Alternator Belt fun :-\

[Chooch84]

Hi,

So a couple of weeks ago it was decided that I would take my Volvo out and about to stretch its legs via Warwick Uni as well as a National Trust site nearby.

Long story short, the site we picked was closed so we ended up going towards another where the Alternator belt decided to shred itself. I was able to make it to the 2nd National Trust site, but I was towed home by the AA. The belt itself was a Contitech belt which was less than 3-4 years old. I did notice a little bit of fraying beforehand but I thought it might have something to do with the width of the belt.

I've figured out that there was too much movement (front/back), this had come about from switching over to Polyurethane bushes. I've created a 3D-printed tool to help me sort out the alignment (yes I could have used a straight edge and taken some measurements...). See link. See the images below for the tool.





With a couple of large M8 penny washers, I was able to set the position correctly, by pushing the Alternator forwards.

The question that I have now is how much tension should be on the belt, is there a way to test which isn't subjective? I've set it to where I think is correct, but I can see deflection in the belt whilst the engine is running. I was thinking of using a suitcase weighing scale to pull on the belt, but I don't think there's a known value to reference against.

[Forrest]

It might be worth double-checking the condition and correct positioning of the alternator bushes and harmonic balancer before introducing permanent modifications to compensate.

As far as belt tension is concerned the most accurate non-subjective way to test it is with a krikit belt tension gauge. However, these can be a bit fiddly to use. Not to mention hard to find when you have put yours in a “safe place” a few years ago. Consequently, the method I generally use is to tension the belt until you can flip the longest edge by 90° and no more. That usually seems to give a pretty reasonable and consistent tension for these accessory belts.

[Metallo]

Originally Posted by Chooch84

Hi,

So a couple of weeks ago it was decided that I would take my Volvo out and about to stretch its legs via Warwick Uni as well as a National Trust site nearby.

Long story short, the site we picked was closed so we ended up going towards another where the Alternator belt decided to shred itself. I was able to make it to the 2nd National Trust site, but I was towed home by the AA. The belt itself was a Contitech belt which was less than 3-4 years old. I did notice a little bit of fraying beforehand but I thought it might have something to do with the width of the belt.

I've figured out that there was too much movement (front/back), this had come about from switching over to Polyurethane bushes. I've created a 3D-printed tool to help me sort out the alignment (yes I could have used a straight edge and taken some measurements...). See link. See the images below for the tool.





With a couple of large M8 penny washers, I was able to set the position correctly, by pushing the Alternator forwards.

The question that I have now is how much tension should be on the belt, is there a way to test which isn't subjective? I've set it to where I think is correct, but I can see deflection in the belt whilst the engine is running. I was thinking of using a suitcase weighing scale to pull on the belt, but I don't think there's a known value to reference against.

Hi there,

When I read your post and saw your pictures, I had a laugh, as your issue is basically identical to mine, see images.

I have a 940 SW 2.0 Turbo 1997

I also thought about the same solution, but my questions is:

Did you resolve that way?

I am asking because in my case, the alternator should be moved forward by at least 2mm. I can add a couple of washers on the back bushing, but this is to prevent any play really, because the front bushing will prevent you to move the alternator forward, am I right?
If I am lucky, removing any play may suffice, if not, I really do not know how to fix this.

There are no issues with the harmonic balancer, so clearly parts are moving with the years...and my bushings are new, genuine Volvo.

My belt was visually perfect two days ago, after 10K Km what else should I expect? However, today suddenly broke so bad, that my A/C belt slipped off the pulley, (found it at the bottom of the splash screen, intact).

I can only attribute the cause to the misalignment.

Any suggestion is always very welcome.

Thank you!
Alex