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Old 04-12-2006, 08:38 PM
NASCAR314 NASCAR314 is offline
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TH-400 "whirring noise" at med. RPM's

Stock 1973 Chevrolet Turbo 400 transmission in my Street Rod:

It has developed a noise present at acceleration from about 1,000 rpm's up to about 3,000 rpm's. Worse under load. Less in nuetral. Sounds like a "whirring" noise. Not a Grinding, scraping, or skreching noise.

It is not the water pump, alternator, belts, cooling fans, or timing chain (checked those). Seems to be originating from the bellhousing area, or flywheel area.

Trans. seems to operate just fine, shifts properly, pulls strong, ect..., Transmission fluid is full, and looks and smells like new.

Almost sounds like a "Blower Belt" on a Blown motor from inside the car. Or those "noisy" timing gears. It does change pitch with increase in RPM's

This noise seems worse during colder weather, and then dissapates somewhat as engine / trans. warms up.

Any idea's? could it be the transmission fluid pump? torque convertor?