1996 Toyota Land Cruiser 4.5L Belts belts hoping off

[haryv]

The sole Toyota Landcruiser we work on has become a real pain in the back area.

Car was towed in on Tuesday. We had an opportunity to take a look that afternoon and discovered broken main belts but the ac belt was in good condition and in place. Technician checked and found excessive play in the tensioner pulley for the two main belts. Also removed the ac belt and found bearing in this tensioner very grindy(bearing failing). We ordered 3 new belts, new ac tensioner pulley and main belt tensioner pulley. Installed these items yesterday afternoon and the car went out the door for a test drive.

After test drive, technician rechecked belt tension and found the double main belts have walked forward on the double tensioner pulley to the point the front belt is half way off the new tensioner pulley. AC belt is fine and running as it should be.

We checked with straight edge to ensure alt, crank and tensioner pulley are lining up correctly and all seem to be. Also removed belts and checked to ensure alternator pulley does not have play allowing it to walk forward or back. It is nice and tight.

Has anyone ran into this before? Any suggestions!

 

[ToddD]

You have a tensioner pulley? Isn't the Alt the tension adjustment point for the belts? I don't really understand how these belts can wander anywhere. It is early and I'm often easily confused... there must be something I'm missing...

 

[Kernal]

The AC belt pulley is adjustable for tension on the AC belt. The alternator belts have an idler pulley that is non-adjustable; not the belt-pulley expert but it's function AFAIK from reading other threads is to prevent the belts from slapping around, not to put tension on them. The Toyota alternator belts come as a matched set. Here's a few photos.

 

[Ebag333]

not the belt-pulley expert but it's function AFAIK from reading other threads is to prevent the belts from slapping around, not to put tension on them.

Yup, doesn't do much, IIRC you can remove it completely without any issue.


Some pics would be helpful. Based solely off the (very limited) info here and no pics I might guess that he's trying to route the belts in a serpentine fashion (back and forth) instead of a more circular fashion. Common mistake that's made, especially when you just grab a belt off the shelf that is not the OEM length.

 

[Frankencruiser]

When I bought my first 80 one of the belts had twisted to the side, but was routed properly. I replaced them with Dayco Top Cog belts and never had the problem again. My guess is it was a bad belt, or improper routing.

 

[Grench]

IIRC...

The alternator mount tensions the belts. It has a lock screw/bolt coming in from one side and then an adjuster bolt coming back up toward the battery tray. Quite a few people remove the battery tray when servicing the alternator because of this bolt - it can also be addressed from underneath with proper extensions and loud use of four letter words.

Matched set belts are required on this. They literally need to be cut off the bandberry sequentially so that they're as close to exact length and construction matches as possible. Because they tension together - if they aren't matched you'll tension the small one and the ever so slightly larger one will slip & roll.

 

[jamisobe]

A year or two after owning my LC(1999 or 2000), I had an issue with belts jumping off, flipping over and making noise. I went through all kinds of attempts at fixing the problem. What I learned was very surprising. The after market belts I kept buying were slightly too narrow and did not ride in the pulley channels correctly. When I put on Toyota replacement belts all the problems stopped. I am not a Toyota parts purist, but I will only use Toyota belts.

 

[landtank]

A year or two after owning my LC(1999 or 2000), I had an issue with belts jumping off, flipping over and making noise. I went through all kinds of attempts at fixing the problem. What I learned was very surprising. The after market belts I kept buying were slightly too narrow and did not ride in the pulley channels correctly. When I put on Toyota replacement belts all the problems stopped. I am not a Toyota parts purist, but I will only use Toyota belts.

too narrow a belt will bottom out in the pulley so it doesn't ride on it's sides. Too wide a belt will cause it to ride on the lip of the pulley and not it's sides.

Best to stick with OEM