High pitch squeal under acceleration

[71CHEVYSHORTBED402]

If I step on the gas I get a high pitched whistle, like a TING!........It doesn't always occur under the same RPM, and appears influenced by a rapid increase in acceleration.

I'm mostly certain I've heard the same in drive, and this has been going on a long while, despite lubing the belts and pulleys. It's just more obvious in park. Other than that, the engine sounds good. If necessary, I could create a video.

Thank you.

[Wrenchbender Ret]

That is usually caused by a belt. Try tightening the alt belt. Sometimes a fan clutch is locked up or has been replaced with a heavy duty fan can put excess torque on the belt. If a guy has removed the A/C belt it will put too much load on the alt. belt.

[stsalvage]

my one ? dose your truck have the AC compressor on it.Check as see if the compressor is locked up.the other thing is start checking bearings ALT power steering pump water pump smog pump all have center bearings.

2 take off all your belts look at your pulleys see if they look like glass in side means your pulleys need to be roughen up a little or your pullets are no good any more if your belt dose not stick up a little bit over the pullet too small of belt

[Sklptrljay]

Read through this thread. I had the same problem. Starter hitting the flywheel under acceleration/ deceleration / under load.

http://67-72chevytrucks.com/vboard/s...d.php?t=569719

[71CHEVYSHORTBED402]

Originally Posted by Wrenchbender Ret

That is usually caused by a belt. Try tightening the alt belt. Sometimes a fan clutch is locked up or has been replaced with a heavy duty fan can put excess torque on the belt. If a guy has removed the A/C belt it will put too much load on the alt. belt.

I thought so, and I bet it's the alternator belt, there's a lot of play. I put that alternator on, heck I don't remember its been so long. Those are a bear to tighten. I generally use a crow bar, but don't think I'll be doing that with the restore. Alt. and belts are being replaced anyway. Going to use an internal regulator. And yes the A/C belt has been off since 1993. That will also be restored. Thanks very much.

Edit: I bought a new fan also. Board member restores them. If it works like it looks then I couldn't be happier.

[71CHEVYSHORTBED402]

Originally Posted by Sklptrljay

Read through this thread. I had the same problem. Starter hitting the flywheel under acceleration/ deceleration / under load.

http://67-72chevytrucks.com/vboard/s...d.php?t=569719

Mine seems to occur under a load only. That said, I already know I'm missing teeth some teeth in the flex plate. Yeah, that's being replaced too, thanks.

[swamp rat]

To isolate just remove the alternator belt and ( i have done this ) find a place it will hang free without hitting the power steering belt, fire it up and rev it, if the squeal stops you know its the alternator belt. I have been thru the frustration, deglazed the pulleys with sand paper, different pulleys, over tightened to the point of destroying bearings in the alternator, new sets of belts, checked pulley alignment ect. Whats frustrating is the truck was fine for years after my rebuild, then it decided to start making noise.. I can still get it a little bit but its not near what it was.. Frustrating.

The only thing i didn't try was to remove the fan blade ( i don't have a fan clutch ) and put it back together with just the water pump pulley, if you try that it will reduce the drag on the belt and may stop the squeal?? If that works try purchasing a fan clutch.

[71CHEVYSHORTBED402]

Good advice, thank you for all the responses. I'll wait to diagnose during rebuild. With a some luck I won't have to.

[Sklptrljay]

Do you have a hi-torque starter? Both mine and the other guy's truck with that issue did.

[71CHEVYSHORTBED402]

Originally Posted by Sklptrljay

Do you have a hi-torque starter? Both mine and the other guy's truck with that issue did.

I replaced it about three years ago, but I don't remember what it is....though HT does sound familiar. I had to shim it once or twice. I'll probably replace it again, considering a new flex plate. Any recommendations?

[Sklptrljay]

Well, we both had to shim ours, or go back to a stock one.

You could also buy a starter for a '90's Chevy. Read this thread, TXfirefighter describes how he uses a (mini) starter from a '98 Tahoe as a direct bolt on replacement.

http://67-72chevytrucks.com/vboard/s...d.php?t=622405