97 Grand Prix GTP grinding at low RPM

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SVick83
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Joined: Thu Nov 15, 2012 12:14 pm

97 Grand Prix GTP grinding at low RPM

Unread post by SVick83 » Thu Dec 27, 2012 10:23 pm

1997 Grand Prix GTP supercharged makes a weird grinding noise at idle or when the RPM drops below normal idle. Could it be the supercharger itself, or a pulley to something?

 

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wildman
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Re: 97 Grand Prix GTP grinding at low RPM

Unread post by wildman » Sat Dec 29, 2012 2:59 am

Could be lots of things, lets concentrate on narrowing it down a little.
With the motor off and key out of the ignition, reach down and shake the idler pulley(s) for your belt.
Excessive play will usually rattle, squeak, whine, and make a racket.

If no play there, get a piece of hose or gas line and carefully put it to your ear while the motor is running.
Scan the engine compartment to narrow down the general direction. You can touch stationary points to listen more if needed. Check the alternator especially, they're prone to bearing wear (usually rear)
Be careful not to get near any moving parts- with your fingers, clothes, jewelery, or the hose.

Some will use a screwdriver but use the hose- it's safer.
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SVick83
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Re: 97 Grand Prix GTP grinding at low RPM

Unread post by SVick83 » Sat Dec 29, 2012 6:27 pm

The grinding Sounds like it is coming from the middle of the supercharger.

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wildman
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Re: 97 Grand Prix GTP grinding at low RPM

Unread post by wildman » Sun Dec 30, 2012 6:26 pm

Unfortunately, if the sound is coming from the supercharger then it's your problem.

Did you notice any other problems?
High water temp reading, low pick up, lag in power at take off, boost pressure gauge (if installed)?
What is the oil pressure when at idle?
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SVick83
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Re: 97 Grand Prix GTP grinding at low RPM

Unread post by SVick83 » Sun Dec 30, 2012 8:33 pm

Everything is fine. The oil pressure is perfect, the boost gauge is fine, coolant is fine, and the car does not lack any power. It will fly. The tensioner pulley near the front diagonally down from the supercharger is definitely bad. I'm going to replace thatfirst and go from there. Thank you so much for your time and for your help. I greatly appreciate it.

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wildman
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Re: 97 Grand Prix GTP grinding at low RPM

Unread post by wildman » Sun Dec 30, 2012 8:45 pm

You're welcome- glad you found a wobbly pulley to be honest because those superchargers can be a pain- hurts the wallet a bunch too.

Hopefully it's just the pulley bouncing and the sound is traveling up the body of the charger. Keep us informed when you get that changed :)
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SVick83
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Re: 97 Grand Prix GTP grinding at low RPM

Unread post by SVick83 » Sun Dec 30, 2012 8:47 pm

I will. And I know. The cheapest supercharger I found was $700 with $180 core charge. I can't afford that. $50 for the pulley I can deal with.

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