Thread: Toasted Tranny in my '98 GT

Daughter #2 has the '98 away at college, and she complained of the trans slipping a little when cold, but OK once warmed up. I looked at it 2 weeks ago, no leaks, fluid full to top and clean pink color, and drove fine.

Last week the front seal blew on the highway. Catastrophic fluid loss produced lots of smoke and promopted a shut down before the CEL ever came on.

Diagnosis from the rebuilder is that every non-metal part inside melted. Even rubber parts melted. TC got so hot it was blue. Total cost out the door will be $2300, but includes new computer, all new sensors, solenoids, clutches, bands, etc. basically everything inside the case. Not an expert on this but am told will have some "better" aftermarket parts that address OEM weaknesses.

Still trying to figure out why the front seal blew, even the rebuilder says that is not common on these cars. Any comments welcome.

Originally Posted by Sabrewings

What front seal?

The seal between the trans and motor, as I understand it...

Again, I'm far from knowledgeable on the details of these things....the trans guy did say it got so hot that the rubber O ring on the input shaft melted. Whatever seal failed, it was not a slow leak, it basically dumped the fluid so fast that the trans baked before the CEL could come on. Temps rose so fast that even teflon thrust washers were melted into blobs.

In terms of timing, my daughter called from the highway to tell me the trans was "shifting funny", and asked me to make an appt with our local mechanic over the Thanksgiving holiday. I called him, and he said it sounded like the fluid was low, call her back and tell her to stop at the next exit and have a gas station add fluid. Before I could dial the number, she calls back to tell me she's on the side of the road and forward motion was no longer possible, smoking like it's on fire.

So, less than 10 mins from cruising to toast. Trans guy said she was lucky it didn't catch fire.

I'm trying to figure out what failed to cause it to get so bad so fast.

I thought there would be an overtemp lite or at the very least the CEL would come on to indicate overtemp before it got hot enough to melt itself. I guess this is why Rick Waggoner was in front of congress on his knees looking for $25B.....

Originally Posted by Sabrewings

I think you'd know if your tranny was burning up.

Well, that's the issue....by the time it became apparent that the tranny was burning up it was already toasted. Kind of like grabbing something HOT...you yell O-S**t and drop it as soon as you realize it's too hot, but it's too late, you've already burnt your hand.

I have never heard of a tranny going from zero-to-toast in under 10 mins, and I'm trying to figure out what may have happened to cause that.

The 4L80E on my truck has a temp gauge so I can stay ahead of any problems when I'm towing.

Trannyman, thanks for the info!!

Yes, the fluid that came out looked like you could patch a road with it! Unfortunately, the shop is 2 hrs from home, and I didn't get to see the trans fully apart and out of the car.

Bear with me while I try to remember what the trans guy said, but his diagnosis was something to the effect that there is a solenoid or some sort of valve that controls fluid flow to the cooler. On cold start up, onlt half the fluid is sent to the cooler to promote warm up, then once up to op temp, 100% of fluid flow to cooler is enabled. This thingy got stuck closed, or otherwise failed to operate, and kept the cooler flow restricted even after the trans reached op temp. The trans guy wasn't sure what would make the front seal blow, but your explanation makes sense.

What amazes me is that my daughter was only on the hiway for about 20 mins, gives you an idea of how fast heat builds in these things. Trans guy said this was actually a blessing.....on disassembly, he said the chains were so loose that they were about ready to let go, which would have destroyed the entire case and everything. Only 117K miles on this car.

So, I'm looking at $2100 out the door (plus tax, so closer to $2300) with basically all new parts and electronics and a 24 month 24K miles guarantee. At this point, the cooler looks to be OK, but will be flushed and checked.

Although I have no prior experience with this trans guy, he is a professional rebuilder, says he uses only the best parts, and very rarely has a job come back for repair under the 24 month guarantee. The car is due to be ready tomorrow, is there anything that I should be asking or checking on?

What really worries me is that my other daughter drives an '01 GT with 118K miles on it....is there any preventative maintenance I can do on the trans besides a fluid/filter change that will hedge my bet on the trans lasting longer?

Would it be cheaper to take it out and rebuild it before it fails?

I have a 2001 with 120,xxx miles on it & I lost the 4th gear clutch hub and lost 4th gear entirely. The splines on the end are not heat treated in the 01's and will eventually strip out costing you 4th gear. Mine allowed the stripped metal bits into my valvebody and throughout the tranny, so a rebuild was required. You can get to the hub with the tranny still hooked to the engine - it's behind the channel plate. Would be cheap insurance to replace that before it grenades and takes the tranny with it.

sounds like a good deal, it sounds like he is replacing everything that would be considered an update, ie: the 4th gear hub. figure 500$ of that 2300 goes to the removal and replacement of the trans itself

Originally Posted by Sabrewings

Without lubrication bearings heat up fast. And at highway speeds things are spinning pretty quickly. Ever seen what happens to an engine if you pull the drain plug with it running. If you ever have an old engine sitting around, try it. Some parts on the outside will start to glow from the heat around the bearings and eventually the moving parts will expand enough from the heat to seize it up and weld them together.

Never thought about it like that, but that's about right. My cash is draining from my wallet in direct proportion to how fast the fluid drained from that trans....