Massive pressure loss when hot

[firebird672002]

I have decent pressures and pressure rise with throttle application when the trans is cold. After about 15 minutes of highway driving, the pressure starts to fluctuate and drop. Clutches start to slip with acceleration. For example, at part throttle cruise, I'm seeing 150psi cold. After warm up its maybe 100. At cold wide open throttle 4-3 downshift I see a fluctuating needle but 230-240 psi. After warm up i see WOT pressure rise barely from 100 to 130. So I drive home and take some hot pressure readings and here they are-
NO TV / FULL TV
P 100 100
R 60 60
N 95 95
OD 70 60
D 70 60
2 70 60
1 50 50
Also when pulling the TV cable out the pressure rises slightly then drops back down. As you can see full TV actually lower than no tv. I have removed valve body and checked TV valve and other valves for smooth operation. I have checked the TV boost valve and PR spring and TCC valve. The trans did overheat from the slipping and the band is cooked. It is going to be rebuilt I am just trying to determine a cause so I know what to look for. Its a Extreme Automatics Stage II with less than 10,000 street miles. Never raced. Any thoughts? Thanks for your time

 

[Phoneguy]

As far as I know Lonnie does refreshes for like $350.00 on his trannies. Give him a call

Bryan

 

[firebird672002]

Thanks for the tip. Any ides what the problem might be?

 

[S10xGN]

I have decent pressures and pressure rise with throttle application when the trans is cold. After about 15 minutes of highway driving, the pressure starts to fluctuate and drop. Clutches start to slip with acceleration. For example, at part throttle cruise, I'm seeing 150psi cold. After warm up its maybe 100. At cold wide open throttle 4-3 downshift I see a fluctuating needle but 230-240 psi. After warm up i see WOT pressure rise barely from 100 to 130. So I drive home and take some hot pressure readings and here they are-
NO TV / FULL TV
P 100 100
R 60 60
N 95 95
OD 70 60
D 70 60
2 70 60
1 50 50
Also when pulling the TV cable out the pressure rises slightly then drops back down. As you can see full TV actually lower than no tv. I have removed valve body and checked TV valve and other valves for smooth operation. I have checked the TV boost valve and PR spring and TCC valve. The trans did overheat from the slipping and the band is cooked. It is going to be rebuilt I am just trying to determine a cause so I know what to look for. Its a Extreme Automatics Stage II with less than 10,000 street miles. Never raced. Any thoughts? Thanks for your time

Guessing if you've had it torn down that far, you have checked/changed the filter and degunked the pan?

 

[TexasT]

Sounds like you have a seal problem. There are many in the trans. I'd pull it and get the $350 refresh. Just not worth goofing around when you have a warranty that has always been made good on from what I have read.

Posted from the TurboBuick.Com mobile app

 

[GBGN1]

Sounds like pump problem

 

[GBGN1]

Drop pressure regulator out of pump and inspect. Also make sure tv valve is free.