Tranny troubles revisited.

[NewK5Guy]

Been doing some ovservation since you fellas and ladies offered your help. And I've definetely seen 2 sides to this.
My tranny(84 700r4) is defintely hot natured. My losing lockup and reluctance(more like downright refusal) to unlock happen mostly when the tranny is nice and hot. When it's cold after sitting overnight, let's say, it will drive just fine and usually even unlock from 4th by itself while at steady throttle working an incline. And even SOMETIMES, I can lightly press the accelerator and it will unlock as it should. Today was a good example of working properly. Ambient air temp in the low 60's. On the way home the tranny was very nice to me. But if I pushed it hard and got it hot, it would crouch back in a corner until it cooled off some. I'm now wondering how much impact the large external cooler will have when I install it. I'm picked one out. Just waiting on the funds.
So now the big observation is the fact the tranny won't unlock on command. If I lightly press the gas pedal(remember, this is a diesel) to begin an incline, the converter will not unlock. As I press the gas more to maintain a steady rate of speed, I'll eventually press it down far enough for the downshift to 3rd. Yes it will unlock with the press of the brake pedal, but won't stay unlocked. Even with foot on brake, it will relock.
Any new ideas?

 

[Wheels]

Could be one of three things, Solenoid ground no making contact (external or internal), the convertor clutch apply valve could be stuck, or the convertor itself could be bad. Is the clutch applied at all times? Does it want to bog down the motor when you stop? If not, this may be one of them horky things that a diesel 700 does that can't be helped. There are some differences between a diesel and a gas version that mainly deals with the input shaft and the torque convertor. Since a diesel is slower to respond to gas pedal inputs than a gas engine, the release may not be as noticeable. Mine only drops about 200 to 300 rpm at TCC apply. I wouldn't pull it apart, but I would add the cooler to it since it is having a heat problem. Heat is the number one killer for an automatic tranny.

 

[89Blazin]

Same thing goin on here too. 89 with the 700....we been talkin about this on a couple other posts. 89,90,91's doin it. Slight incline.....no unlock....drop 15 mph....automatic downshift to drive...kind of thing. With cruise on....pedal is being moved ....not fast enough. Steep hill....downshifts almost immediately and no loss of speed.

85 Burb and an 89 Blazer
One just for fun, one simply for pleazer