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Help 700r4 locks up in 2nd.

Kjunky5

Kjunky5

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Just rebuilt a 700r4 for my DD. Heres the problem. When the fluid is warm it shifts like a dream but when it's cold, like first thing in the morning, the TCC locks up in 2nd and stays locked through all the gears. Even with NO power going to the solenoid. As the fluid begins to warm up, it gets better. For example. If I'm easy on the gas it unlocks, but when I give it gas and the rpms increase, it locks back. I know that has an affect on the pump speed. My question is could the TCC valve be installed backwards cause this? Could there really be enough dirt in the TCC solenoid to cause fluid to back up and build enough pressure to lock the TCC? This is driving me nuts. :angry1: Obviously cold fluid has a lower viscosity than hot fluid. I'm afraid the sun shell is going to go snap again if I don't fix this soon. Being locked through all the gears has to put alot of shock through the trans. I don't have a pressure gauge. The trans is a 1991 model. You guys have got to help me!!!!
 
FWIW my 89 blazer trans the convertor will lock in 2nd, 3rd, and 4th. Most of the 700's this is normal.
 
I wish I could help, but you are much better at transmissions than I am. :dunno:

This trans was just rebuilt if that puts a lightbulb over anyone's head.

Hope you get it figured out.
 
BGKYK5 said:
I wish I could help, but you are much better at transmissions than I am. :dunno:

This trans was just rebuilt if that puts a lightbulb over anyone's head.

Hope you get it figured out.
Click to expand...
Thanks man. Like I said, it shifts like a dream when it's warm. It's just having to put up with this problem until it's warm.

BTW this is off topic but if you get tired of that Detroit makin all that racket, just yank that noise maker and send it my way.:D Still in the axle of course.:D
 
To lock the TCC you need pressure from a valve - the solenoid vents that pressure to back to the pan (unless it has current through it). If you get lock up without the solenoid connected then something is plugged. I remember there is some mod where you put a little check-ball on top of the solenoid, but I can't remember why. You might ask the shop about this. If you're lucky, it's just the solenoid, which is easy to work on just by dropping the pan. For troubleshooting, you could pull it right out of the tranny and see if that eliminates all lockup. That also gives you a chance to check it out.
 
Did you use one of those piece of crap aftermarket "universal" TCC's, or did you use a purpose-built 700R-4 one?

I wasn't happy with the universal one I ended up with for my 200 (fits both 200 and 700 supposedly) and with as poorly as it was constructed, I'd have little faith in it's performance either.
 
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