1999 Pontiac Grand Prix leaks tranny fluid out the transmission vent and dipstick reads empty

Bromeliad

Newbie
Joined
Mar 31, 2020
Messages
3
Points
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Make
Pontiac
Model
Grand Prix GTP
Year
1999
Miles
215,000 kms
Engine
Supercharged 3.8l L67
I recently rebuilt the 4t65e-hd transmission on my 1999 Pontiac Grand Prix GTP and when I started it for the first time, transmission fluid started leaking out of the overfill valve but the dipstick read empty. I ran it through all the gears and after 10 minutes of running, it still comes out the overfill valve. When I put the vehicle into drive,I have to rev the engine up to about 3000rpm to get the vehicle to move. does anyone have any ideas on what could be going on?
 

stu

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What are you calling an overfill valve?
 

Bromeliad

Newbie
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Mar 31, 2020
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Sorry, poor choice of words. I'm referring to the transmission vent on the top of the transmission that let's air out of the transmission and also fluid when it's overfilled.
 

bp042665

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Nov 26, 2012
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before you installed the channel plate did you use updated metal gasket the paper 1 have a problem of blowing out and line pressure dumps into the channel below the vent
 

JackC

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bp042665 and grcauto are both professionals and I would trust the info they provide.
bp042665
has his own transmission shop and has worked in that feild for years.

I feel they have solved your problem. Let us know.
 

bp042665

hunting nut
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Location
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bp042665 and grcauto are both professionals and I would trust the info they provide.
bp042665
has his own transmission shop and has worked in that feild for years.

I feel they have solved your problem. Let us know.
thanks for your trust I have been doing this like 39+ years and have owned my shop for 20 years come july
 

miketx

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Sep 3, 2020
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You don't reuse them.
Why? I've reused the plate on every one I have worked on.

To the OP. if fluid is shooting out the vent and you have to rev it up to 3000 to move, it sounds like it out of fluid. Is it possible you overfilled it at first? How much fluid did you put in it to begin with? Perhaps you could try to make sure it's full and then if the the flow from the vent stops, drive it if possible.
 
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