Leaking th400... Overheating?

[bucket]

We took the '86 Burb down south over this last week and it developed an issue on the trip back home. Coming up 77, we got stuck in a couple LONG traffic jams and it was pretty hot out. Finally got out of traffic for a bit, then the truck started smoking like a freight train when we were pulling a long steep hill.

When we stopped, there was tranny fluid all under the passenger side of the truck, and all over the right exhaust (smoke). The fluid had been leaking out of the right side of the tranny, but the leak had went away by the time we got stopped. It looked like it had come out of the case vent tube, but the vent tube itself looked fairly dry. Checked the fluid level and it was just a bit low and it looked dirty and smelled kinda burnt. Although it has always looked dirty since we got the truck (but didn't smell funny).

Let everything cool down a bit and then got back on the road, but kept the speeds to 65mph or lower. Sure enough, a little bit later the truck started smoking while pulling a hill. Same thing as last time... fluid all under the truck, but not leaking by the time we got stopped. Let it cool down again, and it was fine after that.

What the heck is happening. Did the tranny simply overheat and fluid came out the vent? It shifted fine the whole time. I know a fluid/filter change is in order.

 

[crazy4offroad]

I was down 64/77 way this weekend and there was a god awful dead deer beside the highway near Beckley, maybe the trans just got sick and had to purge a little? My cousin did the same thing but had to pull over first haha. But seriously was it overfilled? I'm not familiar with trans fluid, does it expand when overheated? Might wanna look into an add-on trans cooler. HRPC will be the man with the answers on this one.

 

[89Suburban]

Doesn't sound good to me whatever the problem is. You say only did it on hills. So what type of throttle load and what gear does it do it?

 

[bucket]

I was down 64/77 way this weekend and there was a god awful dead deer beside the highway near Beckley, maybe the trans just got sick and had to purge a little? My cousin did the same thing but had to pull over first haha. But seriously was it overfilled? I'm not familiar with trans fluid, does it expand when overheated? Might wanna look into an add-on trans cooler. HRPC will be the man with the answers on this one.

We were passing through Beckley on Sat afternoon... I don't remember a stinky deer though, lol. It's not overfilled and there is no add-on cooler, there's no room behind the grill because of the aux fan and the oil cooler. I was thinking about getting a cooler/fan unit and mounting it under the truck, on the frame rail.

Doesn't sound good to me whatever the problem is. You say only did it on hills. So what type of throttle load and what gear does it do it?

Yeah, only on hills. I was pulling the trailer loaded with a stepside bed, a car roof, and four car doors. Because of all the weight, I was usually on the throttle pretty good but IIRC it would never have to downshift to 2nd.