I had my 4T65E overhauled at a local tranny shop, including all the usual suspects replacements, plus a new sun gear, and an aftermarket "new" torque converter. Drove it past the 100,000 km (yeah it'* metric here in Canada) warranty by about 10,000. Also beyond 1 year of warranty.

Always ran Dexron VI in it, even though it originally spec'd to Dexron III. Tranny guy said it was just fine: Dexron VI was essentially new and improved Dexron III.

Driving car on 300 mile road trip at highway speed. Starts to lag shifting out of 2nd and doesn't want to stay in Drive/3rd unless I baby accelerator. Slightest depression of pedal or slight grade requiring tiny depression of pedal, jumps back down to 2nd. Did pull over and check fluid level. Perfect, right at full line. Car not overheating.I have had such problems with trannies in prior years, and have gotten a lot of mileage out of them before mega-failure, so decide to keep going on trip in hopes of making it. Go about another 100 miles. In the mountains, so decide to put car in neutral wherever gravity will assist my travel, and move it into drive when road flattens out again.

Then, suddenly, massive loss of tranny fluid, and major smoking of car. I immediately pulled it over. Oil draining out on ground. Leave car there and hitchhike into town. Come back next day with U-haul dolley. Start car and drive it up onto dolley about 20 feet of forward movement and then immediately shut it off. Causes spill of oil. Oil all over dolley. Drive car off dolly another 20 feet, and there it stayed, sitting for 2 years. Recently, a mechanic friend helped me pull the tranny. Claims he checked the stick and saw oil level in range (between fill and full), although did it cold. No sign whatsoever of residual oil on case etc. I had left the car "unwinterized" when I parked it, and the block had frozen. The block heater was laying on the ground, the radiator almost empty, and water in the engine crankcase..

My friend had recommended the transmission shop that did the rebuild . He knows it had been fully rebuilt not long before the problem and less than 65,000 miles of successful trouble free operation until the problem. We didn't clue in that the engine block/radiator had frozen, so my friend assumes the block heater fell out of the block during the road-trip, suddenly spewing steam, which I mistook for smoke. Is very confident about transmission given the foregoing, says it must be something else that leaked, such as coolant, and transmission must be fine. It had been 2 years and I began to doubt my memory of red oil on dolley and roadside, and the acrid smell of smoke instead of the sweet smell of antifreeze steam.

Obvious after-market torque converter visisble (so was replaced during rebuild): painted blue. Cooling lines perfectly intact. No signs of oil, in fact because transmission had been cleaned and painted silver, it still looked really nice/new, like a rebuild.

Just put the transmission in another car on the strength of these observations assertions. Car went around the block with no problem with my friend the mechanic test driving it. Then I took off for home. Stopped a store on the way a few miles away. Almost slipped and fell in the tranny oil river that was running out from under the car within seconds of me parking.

Had extra oil so added it and tried to make it back to my friends. Made it, leaving a visible trail of oil on the pavement all the way. Car proceeded to leak a small lake under it after parked it at my friends. Hasn't been started since.

Can anyone who knows about transmissions tell me where the oil would be leaking from? Must it be coming from the torque convert to spline shaft connection/seal? It does not seem to be coming out of the CV shaft seals.

Moreover, if the car wasn't leaking, but started to not want to go into or stay in 3rd gear/drive, and then 100 miles later has a major sudden oil profuse oil loss, is this consistent with a failed torque converter? Or does that mean there'* likely some other kind of internal problem that might have caused a pressure spike, leading to a secondary issue of a seal blowing, and I in fact have problems internal to the transmission, not likely the torque converter?

Your thoughts would be appreciated. I ask because I can easily swap the torque converter, but don't want to bother if after I do so, it'* just gonna be gushing out oil again.

I have two other used T465E transmissions, one of that came out of the car that the leaking one is now in, and which seemed tired, because while it shifted like a dream, it would shudder hard if I did not baby it on taking off (worn bands/clutches I think). The other is an "as is" pull from the autowrecker from a 1998 car.

I am thinking I will put the auto wrecker tranny into the car and cross my fingers, because the one that'* in it now is leaking like a sieve, and the one that came out of it, while it worked sensibly, was clearly tired.

Should I just put one of the old torque converters on the one in the car and see what happens? This is where an expert opinion would be very helpful. Or would you recommend I consider the leaking transmission "blown" and get rid of it, and take my chances with the auto-wrecker transmission?

Thanks a bunch.

It would be best to figure our where on the outside of the transmission the fluid is coming from when it leaks. Without that, we'd all be guessing.

