Hi all!

Two weeks ago I bought a 93 GMC Jimmy with 158,000 miles on it. I got it for $1000 because the injectors were leaking. The past couple weeks I've been fixing it up as a daily driver and have done quite a bit of work on it. I replaced the injector assembly and feed lines, replaced the horn fuse, replaced the blower motor relay, replaced one of the rear glass lifters, replaced several bulbs, changed cap/rotor/wire/plugs, changed fuel/oil/air filters, changed oil, ran Seafoam through the intake, cleaned the EGR and PCV valves, fixed a sagging headlight bracket and swapped in a better stereo from my wrecked 94 Jimmy.

All of that work has been very positive. I'm having one other major issue. Last week I drove the Jimmy about ten miles round-trip to pick up my daughter from a school dance. On the way home I noticed white smoke coming from underneath the front of it. When I got it home I checked around and found what looked like bad transmission fluid all over the underside of the truck. I left it over night and cleaned it all off in the morning. I ran it again on a short trip and didn't have the problem again.

A couple days later I made a longer trip and had the smoking problem again. I got it home and the underside was coated with fluid. Sensing a transmission problem, I got some Seafoam Trans Tune and added a half pint and drove it around for the day. When I got home I dropped the pan somewhat, drained out a few quarts of fluid and put a quart of Lucas transmission fluid conditioner in along with enough fresh fluid to bring it back up to proper operating level. I took it out for some test driving and the transmission shifted fine and seemed to be driving OK.

Today when I got on the freeway it started puking fluid again, creating a big white cloud of smoke. I let it cool down and washed the excess fluid off the underside and drove home. The fluid is still somewhat burned. I was hoping that the Lucas would extend the transmission life for at least a couple months and end the fluid puking long enough for me to drive it until I can get a strong rebuilt transmission. That's not an option until at least September when my wife starts working (she just finished graduate school). What can I do in the meantime to get more serviceable life out of this tranny? I've read varying opinions on here; some say to get a flush & filter change, some say to do nothing. Should I just prepare a suitable eulogy for this 4L60E?

 

Where is the fluid coming out of? Could it be just a blown line?

 

It's definitely coming from the vent tube on the top of the transmission. I checked all the other possible places it could be coming from. The tranny cooler lines are all in good shape and show no signs of leaking.

I was going to take the Jimmy over the mountains this weekend but I've decided to leave it home and drive my trusty 92 S-10. That truck is my go-to ride.

 

Sounds like the Transfer Case input shaft seal is bad, transmission is forcing fluid in the transfer case and its puking out the vent, you will be able to tell if its overfull, the fluid only needs to be up to the plug. Remove the fill plug on the transfer case and see if its overfull, if it is you will need to remove the transfer case and replace the input shaft seal

 

I just got back from my trip to Yakima. I'll check the fluid level on the transfer case and get back to you. Thanks for the information!

 

that happened on my 96 and it ended up being the rear seal on the tranny. what it was doing was blowing the fluid right out the vent on the transfer case like Nvidia78 said.

 

My thoughts.
No rear seal on a 4x4 tranny, the t-case has an input seal and if that leaks the t-case will fill with tranny fluid and then the fluid has two places to go, into your vacuum system or out the rear output seal.

If the rear seal (2 wdr tranny or T-Case) is leaking you will see fluid slung in a circular pattern on the bottom of the truck, and the fluid will fan out from there to the whole underside of the truck, the smoke is actually blue and its coming from fluid contact with your exhaust pipe.

Now if this fluid is really coming out of the tranny vent tube, which is located ont eh top of the tranny next to the bellhousing, then its overheating. That leads me to believe you have a plugged tranny cooler or your pump isnt working. Both can be tested with the tranny in the truck, by a shop. There is a test port on the drivers side above the shift linkage.

 

Hey gang!

I finally had a chance to check out the Jimmy this evening. For some reason my wife insisted I replace the brakes on her Pontiac before I did anything more on my project. You married guys understand.

I pulled the fill plug on the transfer case and about a cup of fluid came out. It looked like a mixture of transmission fluid and gear oil. It smelled exactly like what was coming out from underneath the truck. I think it's safe to say that for some reason the transmission fluid is mixing with the gear oil.

So what should I do now? The fluid is spraying out somewhere near the front of the transmission. It has coated the back of the engine oil pan and everything back to the transfer case. The fluid gets on the exhaust crossover pipe under the front of the transmission pan and that's where it starts smoking.

I'm going up to Canada next week so I won't likely be doing any more work on the Jimmy for a couple weeks. That will give me time to figure out what to do next. What would you do?

 

Sounds like you have a combination of problems. A leaking front seal on the transmission and a leaking front seal on the transfer case. Have you verified that the transmission fluid is coming from the front of the transmission where the torque converter hub engages the front pump?

 

A cup of ATF isnt a lot, especially if your front tires are on ramps or jack stands.

GM t-cases are filled with automatic tranny fluid (ATF), unless its an all wheel drive unit, and then it has a limited slip addative. No gear oil in our t-cases.

Your positive your leak is tranny fluid and not motor oil. As in motor oil leaking out the intake manifold gasket at the back of the engine, which means it leaks down the back of the engine and onto the cross over pipe.

If it is tranny fluid leaking onto the cross over pipe, it could be coming from the tranny vent tube, which is located on top of the tranny behind hte bell housing, it too will leak onto the cross over pipe. If your overflow tube is leaking, you either have too much fluid, or your tranny is overheating for some reason, like a plugged auxilary cooler, or pinched/plugged cooler line.

IF this is leaking engine oil or tranny fluid from insdie the bellhousing, pull hte cover and look inside. If you have either oil leaking in there is will be slung in a circular pattern.

Post up what you find. There are some tricks to fix each leak.