prism low RPM rattle especially with AC on

[DanielinTheLions]

I've got a 2001 chevy prism with a bit of a rattle coming from under the hood. I removed the accessory belt, started it up and no rattle. So it's definitely something driven by the belt. Interestingly it really only makes the noise when the engine is under load (in gear or AC turned on) at lowish rpms. The best way to hear the sound is to put it in gear, turn on AC, keep foot on brake, and give it a little gas. I notice it during stop and start driving with the AC off and it gets significantly worse when the AC is on. I spun all the various pulleys while the belt was off and the tension pulley was definitely bad so I replaced that, but the rattle remains. It seems like it must be the AC compressor except that it rattles with or without the AC on. That's the part that confuses me. Aren't different bearings in the compressor in use depending on whether or not the clutch is engaged? If it was a problem with the compressor I would expect it to rattle when off (clutch pulley) or rattle when on (problem in the compressor itself). Thoughts?

 

[friendly_jacek]

Did you replace only tensioner pulley or the entire tensioner?

Tensioners were defective in 2002-2003 corollas and there is a TSB for that. Mine had the same noise as yours and I replaced tensioner myself, as it was outside warranty when I discovered that.

Not sure of 2001.

 

[DanielinTheLions]

Unfortunately I only replaced the pulley itself. I should check and see if there is a TSB on the 2001 model too.

 

[friendly_jacek]

I tested mine at idle speeds and the tesioner was bouncing up and down a lot (even without noise). There was also some oil leak from the damper. That convinced me it was bad.

 

[DanielinTheLions]

Well seems like I noticed mine being in a similar condition the last time I looked at it...Sounds like it could be the solution. Thanks.

 

[DanielinTheLions]

Well turns out it was in fact the tesioner that was causing the rattle. Replaced it and the noise is gone.