Tranny Leak?

I hate to start a new thread but after my searches I didn't come up with an answer.

I HAD a descent drip of tranny fluid after I drove up a steep grade for a while (I-15 Cajon Pass). It actually left a good puddle on the ground. I looked and couldn't figure where it was coming from. When it was cool I tried to wipe the area down to establish the leak and had no success. I noticed that it is recently oily above the tranny where some of the wiring harnesses go back but I could not determine that it was tranny fluid. There was a hose that seemed to start at about 8" blow the tranny dip-stick and went back to either the back of the tranny or the top of my 231 TC. I could not figure out what it is with my Haynes Repair Manual. Any suggestions as to what I should check or what that hose might be? Vacuum hose?

BTW I have yet to notice a drip since. I have been watching the fluid level and for drips like a hawk. I read (in the Haynes Repair Manual) that too much tranny fluid would cause a leak but no one has added any in a while and the fluid level has been good.

There aren't any vacuum hoses for the AW4, and the only transfer case hoses are with the NP231 used for engaging the front axle and for triggering the switches.

The transfer case and transmission both have vent lines, however, and overheating or overfilling can cause the vent lines to "burp" fluid.

The places where an AW4 can leak are...

Vent tube
Dipstick tube (at the pan grommet, and a few inches up where the two parts of the dipstick tube are joined and sealed by an oring and a light press fit
Shift shaft seals (both sides.)
Transmission Pan gasket
Front Pump seal (where it seals to the housing - it's a BIG oring!)
Input shaft seal (behind torque converter)

Any or all of these can present anywhere along the length of the transmission pan.

Output Shaft Seal (either on 2WD driveshaft or between the transmission or transfer case on 4WD)
Transfer Case Adapter/extension housing seal (same seal - it's a few inches forward of the transfer case or a distinct parting line a few inches in front of the driveshaft on 2WD.)

Both of these can present as an output shaft seal leak - so they'll want to be checked.

This is a case where you probably want to put your XJ up on four stands, clean the underbody around the transmission thoroughly, and let it dry. When it's dry, have a helper THAT YOU TRUST start the engine and run through the gear ranges - while you watch for leaks underneath. Take a bright flashlight with you - even if it's noon (it comes in handy...)

Of course, this is only if the leak is red. Note that engine oil can leak from a couple places that will present like a transmission leak. If the leak is black, clean and check the right side of the valve cover, the base of the distributor (it drives the oil pump,) and the oil filter right-angle adapter housing.

5-90

Thank you for the advise. I have NOT had it leak since. It was about 90+ degrees out, I was going up a steep grade @ 60-65, my engine was running a tad warmer than it normally does, and I have 35s w/4.88 gears. I think it sounds as if I 'burped' fluid. I have fluid all over my undercarriage and on the rear tailgate. The fluid was a tad low but otherwise fine.

Does these factors warrant a 'burp'? Does the fluid 'burp' out of the vent and where exactly is the vent?

And last, does it sound as if I need a bigger tranny cooler?

BTW I have the tranny cooler that runs in front of the radiator.

"Burping" can happen for a number of reasons - the three most common being overfilling, excess heat, or an obstruction somewhere hindering return flow (more or less in that order.)

A burp can be a one-time shot, with no repeat, and it may have been caused by a momentary overheat or a brief obstruction in return flow.

The vents are usually at or near the top of the case, and I believe that both the transmission and transfer case have vent hoses that go to little poppet-valve assembles, and the hoses are usually clamped up near the rear of the engine - on the firewall or on the engine. If you take a moment to follow them, they're not that hard to find - just getting at them is a pain.

Check and make sure the valves haven't got restricted - they should just pull right out of the rubber hose, and blow thru them. You should be able to blow air OUT - the valve is supposed to keep things from getting IN (apart from air when everything cools down.)

You can also blow through the hoses to make sure they aren't restricted, and make sure (visually) they haven't gotten kinked, blown out, or squished between something.

That's all I can think of for the moment!

5-90

My 96 started burping fluid this summer. You had to drive it 20 miles or more and get it hot to do it . I added an aftermarket cooler and seems to fixes the problem.

Thanks for posting this problem. I have a similar setup and just had this happen for the first time. I could not find any defects in the pan, gasket, or cooling lines. I had the same thing happen on Sunday coming home from a wheel'n trip on the Rubicon Trail. 90+ degree day after coming through the canyon on HWY49 turned East on 80 and a friend following behind me pulled up to let me know I was blowing smoke. I had noticed the engine temp earlier was just past 210 so I turned off the AC. I have a large trans-cooler in front of the radiator and use the radiator cooler also. I run 5.13 and 35's 242 T-case. ATF all over the bottom of the Jeep. I used the pressure washer to clean area. After it dried I parked in garage no drip since. I plan to drive it tonight and see if it will happen again. I am happy with the burp theory. Any place to put a temp gauge sender on it?

Thanks,
Sean

I just spoke to an associate of mine who was a Chrysler Dealer Service Writer. He said the fluid gets so hot that it can seperate, producing an acid that when new fluid is added it can cause the clutches to sieze. He recommended a 'Powerflush' and adding two bottles of Lube Guard along with a TruCool tranny cooler.

Does this make sense?

Clear as mud to me. I inspected and drove mine last night not a hint of a leak anywhere. In your picture you asked what that hose is. On mine that is the vent hose from the T-case. At this point I'm gonna change the fluid and call it good.

Sean

Overheating caused by a larger than normal load, a hot day, coupled with either too high or too low a fluid level, leads to foaming. The fluid actually gets air whipped into it and it expands. This is made worse if water has gotten into the tranny via condensation. The water boils, starting the whole thing off, until it comes out the overflow/vent. This is very common. Just make sure you have the correct fluid level. A trans cooler helps. If the tranny has gotten hot enough to do this, it wouldn't hurt to drop the pan, replace the filter and replace the fluid.

5-90 said:

The places where an AW4 can leak are...

Output Shaft Seal (either on 2WD driveshaft or between the transmission or transfer case on 4WD)
Transfer Case Adapter/extension housing seal (same seal - it's a few inches forward of the transfer case or a distinct parting line a few inches in front of the driveshaft on 2WD.)

Click to expand...

I pulled my NP231 to install a TeraLow. When the transfercase seperated from the Transfer Case Adapter/extension housing, a bunch of ATF gushed out. Should that be a dry bay? The tcase had plenty of fluid in it. I'm suspecting a bad AW4 output shaft seal.

Blazair said:

I pulled my NP231 to install a TeraLow. When the transfercase seperated from the Transfer Case Adapter/extension housing, a bunch of ATF gushed out. Should that be a dry bay? The tcase had plenty of fluid in it. I'm suspecting a bad AW4 output shaft seal.

Click to expand...

Nope. The output shaft seal on the 4WD AW4 actually seals on the input shaft for the transfer case. If you'd looked, you'd have seen a good amount of air between the sealing lip and the output shaft, and the splines of the output shaft would have been right under the sealing lip anyhow (can you say "Won't seal worth a damn?" I knew you could...)

So, what happened for you is perfectly normal. Reassemble, top off, and call it good. The BA-10 and AX-15 are the same way - sealing on the transfer case input seal allows the entire assembly to be a couple inches shorter.