I'm having the ever-so-popular "no torque converter lock-up" and "no overdrive" problems. But here'* the thing...it doesn't happen all the time. It happens when the tranny, not the car or the outside air, temps get up up there. So I did what everyone suggests, and got a flush done at a shop - good deal too at $38.90. And I checked with the shop owner that they did use the proper GM reccommended DEXRON equivilant fluid.

Here'* how she drives. EVerything works fine, all gears shift correctly, TC locks up normally. Get the tranny temps up a bit, say some hard accelerations or a few quick blasts down a highway or whatever, and a few minutes later she starts having problems. First thing notcieable is overdrive goes in, but there'* no TC lockup. Give it about a few more minutes at a constant crusie speed of around 65mph, and boom, overdrive gone and still no TC lockup. Now if I let the car sit for say 15-20 minutes after this occurs, she will be fine again, TC lockup and overdrive will work fine.

I'm thinking I could get away with more tranny cooling to keep this from happening so much. It seems that when I'm doing a lot of city driving (like I noticed all this yesterday doing a lot of city driving in the rainy weather @ about 68º outside) she'* just on the verge of having the problems start. I also noticed that when the TC and OD don't work, the tranny shifts very smooth from 1-2 and almost unnoticable from 2-3 under normal city-drving accelerations. I'm thinking there'* a drop a in pressure, which is causing the smoother, lighter shifts. When she'* cold and not having any of the problems going on, the 1-2, 2-3 and 3-4 shifts are very really noticeable and firmer (like they should be).

Plus, when the car was hot yesterday, I checked the new fluid on the dipstick to find that it was a little bubbly on the dipstick. Is this normal? I would have to guess the tranny was running a bit over 200º at that point. If she'* running too hot, would that cause the fluis to bubble, reduce viscosity and therefore cause my pressure drop, which in turn would cause smoother shifts, and not enough pressure perhaps in the torque converter for lockup?

Car and trans have 89.7k on the ticker.

Input please....thanks a million.

Your trans has a feature that doesn't allow the TC from locking up until the Coolant is 130°F. Sounds backwards, but it COULD be related, as it uses a valve to prevent TC lockup. This valve may be shorting at high temps? I dunno. Could be as simple as very little friction material left.

Haven't gotten a SES light at all. As I read most tranny codes won't throw a light. I will scan it when I get back to school next week. We have a Tech II scantool.

It does sortof sound like a TCC failure, but something is odd about how this one is acting. The solonoid shouldn't be THAT sensitive to heat. I agree. Scantool on this one for sure.

How hard of a job is TCC replacement? Isn't there a revised GM part that can replace the bad one if that'* the problem?

Also, what'* up with my "smooth" shifting? I think it'* too coincidental that the smooth shifts (usually realted to pressure drop) occur at the same time frame when the TC and OD crap out. Any thoughts on this part of the issue?

And oh yeah, Tech II owns.

I checked the fluid a couple weeks ago (just got the flush done Wednesday last week) and it looked fine in color, and smelled like 89k tranny fluid. The fluid in there now smells the same, the color is a tad bit better in pinkishness (how'* that for a word ). I think even a couple weeks ago it was a bit aeriated (slight bubbles at hot operating temperature) just like it was the other day with the new fluid.

I've been doing all highway driving this weekend so far, and the tranny has been acting just fine. I haven't been "beating" on it at all and the TC has locked corectly, OD is functioning fine, and the shifts are all quick and noticeable. I have been testing it out drving in NORMAL mode for the weekend so that the shifts wil occur sooner just to make sure OD and lockup is working correctly and so far so good.

I'm thinking there might some issues with cooling still. Not beating on it, and driving down the highway yeilds good tranny behavior. I give her some city traffic for a long time and some bursts down low and she heats up, from what I can assume from the smooth shifts anyways.

Thank God for scantool'*.

Slap another cooler on there for the short-term. It can't hurt, and might help, or at least buy you time while you figure it out. I'm running duals myself.

I was already comtemplating running a larger cooler and possibly adding small electric fans just to that cooler alone to help keep temps down. I think it might be feasible and fairly inexpensive...compared to the cost of transmission repairs.

Maybe my tranny is just overly sensitive to heat. I will attempt further cooling to see what happens. Hopefully it works out with a big benefit. I will be scanning her soon though...that'* the most important step I think at this point.

DJ SHO

The next time your tranny locks out of OD try shutting the car off and restart it and see if you get OD back. Could tell you if it is really a temp problem or not. Shutting off the car resets the computer. If you can narrow down when and how this problem occurs so you can repeat the problem it might help narrow it down. You need to put it on a scan tool for sure. I have an extra 94 computer for a Bonn. I will let go reasonable.

Good luck and keep us posted
Doo700

i just talked to our local tranny expert, and he said it sounds like it could be two things (assuming that your fluid is not discolored, and its at the proper level)

and this was off the top of his head, but he knows his trannies...

1) pump seal off location

2) pwm solenoid leaking

the PWM works with the TCC, and if its leaking, it could affect that.

he asked to keep me posted (he was really curious what would cause the bubbling if the fluid level is correct - usually, the *only* time you see that is if you have too much fluid, and its getting churned up by the internals of the tranny) <- that'* a really bad condition, btw - air bubbles can find their way to the pump and cause cavitation, and your tranny'* lifetime just dropped down like mad.

anyhew, let us know what you get off the tech II - i hope to own one of those some day