Transmission leak

[bmcgc]

The first couple months I owned my 99 Tj 4.0/AT, all was well. The last few months I have had a giant transmission leak. So big, that I have had to add fluid. We have only driven it a couple times since late April, so the leak has been on the back burner.

This weekend I am going to attempt to drop the skid plate for a look. If I get the plate off, I am going to hit it with degreaser and the pressure washer. Any guesses on the likely source of a large leak? From what I can see, it does not appear to be coming from the pan.

I've got a 65 Mustang, 67 Mustang, Class A motorhome, Jeep, 2 dogs, a lawn to mow and a wife. I can't keep up.

 

[JasterMereel42]

On my TJ, I've had 2 transmission leaks. The first was the output shaft seal of the transmission. There is a weep hole at the back of the transmission. If the fluid is coming from there, it is probably the output shaft seal. If you are going to replace that, also replace the input shaft seal of the transfer case since you'll have to take the TC off to get to the trans output shaft seal.

I've also had the shift shaft seal leak. I replaced it last November, and unfortunately, it is leaking again for me. You can diagnose that fairly easy by cleaning up the area by the shift shaft seal really well, wrapping a paper towel or blue shop towel around it, wait overnight, and check for red fluid on it the next day.

Also, this may sound dumb, but get some anti fungal powder spray to help diagnose the leaks. After you get everything cleaned up, let it dry, and then spray the white powder everywhere. The leaking red trans fluid will really show up then.

Have you taken off the skid plate before?

Also, if you are able to figure out where the leak is coming from, reply to me directly and I can give you some more advice.

 

[Cooper Smith]

The first couple months I owned my 99 Tj 4.0/AT, all was well. The last few months I have had a giant transmission leak. So big, that I have had to add fluid. We have only driven it a couple times since late April, so the leak has been on the back burner.

This weekend I am going to attempt to drop the skid plate for a look. If I get the plate off, I am going to hit it with degreaser and the pressure washer. Any guesses on the likely source of a large leak? From what I can see, it does not appear to be coming from the pan.

I've got a 65 Mustang, 67 Mustang, Class A motorhome, Jeep, 2 dogs, a lawn to mow and a wife. I can't keep up.

You didn't list kids, which would trump all of those in one. There's hope.

Are your vents plugged? If the PCV on the motor fails or vent on an axle/gearbox gets plugged, there's no way for built up pressure (from heat) to escape. This causes it to find the path of least resistance, which is usually not in our favor. This can be in the form of a pinion seal, trans input or output seal, diff cover seal, rear main seal, etc.

A trans pan is the easiest, and gives you an excuse to do a fluid change.

 

[bmcgc]

Finally crawling under the TJ to tackle this today.

I want to have the TC seals on hand if needed. I do not trust auto parts catalogs (long story). Can anyone provide the correct part numbers for the input and output shaft seals? 99 TJ, 32RH, bone stock.

 

[hear]

I don’t, I’ve only ever got the seal as part of the full rebuild kit.

 

[bmcgc]

I can't come up with the p/n's so I am not going to address the TC shaft seals unless I need too.

I spent the last 1/2 hour looking for the box with various sized PVC endcaps that I use to set seals. While looking for said box, I picked up and moved the box that says "oil seal seat kit" about four times.

I hope it is not going to be that kind of a day.

 

[JasterMereel42]

Finally crawling under the TJ to tackle this today.

I want to have the TC seals on hand if needed. I do not trust auto parts catalogs (long story). Can anyone provide the correct part numbers for the input and output shaft seals? 99 TJ, 32RH, bone stock.

I always go to Rock Auto and have had good luck with them.

 

[hear]

I can't come up with the p/n's so I am not going to address the TC shaft seals unless I need too.

If you don't have a drip at the bottom of the bellhousing, that seal is probably ok. It can be a bugger to get out sometimes. I've had to remove the pump from the case & then split the pump open to get that seal out before (it's way easier to drive that seal in that way!). But then other times I've been able to do it with the trans only pulled a few inches away from the block. ¯\_(ツ)_/¯

 

[bmcgc]

Skid plate came off ok. ATF everywhere. Pressue washed everything, tranny mount and front driveshaft new, Only about 1 qt came out of the transfer case. Taking a lunch break, then back on it.

 

[hear]

The shift selector shaft seal can leak an amazing amount without actually looking like it. Nobody ever thinks it’s the issue, but it’s probably the #1 cause of leaks.

 

[bmcgc]

The seals look great. Put a socket on the pan bolts and everyone of them is loose. Do I tighten to Spec or drp the pan and change the gasket?

 

[hear]

well that’s probably a problem. I think I would clean up the skid, torque the pan to spec, and see where that nets you. Torque spec is way lower than you’d think, like 20ish ft-lbs iirc.

Personally, I use the lube locker & pan with a drain plug to make trans maintenance much less painful.

 

[bmcgc]

Had to throw in the towel for today due to severe weather. We were working in the driveway. Everything is back together except refilling the transfer case and installing the skid plate.

Every one of the pan bolts was loose by 1.5+ turns. I torqued them to 150 in lbs and will see if I have any leaks. I suspect that I will. If I do, I will install the deep pan with a drain plug, two weeks from now. My SIL can help me every other weekend.

I know the transfer case takes 2 qts. Do I fill it until it weeps out of the top hole? When I drained it, I only got about a quart out of it, so it was low or there is still about a quart in it.

 

[hear]

Just fill it till it’s right up to the fill hole.

 

[bmcgc]

No fresh oil under the TJ this morning. Might have caught a break.

 

[hear]

No fresh oil under the TJ this morning. Might have caught a break.

Wouldn't that be a welcome change. Lots of leak sources end up running to the lip on the pan, so they look like they are pan/gasket leaks. 9 times out of 10 it's the NSS, cooler lines, or the selector shaft seal, since virtually nobody under-torques the pan bolts. You're probably the 5th dentist in the survey who doesn't prefer Crest toothpaste, too.

 

[JasterMereel42]

No fresh oil under the TJ this morning. Might have caught a break.

That's no fun. You needed to spend hundreds of dollars and several days in the garage fixing it.