Drive Belt Comes Loose !!

[TownCarTechi]

I replaced the drive belts on my daughter's '99 2.4L Galant in August. Now, over the past three days, the belt that drives the P/S and A/C has wound off several times. I've checked all the pulleys including the tensioner and they look okay.

The belt I purchased from AutoZone was a Duralast 539K5 which has now been replaced by 540K5. Luckily, AutoZone was willing to exchange the belt so I'm going to attach then new one tonight and hope it doesn't wind off. The new belt 540K5 seems to be slightly thicker than the 539K5.

I also noticed with my naked eye that the engine pulley doesn't seem to line up perfectly with the P/S and A/C pulleys (engine pulley is at the top on the attached picture), but those two pulleys (P/S and A/C) do line up with each other. Has anyone else noticed this?

[Obysk]

Is the belt tensioner automatic or do you have manual control over the tension of the belt?

If you have an automatic tensioner I would start by replacing it. More often than not this type of problem is caused by incorrect or insufficient belt tension. Most times you won't be able to "see" a bad tensioner and without a new part to compare it to you won't be able to test the correct tension.

As far as pulley misalignment goes, yes this can be an issue, but if you have never removed or replaced any of your pulleys (and none are damaged) then you can assume that they are sitting in their factory original positions.

I have seen as well the smooth idler pulleys "round off" on the edges causing the belt to eventually ride off the pulley. Make sure you have a very good look at these pulleys.

Let us know what happens and good luck.

[TownCarTechi]

The car has a manual tensioner and the pulleys have never been removed (until now). A friend determined that the harmonic balancer is bad. On my daughter's engine, the two engine pulleys (one for Alt and the another for P/S, A/C) and the balancer is combined into one part. The friend says he can get one for $75 (RockAuto lists for $120) and install. If this takes care of it, I'll post again with our success.

[TownCarTechi]

Indeed the harmonic balancer was worn and this is why I perceived the outer engine pulley to be out of alignment with the P/S and A/C pulleys. Replaced it and all is good with my daughter's car.

[stream]

our Galant had the nasty belt squeal and my husband fixed it but now it is back again, perhaps this is why - very annoying