Replacing Serpentine Belt and Tensioner

[mbd]

I took my car into the dealer to diagnose a problem I'm having with the car running rough. While dealing with this problem, the mechanic noticed that the serpentine belt was cracked and the tensioner was loose. I did notice the whole thing was noisy and rattled. The dealer recommends replacing them both. I can see getting the belt replaced but is it really necessary to replace the tensioner? Could a loose tensioner cause any damage other then making noise? It's $250 CDN to have the tensioner replaced and $60 CDN for the belt.

[Chris Corolla S]

If the bearings are shot in the tensioner it should be replaced. It is very important to have the moving parts of the car running smoothly.
If you are concerned about the cost try doing the work yourself and just buying the parts. Replacing a belt is very simple. Purchase a repair manual for your car to see if replacing the tensioner pulley is something you think you can do.

Good luck!

[cobrajet25]

A bad tensioner with too much play in it could actually do damage to a new belt, resulting in possible breakage. It could also cause the engine to "throw" the belt, which is when the belt slips off of the pulley while the engine is running. Then you will need ANOTHER belt, and still have to deal with the bad tensioner. When tensioners go bad, it is usually because the belt was installed too tight. This causes the bearings inside to wear out, get sloppy, and wobble, which results in noise and maybe belt damage. Change the tensioner and belt (or have it changed), and be sure the belt is tightened to the proper tension. Good luck! Regards, Aaron

[mbd]

Thanks for your replies. I took a look at the belt and and it isn't damaged at all. According to the Haynes manual, the pattern of wear that is on the belt is normal. I also don't think the tensioner needs replacing. I think the dealership was just trying to sell me something I don't need.

[Chris Corolla S]

Well the haynes manual has good pictures of what to look for in a worn belt. It probably says how to diagnose the tensioner as well. If you grab it and try to wiggle it and can't feel any play, then it's probably OK.