraulic cam follower. On a momentary increase in the load on the tensioner, compressing it, the ball valve closes, preventing oil from flowing out of the cylinder but forcing (see image) to take place through the minute gap (1/100 mm) between the piston and cylinder wall. On a momentary reduction in the load on the tensioner, allowing it to expand, the valve opens and oil flows into the cylinder. A powerful coil spring in the tensioner always maintains a certain level of tension, regardless of whether the load on the tensioner is increasing or decreasing.

9th May 2012, 09:26 AM
Is the tensioner pulley and idler pulley the same part #? Oriellys show it as the same.

10th May 2012, 08:56 AM
Tensioner pulley: (

Bearing ID = 12.3mm

Idler Pulley: (

Bearing ID = 17mm

16th May 2012, 04:27 AM
For the tensioner pulley tool instead of welding the end bolts could I just tightened the bolts with nuts instead. I do not have a welder.

2nd July 2012, 05:46 AM
Had to change a serp belt by myself yesterday. It sucks.

I made this tool from a paint roller handle. The round stock it's made from fits exactly into the crank arm slots. Just bend to the dimensions and shape as shown. ( ( ( ( ( ( (

To use:

Have the tool in your right hand

Reach in over the fender with your left hand and grab the belt on the horizontal run between the A/C compressor and alternator.

Haul up (hard) on the belt until the damper/tensioner is fully compessed.

While maintaining your pull on the belt, reach under with your right hand and snap the tool into the slots on the arm. Hook the top over first and then push in on the bottom. Watch from the top.

Let go of the belt, remove the bolt (CW) from the tensioner pulley and set the bolt and pulley aside.

Pull the belt out.

2nd July 2012, 10:18 AM
If the idler or tensioner spins a little too freely, the bearings are probably dry and should be repacked.

6th July 2012, 09:29 AM
Twinsen is exactly right - but I think both of these bearings are ZZ's (sealed) and repacking them is not an option.

Contrary to conventional wisdom, a new (or good used) sealed bearing, should offer at least some resistance to rotation.

That's not to imply that it should feel rough or have sticky points as you rotate it, but it should not freewheel at all.

If it turns too easily (and runs on with the flick of the hand) it's not necessarily junk but it's past it's prime.

If the bearing in question is hard to access, or is part of a critical system, and you are already have it out - it might be wise to change it.

6th July 2012, 09:40 AM
Chengny, the black rubber ring on the bearing can be lifted out to expose the balls. There is a floating plastic carrier ring which keeps the balls evenly spaced. The ring can be popped out and the balls moved to one side. This will allow disassembly.

6th July 2012, 11:21 AM
Thanks! Always wanted to do that, but never thought it would work.

But, after reading your method I did a quick search. Sure enough - people do it!

Turns out that, if one is careful, the seals can be popped out intact. Use a sharp blade and remove both sides. Flush the old hard grease out, repack and snap the seals back into their slots.

Sounds good on paper anyway.

l give it a try next time I have a sealed bearing out.