Thread: Symptoms of a bad belt tensioner

Hi everyone,
I have a problem with a 2002 grandprix 3.8l SC
It has a metallic knocking sound coming from the passenger side of the engine. Sort of like a ball bearing in a can. I reviewed previous posts for the last hour to see if anyone else had a solution and looks like it can be several things, so heres where I am.

Engine knock is louder when the air conditioner is turned on.When turned off it quiets down considerably. I removed the super charger belt and still have the noise. I used a long screwdriver as a stethoscope and tried to isloate and found the accessory belt tensioner has a pretty good vibration to it. Supposedly the pulley on the belt tensioner was previously replaced along with the power steering pump in the past. I removed the accessory belt and started the car for 10 seconds and the noise went away. I spun and checked for play/looseness all the pulleys on the engine, 8 total and no trouble found. The water pump doesn't leak from the weep hole and wasn't for sure if the accessory belt tensioner assy can go bad hence the vibration when the engine is running or if some other component i.e.(water pump, bad pwr streering pump) is transferring it to the belt tensioner. I can't afford to shotgun the problem, have limited funds.
Thanks for reading, sorry so long, just wanted to be concise.

Bearing in the acc. belt tensioner, replace the belts while your at it too, if they are needed.

Is this common on these engines, having to replace the acc. belt tensioner?

Thanks reveregtp I'll let you know
Are there bearings in the belt tens. assy bracket where it pivots? I thought it was just a big spring with nothing to cause the knocking I'm hearing. I know the pulley has a bearing that can go bad.

I just got done changing the harmonic balancer and it fixed the problem.

Only issued I had was that I couldn't use a harmonic balancer puller to remove the old one because the 3 bolts you use to thread into the balancer were shifted, because the balancer was toast. So I used a 2 jaw puller instead and it worked great.

If you guys ever have any knocking, clacking sound coming from the belt side of your engine don't forget about the harmonic balancer in addition to the pulleys.

Thanks for everybodys help!