I won't be going to the location of the car until the weekend. I will try jacking it up to see if I can tell where the oil is originating on the transmission, although like I said, when we pulled it after it sat for 2 years there wasn't so much as a tiny trace of oil visible on the outside of it or in the bell housing below the converter (although didn't remove the converter).

The key aside from the location of the oil leak is the behavior I described about it not wanting to stay in Drive, but rather jump back down to 2nd, which happened for the hour plus of highway driving prior to the sudden dramatic explosion of oil leaking.

Is that behavior consistent with a failed/failing torque converter, even if it could be caused by something else? What I am saying is that it isn't necessarily just a straightforward blown seal/leak, because there was the odd behavior preceding the catastrophic/sudden leak. And as noted, I pulled over and checked the stick and it was perfect. That was about 50 miles after I noticed the odd behavior, and so there was apparently no leak then. It was only after about another 50 miles of travel that something suddenly blew.

I can only think of the CV shaft seals or Converter to spline shaft seal (aside from something unlikely like a housing or pan gasket, and all looked intact when we pulled it out).

I don't think a sudden blow out of a CV seal would be preceded by an hour plus of highway travel with strange shifting problems.

Theoretically, doesn't this just leave the Converter as the suspect, or could my concern that something inside the unit started failing, which eventually led to such a tremendous pressure spike that an otherwise good seal blew out?

I will endeavor to see if I can find out where the leak is from this weekend, but by logic and process of elimination of the facts, is there any opinion on this if you are a transmission guy?

Cheers

It sounds like the transaxle is toast anyways. Regardless, we can get nowhere if we don't know where the leak is coming from.

This tells me something internal has gone bad or gotten plugged up or something.

No, if the torque converter is failing it would do other things and make bad noises and maybe set codes about slippage. You're talking ratio delivery in the transaxle. For what it'* worth, I've never heard of a torque converter just up and failing in one of these, even when well beaten . . . let alone when new-ish.

This sounds like internal issues, not TC.

Maybe something overpressure? Maybe a bad pressure regulator? We're still guessing. Either way, probably not TC.

. . . or the electrical connector, or the cooler lines. Either way, the cause would be internal and severe and almost unheard of and not the TC.

Why not? Maybe some junk lodged the pressure regulator wide-open and caused both. Maybe pressure was gradually building and the shifting problem happened at a lower overpressure than the dumping of oil. Or etc. etc. we're all guessing.

Theoretically no. Pressure may not be related either.

Good first step.

If I were a transmission guy and my customer brought me this list of symptoms, I'd recommend a complete overhaul. The TC isn't likely, and the symptoms are extreme and unusual with no known external contributing factors (jumping, racing, damage, towing, abuse) . The alternative would be that I charge the customer hourly for removal, disassembly, and diagnosis, and the hourly rate would end up costing more than an overhaul and probably not fix the issue. With my reputation on the line as a transmission guy, I'd opt to lose the business if the customer didn't want the overhaul versus getting the hourly rate to diagnose forever, not fix it, then take the chance that the customer might say bad things about my abilities when we are $3,000.00-hourly into a transmission that'* $2,000.00 to overhaul and we still don't know what'* causing the problem . . . or when we are $1,000.00-hourly into it and determine that a $2,000.00 overhaul is necessary for a total of $3,000.00 spent on a $2,000.00 transaxle. All for a $2,000.00 car.

Remember, almost all diagnosis and repair of a 4T65 (especially with your symptoms) involves disassembly, and almost all disassembly of a 4T65 involves removal from the vehicle. A couple of ins and outs and you may as well have overhauled it. It adds up.

Thanks for the excellent comments. I suspect based on my intuition and your comments, that a new aftermarket TC with only about 50,000 miles on it (max), is not the problem. It'* just that I'm rebuilding the motor, and because it'* out, and I have 2 other TCs, it would take all of 30 seconds to swap the TC. But then, to reassemble everything and still have the problem, when I can easily swap out the transmission with another I have as the motor is out, probably would be the worst possible outcome.

I will just try putting in another transmission of the 2 spares I have and see what happens. I will update the results for interest.

I cannot afford (yet another!) transmission overhaul because I have just sunk thousands into the engine rebuild, and if and when I do a rebuild, it will not be on this fouled transmission; it will be on whichever one of the two spares I have that doesn't go in in the next few days.

For the meanwhile, I need a working car. I have a tired (shuddering under all but modest acceleration) transmission that came out of the car recently, and an "as is" pulled from an auto wrecker car. I think I will put the auto wrecker one in, and cross my fingers.

