Weird 700R4 issues

[NB-K5]

Hey all. New to the forum. Just picked up an 89 k5. Having some weird tranny problems.
Story on the truck. Sat for about 8 years with a blown head gasket. Replaced the gaskets this past weekend. Motor runs a1.

My tranny seems to work fine. Shifts from 1-2 fine. Once u hit about 40-50 kph it will downshift to first. Hit about 60kph and it shifts back into 2nd. Have tried adjusting tv cable. Pulling the cable lots to get the tv moving. Had the pan off and changed the fluid last night.
Trans doesnt seem to slip at all. Torque converter seems to engage and disengage properly.
Really has me stumped. Fairly new with automatics. Im a heavy truck tech by trade.
Hoping someone might have an idea as to whats happening.
Thanks

 

[Jims86]

Hey all. New to the forum. Just picked up an 89 k5. Having some weird tranny problems.
Story on the truck. Sat for about 8 years with a blown head gasket. Replaced the gaskets this past weekend. Motor runs a1.

My tranny seems to work fine. Shifts from 1-2 fine. Once u hit about 40-50 kph it will downshift to first. Hit about 60kph and it shifts back into 2nd. Have tried adjusting tv cable. Pulling the cable lots to get the tv moving. Had the pan off and changed the fluid last night.
Trans doesnt seem to slip at all. Torque converter seems to engage and disengage properly.
Really has me stumped. Fairly new with automatics. Im a heavy truck tech by trade.
Hoping someone might have an idea as to whats happening.
Thanks

adjusting the TV is mainly alter line pressure, but will also move the shift points around Very minimally, because line pressure is a determining factor for shifting.
The proper way to adjust the TV is to push the casing all the way back into the bracket, then manually rotate the throttle to wide open, letting the cable ratchet out. You can adjust it a little tighter, but not too much, as you could blow some seals if there is too much pressure. On the back of the trans, onthe drivers side there is a domed dust cover, under that is the governor. Pry the cap off, and slide the governor out to inspect its driven gear, and make sure everything is moving freely.

 

[NB-K5]

okay.
Will check the governor and see if i can readjust the cable tomorrow after work.
Hopefully it'll solve the problem.
Thanks

 

[Jims86]

okay.
Will check the governor and see if i can readjust the cable tomorrow after work.
Hopefully it'll solve the problem.
Thanks

Yeah, once you get that cable adjusted, leave it withing a few clicks of that base setting, NEVER looser than full throttle. HOtRodPC is the resident mad scientist when it comes to transmissions.
Alberta, Eh? what part? I know some folks in Division 6.

 

[NB-K5]

Im in Calgary. Moved out here last winter from the Maritimes! Nice country out here though and they dont salt the roads!

 

[Jims86]

Im in Calgary. Moved out here last winter from the Maritimes! Nice country out here though and they dont salt the roads!

Ahh, dist.6! I know a few camera guys that were on the Heartland shoots down around Millarville. Lotsa square Chevys on that program!

 

[NB-K5]

yea i saw quite a few on that program! See quite a few everyday some in good shape most could use some paintwork though. They're tough trucks.

 

[89Suburban]

Glad to hear you didn't have cracked heads. Welcome aboard.

 

[NB-K5]

thanks! next time i do a set of head gaskets on a lifted one im going to pull the motor right out. would of made it so much easier!

 

[NB-K5]

So i pulled the governor out last night. Plunger moved fine and nylon gear was in good shape. I removed the entire valve body and cleaned each valve one by one. Reinstalled with new filter and fluid and the problem persists. Think i need a rebuild?