whine under the hood

[gtowner1265]

hi, i have a stock 73 opel gt with an automatic tranny. As the engine turns past 4600 RPM's, a loud whine develops under the hood. Anyone know what this could be?? It happens all the time while driving. I've only tried it once while on neutral and it made the noise. I was scared to try more that way cause i think i read somewhere that revving the engine too high without load is bad.

[opelwasp]

Originally Posted by gtowner1265 hi, i have a stock 73 opel gt with an automatic tranny. As the engine turns past 4600 RPM's, a loud whine develops under the hood. Anyone know what this could be?? It happens all the time while driving. I've only tried it once while on neutral and it made the noise. I was scared to try more that way cause i think i read somewhere that revving the engine too high without load is bad.

Your water pump may be going bad. Revving the engine too high anytime can be bad, but I wouldn't worry about 4800 RPM's.

[BMWonly]

Originally Posted by gtowner1265 hi, i have a stock 73 opel gt with an automatic tranny. As the engine turns past 4600 RPM's, a loud whine develops under the hood. Anyone know what this could be?? It happens all the time while driving. I've only tried it once while on neutral and it made the noise. I was scared to try more that way cause i think i read somewhere that revving the engine too high without load is bad.

Sounds like a slipping alternator belt. Try tightening the belt a little - not too much since that's bad for the alternator and water pump bearings.
I had that too above 3000 RPM a while ago, and that fixed it.

Dieter

[tekenaar]

Try things already mentioned . . . another thought, 5- or 7-bladed WP fan? 7-bladed fans are particularly noisy, high pitched whine, at higher RPMs! . . . nature of the beast, I'm afraid.

[Aardvaark]

Try isolating the noise using a 2 or 3 ft length of hose as a stethoscope
holding one end to an ear and searching for the source. Have someone rev the engine
while you're doing it. This might be kind of scary.