Thanks again.

I'll cross my fingers too.

UPDATE: I put the auto wrecker transmission in and knock-on-wood, it seems excellent. Really excellent. No slips, even under power take-off. Pan was cleaner than my so-called recently rebuilt (2016) 4T65E! As noted above, it was puking oil out like crazy. It only got about 5 miles of driving on it since new filter and new oil was added. So, pan coming off auto-wrecker as-is pull tranny had less sediment in the pan than the one that only went 5 miles on clean oil and filter! To be sure, both were very clean, but the auto-wrecker one was cleaner. I may have just lucked out it looks like!

Oh, one weird thing.

I had 3 transmissions:

1. Auto-wrecker pull tranny (looking now like a gem!)
2. 2016 rebuild from retired car (failed on that car'* last trip to storage)
3. Tranny that was in the replacement car when I bought it (tired and slipping, but still functioning)

Here'* the weird thing: they all came from 1998 Oldsmobile Intrigues; they are all 4T65E trannies. Because I had just put a new filter in the #2 tranny and had only driven 5 miles on it, when we pulled it from the car, I was planning to put the filter out of it into the auto-wrecker tranny that was going to go into the car. Also, at some point, someone had apparently used a punch or hydraulic punch on the pan on the auto-wrecker tranny to create a de-facto drain hole in it. The pan was not otherwise distorted in anyway, except that in the center of it, a hole a bout the size of a pencil had been made, and metal was folded upward in the process of the hole being made.(folded only at the hole, no distortion anywhere else on the pan, which seems to indicate it was done by a special machine, perhaps at the factory?). Then, after removing the pan, there is a rubber cap on top of the folded-up metal, inside the pan, to prevent any leaks. It didn't look in good condition (rubber was sort of tired looking), so I decided I would swap the pan from the other tranny onto it, as well as the filter.

Pans on all 3 trannies the same shape and size when laid beside each other. Same number of bolts for each pan; all 10mm heads.

Here is the weird thing: the size of the holes in the auto-wrecker tranny pan are smaller than the other two transmission, which incidentally have the same size holes among them. While the heads on the bolts in the other two transmissions are the same size as the auto-wrecker tranny bolts (10mm), they are considerably larger diameter threaded shafts. In fact, the bolts from the auto-wrecker tranny will just push in the other two trannies until they bottom out, without resistance to the finger. I'm thinking the bots on the #2 and #3 tranny in the list above are about 1.5 x larger diameter shafts.

These transmissions have reusable pan gaskets with metal inserts on the bolt holes, and rubber between. The gasket on the auto-wrecker tranny has correspondingly smaller metal inserts and correspondingly smaller holes in the gasket. In other words, if I laid the gasket from the auto wrecker tranny on either of the two other pans, the holes would line up, but the bolts for those transmission pans could not pass through the smaller gasket holes.

What the heck? I had to therefore use the "compromised" pan on the auto-wrecker tranny and could not swap it with the pans from either of the other two trannies (which incidentally would interchange no problem between those two, and incidentally are the same overall shape/size as the auto-wrecker tranny pan, with the holes in the same location on all three pans, except that only the auto-wrecker tranny has the small diameter shafted bolts).

Anyone surprised by this or encounter this issue before? It seems irrelevant, as the auto-wrecker tranny is now in the car and communicating perfectly with the PCM, etc, and working well. And it for sure came of a 1998 Oldsmobile Intrigue, like the other two trannies I have.

BTW, the 2016 rebuild failure tranny has now gone to the scapyard. I have the tranny #3 in the list above, and I was originally planning to rebuild it while the auto-wrecker tranny got me around for the next year or so, but because the auto-wrecker tranny is so tight and flawless, i think I'm just going to scrap it too, and not do a tranny rebuild at all. I spent $1650 on a rebuild in 2016, and it failed miserably; I've kind of lost my faith, and the auto-wrecker one is now approaching 500 miles and is working spectacularly.

LMK if anyone has any comments about the weird bolt issue. I would have liked to have swapped that punched pan with one of the other two, but couldn't!

Great news on the junkyard transmission working so well!

Not sure what to think about the bolt size etc.

GM changed bolt sizes for the pan. So you need to get the correct version

ACDelco 24206181 GM Original Equipment Automatic Transmission Fluid Pan 2nd Design

W/TRANS UPDATE LEVEL 02 OR GREATER,


1ST design See part 24207558