Shiftless (sometimes) turbo 400

[cornemuse]

My '84 6.2 Blazer with the Turbo 400 has recently begun to not wanting to upshift when cold. Yesterday, I thought the motor was gonna explode before it finally shifted. As soon as it gets a little warmed up, it is no longer an issue.

Originally, it had a 700 r4, but the previous owner (he bought it new) replaced it with the T 400. He did a lot of towing & replaced several 700's before a shop swapped trannys.

The electric wachamacallit on the fuel governer is still connected th the cars wiring, lays under the intake manifold/governer. It has the vacuum reg installed, (duh) and replaced about 5 years ago. Trans rebuilt about 10 years ago.

Yes, I checked, the trans fluid level is ok.

Ideas?

-corne-

 

[3500GMC]

Try disconnecting the single kick down wire on the left side of the trans, to the rear, above the pan rail.

If it helps, the electrical switch deal is sending voltage continuously and could be damaged or out of adjustment.

There is also a way to adjust the variable vacuum switch, much like a TPS only with vacuum, on the pass. side of IP.

 

[billyg38120]

No upshift cold 400

My '84 6.2 Blazer with the Turbo 400 has recently begun to not wanting to upshift when cold. Yesterday, I thought the motor was gonna explode before it finally shifted. As soon as it gets a little warmed up, it is no longer an issue.

Originally, it had a 700 r4, but the previous owner (he bought it new) replaced it with the T 400. He did a lot of towing & replaced several 700's before a shop swapped trannys.

The electric wachamacallit on the fuel governer is still connected th the cars wiring, lays under the intake manifold/governer. It has the vacuum reg installed, (duh) and replaced about 5 years ago. Trans rebuilt about 10 years ago.

Yes, I checked, the trans fluid level is ok.

Ideas?

-corne-

I assume you have tried to change or inspect the filter seal in the pump neck and are ok not hard and brittle.
This was a common problem with 400's back in the 70's and 80's. If the electrical disconnect didn't help, it usually is the clutch seals are getting aged and hard. Unfortunately it takes an overhaul to correct it. Many kits are ava. Transtar is about the best all round, I feel. If you are not a drag racer and don't drag race the trans, don't waste you funds on these hi end clutches. Don't buy the Kolene steels either. Use the dycro Or Sealed Power filter or the non screen one. These expensive parts are just not worth it for a daily driver. Put your funds in a good reman converter. Dacco.
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