Chevrolet Repair: Unusual, chevy silverado, torque converter

Question
Dear Sir,
I have a 1991 Chevy Silverado with a 5.7 litre(350) engine ½ ton extended cab 4 wheel drive pick up and recently after 288,000 good miles the engine gave up the ghost so I had another one with 97000 miles put in I bought from along time friend and this engine runs very strong, very good oil pressure, no oil smoke or anything else I can find wrong with one exception which is weird to me because I have never heard this noise in my  truck before even with the old engine.

When this engine is running I hear a noise which I can only describe as a whirling noise which changes pitch (Faster )but not so much intensity  as I accelerate but the really weird part is it seems to come from down under the dash and I can  not pinpoint it, it reminds me of when a leaf got down into the vents below the windshield of my 1977 Scottsdale pick up, I checked this one and no leaves or any other debris.

I first suspected the torque converter but the fluid levels are ok and very clean and I have always added a can of “Trans-X” to my transmission about every 10000 miles and the noise was not there before the engine quit so I am wondering if there is some sort of motor under the dash other than the heater motor because I eliminated that right away by shutting of the engine and turning on the key with the engine off because I know it runs on low all times because I have ac and no vents in the kick panels .

Can you please tell me what it might be?
Thank you  and Happy New Year
Bob


Answer
Hi Bob, short and to the point I will be. Check your fuel lines that come up along the firewall. They might be touching the cab behind the engine or down by the fuel filter. Just make sure the fuel lines are not hitting any where. I have seen this happen after a engine job!!

Have a Great New Year

Mark