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-   -   700R4 Pressure (http://www.hotrodders.com/forum/700r4-pressure-226295.html)

Edgar86 11-20-2012 07:56 AM

700R4 Pressure
 
Hi All,

I have a 700r4 in my GMC Jimmy 6.2 Diesel. It has a transmission that was "GM Certified" rebuilt...it has burned the 3-4 clutches twice. The TV cable is adjusted correctly; however pressure is a constant 120 PSI in all forward gears and over 200 PSI in reverse (my gauge only goes to 200). Pressure does not change when the TV cable is pulled or when the engine is accelerated. Any ideas? I'm thinking it's a stuck boost valve? Both times the clutches burned the transmission was under a heavy load...hauling a trailer and when engaged in 4WD while in snow.

C-10 11-20-2012 10:29 PM

Usually no 'line rise' (pressure) would indicate a stuck throttle valve..

Crosley 11-21-2012 10:44 AM

Quote:

Originally Posted by Edgar86 (Post 1613590)
Hi All,

I have a 700r4 in my GMC Jimmy 6.2 Diesel. It has a transmission that was "GM Certified" rebuilt...it has burned the 3-4 clutches twice. The TV cable is adjusted correctly; however pressure is a constant 120 PSI in all forward gears and over 200 PSI in reverse (my gauge only goes to 200). Pressure does not change when the TV cable is pulled or when the engine is accelerated. Any ideas? I'm thinking it's a stuck boost valve? Both times the clutches burned the transmission was under a heavy load...hauling a trailer and when engaged in 4WD while in snow.

as mentioned , look at the inner TV valve on the valve body. It may be stuck or worn out and goes to OEM max line at engine start up.

Since you have higher psi in reverse , that indicates the 2nd boost valve is operating

look at sizes of the boost valves too. You are replacing parts and not fixing the problem as you have now discovered

Edgar86 11-21-2012 01:50 PM

Thank you for your replies. I will hopefully be digging into the transmission this weekend. I'll be sure to check all valves and look for leaks...I don't want to be changing out 3-4 clutches every couple of thousand miles!!


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