1998 xcv70 belt tensioner failure?

thaedge · Post by **thaedge** » 03 Nov 2014, 08:44

Hey all. Weird issue I'm having.

My old serpentine accessory belt works absolutely fine, but its time for replacement, its cracked on the grooved surface.

I have tried 3 different brands of belts. And after starting the car the belt starts to "walk" off of the alternator off the outside of the pulley. It's the exact same belt as the one thats on there, but it's more crisp, and the one thats on there is more supple from years of wear.

So originally, I thought this had more to do with the quality/brand of belt. But now I'm thinking it may be the belt tensioner?

Does anyone have experience with the belt tensioner failing. Does it usually cause the belt to ride off the alt. pulley?

It seems that all the pulleys are in good shape. all are in line when looking from the sides.

Could the tensioner be on it's way out, and just not holding the new crisp belt on tight enough to stay in the groves?

thaedge · Post by **thaedge** » 03 Nov 2014, 08:49

Also, in people experience. When the tensioner does fail. Is it a catastrophic failure, as in it works 0% now. or does it just stop working as well and then need to be replaced one day.

Post by **mecheng** » 03 Nov 2014, 10:40

It rarely fails, I've never heard anyone having a problem with it. If the spring breaks, it fails technically, but I think it will still apply tension, just not the ideal amount

thaedge · Post by **thaedge** » 03 Nov 2014, 11:41

So how do you know if it is no longer putting enough tension on the belt?

Do you know because the belt hops off the pulleys?

Do you think it's reasonable that it runs fine with the old belt, but an exact fit new belt does not stay on?

Post by **precopster** » 03 Nov 2014, 11:54

Remove the tensioner and check for wear allowing flex of pulleys. My old 960 tensioner did this over a period of time and killed my timing belt/valves.

Remove the idler pulley and check for excess wear. You should be fitting a PK1740 or PK1743 belt if using the new routing.

Post by **Ben850** » 03 Nov 2014, 16:26

thaedge wrote:So how do you know if it is no longer putting enough tension on the belt?

Do you know because the belt hops off the pulleys?

Do you think it's reasonable that it runs fine with the old belt, but an exact fit new belt does not stay on?

The parts are relatively cheap, other than the OEM tensioner.
Two pulleys, at approximately $20. each. they can be assessed by spinning, rotating by hand with the belt off. If they make noise, or are not easily rotated, then replace the pulley.
The belt itself is about the same price.

If you have continuing issues, it may be bearings in the components the belt is driving, i.e. power steering pump, air conditioning compressor, alternator.
That is really about it.
Each of those components can be assessed by grasping their respective pulley, and checking for excess movement, or seizure other than smooth rotation.

If you believe the tensioner is not functioning, spray a lubricant in the moving areas and wipe off any overspray. The original serpentine tensioners are pretty sturdy.
Edit: Also do what Mike said above. Good results.

Post by **cn90** » 04 Nov 2014, 07:02

1+,

When in doubt, replace the tensioner. Use Volvo or INA only.

Some people in Honda Odyssey (V6) engine had issues with serpentine belt, tensioner, serp belt walked off, sneaked behind timing cover ---> timing belt screwed up ---> engine trashed!

The morale of the story: serp belt and its associated components, when failed, can cause big-time damage!!!