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TH400 Help

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Old Aug 3, 2007 | 11:29 AM
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I recently installed a Chevy small block and a TH400 in a '73 Firebird. The transmission was bought from a family member who claimed it worked fine. The stock stuff in the car was a BOP 350 / th350. I read the kickdown on the 400 is electric, not vacuum or mechanical. Everything else is pretty simple. My delima is that I have trans fluid boiling up and out of the dipstick and I need to know the reasons why so I can correct it, or replace the trans if need be.

Thanks in advance...
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Old Aug 3, 2007 | 12:49 PM
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Is it properly filled?
Overfilled can cause it to aerate the fluid and spew over.

The vent tube may also be clogged.
It could also be an internal seal leaking on apply causing pressure.
Does it do it on startup?, while running in any gear, or only in a certain gear?
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Old Aug 3, 2007 | 01:19 PM
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The first time I ran it. I'm not sure of how much fluid I put it. All parts were dry so I would keep adding as it made it through the cooler and what not. I suppose I could have added too much.
It doesn't do it on start up, it hasn't been as extreme while in neutral or at idle.
I've only moved the car in 1st and rev so I can't answer if it's any specific gears.

I'll check the vent tube! I didn't think of that. That I'll do tonight!
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Old Aug 3, 2007 | 01:23 PM
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Well... how many quart bottles did you open when you were filling it?

g
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Old Aug 5, 2007 | 03:45 PM
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The 400 has a vacuum modulator on the passenger side. Are you sure that it is a th400?
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