ok i have a 400 turbo in my work truck and when it is cold it will shift perfect when it warms up it will not shift at all... i have change the modulater and governer same thing happens can or does anyone know what the deal is

 

Couple questions. Have you had the pan down to see what if any debris are in the pan? This could be causing the governor to repeatably stick. Also when you had the governor out, how did the bore look inside the case? I have seen this happen in quite a few 350/400 over the years. When you had the modulator out, did the valve move freely in the case? Also there is a solenoid in the trans for kick down? If the solenoid is stuck it could be making the trans think that it was at a full throttle condition. This would make for late shifts or a no shift situation if you did not totally wind the motor up. Vince

 

no i actually didnt look at it it is in a 88 model 4x4 1500 ... there was some dirt in it i have thaught bout some sea foam to clean it flush it out i dont really know where a solenoid is in it but i will look at it anything else i should look for

 

I have never heard of a sea foam for transmissions. However if that is the original trans in that truck it is 20years old. It is due to be redone. The problem is if the trans is making debris a flush is not going to fix the problem. It will continue to make debris. Drop the pan and do an inspection. If there are debris present replace or rebuild the trans.

 

We had a work truck in our shop last summer. It was similar and drove my mechanic nuts. To cut to the chase we found the relay on the firewall bad. Just another thing to check. Hope this helps. PS, I've never heard fo Sea Foam for the trans, either.

 

sounds to me the tranny is worn out. when the tranny is cold the fluid is thicker if there is a little bit of a clearnce issue in the pump or the seals are leaking the fluid will still be thick enough to seal however when it gets warm it thins out and you get internal leaks. kinda sounds like the clearnces for the valves in the valve body are too much. however it is time for a build. the th400 is tough but it has its time also