Transmission mystery

[firefighterbri]

I was pulling my 34' travel trailer going @ 75mph when all the sudden my speed started decreesing and my tach started increasing. I got it to the side of the hiway and fluid was just running out from under the truck. two hours later when I got the truck and trailer towed to the nearest service center, they poured new fluid into the trany and found no leaks just a wet underside. the drove it around for an hour and still no leaks. as a last resort put a dye in it an only slight leakage around the pan bolts. we decided to do a flush and change the filters and pan gasket. I bought a gallon of fluid and a funnel and continued the trip. I pulled an additional 300 miles with the tailer drove around for the week end 10 miles or so and pulled back home 400 miles and no leaks yet. What could have happend? and wha should I do for piece of mind so I don't get stranded again like this in the future. I don't know if it matters but I have 110,000 miles on the truck

[Brian]

did you check the fluid level recently before that event? curious if it was overfilled, may have foamed up. not a tranny expert though.

[firefighterbri]

I checked it maybe a month prior when I changed the engine oil and it was in the safe range when hot. since I've owned the truck I haven't noticed any leakage from anything. this seemed to be out of the blue so to speak and the truck has performed perfectly and almost better than before the event happend.

[Brian]

check back in a couple of hours, there are a few guys on this site that will be able to provide you with some great educated guesses, and welcome to the forum!

brian

[mschn99]

sounds like you overheated your trans, which also would have caused some slippage. were you towing with the tow haul button engaged.......and do you have a trans temp gauge to monitor what you were running???

regardless, if you tow a decent load, i would highly reccomend and additional external trans cooler to help keep that fluid temp down........Marc

[firefighterbri]

I have a trans temp gauge and it didn't get above normal. I didn't have the overdrive switched off which I normally don't. once I noticed that I was having trouble mainaining speed I did switch the OD off. The service tech said that was the same as down shifting at speed and may have overpressurized the system and possibly blowing a seal out. He also said it was possible that the seal cooled and reseated itself and stopped leaking. Is that possible? O and yes it does have a trans cooler factory.

[mschn99]

Originally Posted by firefighterbri

I have a trans temp gauge and it didn't get above normal. I didn't have the overdrive switched off which I normally don't. once I noticed that I was having trouble mainaining speed I did switch the OD off. The service tech said that was the same as down shifting at speed and may have overpressurized the system and possibly blowing a seal out. He also said it was possible that the seal cooled and reseated itself and stopped leaking. Is that possible? O and yes it does have a trans cooler factory.

i would still invest in an additional cooler while towing..........

but as far as the temp goes, the od cancel should be used at all times while towing any kind of a load. the slippage creates a lot of heat, and that heat is directly transfered to the seal he was referring to, since that is actually the seal that rides on the torque converter where it goes into the trannie. if the temp at the convereter was high, but the rest of the fluid wasnt being overheated, it is possible to have an overheat without the hot fluid ever hitting the sending unit for your gauge. watch that trans close, because while the seal can reseal itself (yes, that happens frequently), the converter may have suffered damage. if you feel anything out of the ordinary, like a little surger or stutter while towing at a constant speed, i would get that converter replaced. that is the weakest link in the trannie, and that is usually where bigger problems start.......Marc

[firefighterbri]

thank you. that makes perfect sense. I was alway under the impression that unless the transmission was shifing in and out of OD to just leave it in OD. If it was doing alot of shifting then lock it out, into tow mode so to speak. I have been towing like this for with my last three trucks for the last eight years and this was my first trany problem, hell its my first problem with a PSD which is why I've stuck with them. Thanks for the advice, I'll consider the extra cooler and I've been thinking of changing the converter anyway since I've heard that it can improve shifting ect. so I think I'll do that and replace the seal at the same time.

[mschn99]

Originally Posted by firefighterbri

thank you. that makes perfect sense. I was alway under the impression that unless the transmission was shifing in and out of OD to just leave it in OD. If it was doing alot of shifting then lock it out, into tow mode so to speak. I have been towing like this for with my last three trucks for the last eight years and this was my first trany problem, hell its my first problem with a PSD which is why I've stuck with them. Thanks for the advice, I'll consider the extra cooler and I've been thinking of changing the converter anyway since I've heard that it can improve shifting ect. so I think I'll do that and replace the seal at the same time.

sounds like the perfect plan man .....change the fluid and filter while your there too if you dropp the trans out to do the converter.....that will do nothing but help. u might consider having a shift kit put in as well if your gonna have it out anyways, some swear by them, but you would need to talk to some of the guys who have installed them to get better opinions about those........Marc

[broncobuyer]

i had that problem with my 90 non turbo diesel, was towing a 7000 lbs load 80 down the highway and all of a sudden i couldnt see anything behind be but a lot of smoke so i pulled over and looked underneath and the underside of the truck was covered in trans fluid, the fluid hitting the exhaust was what was smoking. the trans puked all the fluid out the front seal. i let it sit for 2 hours to cool down and topped off the fluid and proceeded on my way. didnt have a problem with it after that but i didnt tow any loads with it anymore because i new the tranny was weak.