1989 trans wont shift out of 1st?

my friend just recently bought a 1989 chevy 1500 cheyane 4x4 305. he bought it 2weeks ago with a bad trans. the trans would slip when it got hot. it only would work when cold. so we trailered it back to town the guy gave us a trans that was rebuilt out of another truck that moved and ran from his uncle that died. so we took the old trans out and swaped them now the trans wont shift out of 1st. what could cause this? i dont know what type of trans this is but the fluid is a little bit over the fill line and i told him that could cause it not to shift, but he dont beleave me. it this trans run by electronics or vaccum? i dont know but i think the trans they got out of the other truck was a little bit older by a couple years.

You have a modulater valve on the back of the transmission. The line was most likely not reconnected or the modulater valve is bad. Its a cheap and easy place to start

Don

A bad vacuum modulator wont cause the problem you are having. A sticky shift valve or a sticky governor will. I would pop the governor cover off and check it first. These transmissions also had issues with the governor gear breaking inside the trans.


transman

my friend just recently bought a 1989 chevy 1500 cheyane 4x4 305. he bought it 2weeks ago with a bad trans. the trans would slip when it got hot. it only would work when cold. so we trailered it back to town the guy gave us a trans that was rebuilt out of another truck that moved and ran from his uncle that died. so we took the old trans out and swaped them now the trans wont shift out of 1st. what could cause this? i dont know what type of trans this is but the fluid is a little bit over the fill line and i told him that could cause it not to shift, but he dont beleave me. it this trans run by electronics or vaccum? i dont know but i think the trans they got out of the other truck was a little bit older by a couple years.



the problem I have seen is the shift cable that goes from the throttle to the transmission is stuck ...pull on the cable end and make sure it is free moving...

you will have 1st and reverse...if stuck but no upshifting ..

fluid should be sucked out using a hand pump and a long 3/8 plastic line inserted into the fill/stick tube...if overfilled air bubbles will damage the transmission...

thats what i told them it is bad to over fill a trans. the trans pan has a drain plug on it so i will tell them to drain it. too much fluid could be causing that govener not to work right either im guessing. they dont beleive me when i told them that stuff cause when something breaks i tell them the possiblities of what could be wrong. and tell them try this, replace that, thats all a mechanic does when he works on a car anyways.

No, too much fluid will not affect the governor. These transmissions had issues with the governor gear breaking which in turn would keep the governor from spinning. I would pop the governor cover off and remove the governor (It just slides out). Turn it upside down with the gear straight up then with your other hand, push the weights in and release. While you are doing this, watch the governor valve in the center. Make sure it is moving freely. If its not, then the governor will need to come apart and be cleaned real good. If it still sticks, then replace it. Check the gear real good, it is plastic and they crack and break quite commonly. Hold the governor and try to twist the gear on the governor shaft. If it moves then replace the gear. Make sure you get the proper gear. The fluid level is very important. It must not be over or underfilled. Make sure you check the level with the trans hot, vehicle on a level surface and the gear selector in "P". As far as the TV cable goes, if it is stuck in full TV, it will still shift but it would shift very late and in high RPM's (for first gear that is).


transman