Today I went out to start my 90 Trans Am 350 TPI and it started up just fine. After about 2 minutes of running I started hearing a loud whirling noise almost like a bad pulley???? Assuming it was the alternator pulley I grabbed a screwdriver and put the metal end on the alternator and the other end to my ear but the noise wasn’t coming from there. As I was looking around the engine bay trying to see where the noise was coming from it suddenly stopped? I let it run for a while but the noise didn’t come back. I turned the car off and started it again and no whirling noise???? Any ideas? I did change the AC compressor last summer but didn’t have any issues? Thanks in advance.

 

Description sounds like AC compressor.

See my signature for a helpful logical shortcut.

 

Thanks for the reply. When you say “see my signature” where is that? Thanks

 

It's the quote below the post itself. Might not appear if you're using just a phone. It reads:

 

Thank you and William

 

I have an 89 Formula 350 TPI that started intermittently doing the same thing early last year. Last month I found the culprit, was the passenger side electric fan motor. I was able to find this (only while it was making the noise) by taking a long screwdriver and touching the metal end to various metal components at the front of the engine while the screwdriver handle was to my ear. Need to be careful doing this while the engine is running to prevent any injury or damage. AC compressor, alternator, water pump & power steering pump were fine, did not find it until I touched the passenger side fan motor housing. When I removed the fan motor it would squeal just by spinning it with my hand due to dry bearings rusty bearings. I replaced with one from Advanced Auto (Carquest) that has a limited lifetime warranty (last year my driver side fan motor quit working and I replaced with the same, fitment and quality very good!). I hope this helps!

Carquest Premium 2 Pole Radiator Fan Motor Part # 35656 (made in Canada)

(61 reviews)

limited lifetime replacement
$44.99
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Thank you so much for the detailed and courteous response. I never thought about the fan. Hopefully I will look into it. I really appreciate the suggestion.