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Jeep 231 Transfercase and SYE leak fix

On my last trip down to Tillamook state forest in Oregon, climbing up a rocky, muddy hill I was bouncing around pretty good and wacked my rear diff a few times. I got out and noticed what appeared to be some red fluid. I shrugged my shoulders and figured it was either the guy in front of me or I must have a small leak. Needless to say after getting out of what I was in and parked at the top of the trail I smelt burning Transfercase fluid. Looked under my Jeep and sure enough I was leaking. I feared the worst. Oh, NO we are going to loose the Transfercase on the trail. I was really worried since its never leaked before so of course I was a bit excited.

One of the guys with me erslll suggested that possibly my vent was clogged and blew free or I was leaking out from the rubber washer behind the yoke. At first I thought he was totally nuts and wouldn't accept that answer. Reached the top of the trail head and after a while we ended up at the staging area. I barrowed some Transfercase fluid and make sure it was topped off. Drove my Jeep over to a friends house for the evening before returning home the next day. I was to address my leak as soon as I got home.

Needless to say there wasn't a leak anymore and hey it must of been a fluke? WRONG, a month later I was doing some playing at work and climbing a hill or two and when I got back home there was a puddle of what looked like Transfercase fluid under my Jeep. Ive determined in my mind it must be when the Jeep is climbing, which puts pressure on the rubber star washer allowing the leak. Ok, this is it, Im mad. Im going to figure this out yet. I did some looking at below is what I found out. Needless to say. I was wrong and the little rubber star washer was the bad person.

Tools: Time:

1 1/8-inch socket
Couple of rags
Brake Cleaner

Aprox. 20 minutes

This fix isn't to hard and Ive yet to see it documented anywhere. A member on the forum suggested it to me and as far as I can tell it hasn't leaked in the last two days even after climbing a hill or two. Written by kizer, if you have any questions or comments about this install visit


Under my Jeep I noticed a few drops of fluid.

Good inidcator that Im leaking. Transfercase fluid all over underneth my TJ.

Sprayed all over the floor of my TJ and some on the muffler. Does it stink when it gets hot? Well enough to notice and wonder what the heck is that smell?

After removing the driveshaft it was time to figure out if it was the yoke that was leaking or the seal around the yoke.

Looking inside the yoke around the nut there is a little bit of fluid. I did not find any fluid around the yoke or on the Transfercase. It was a pretty safe guess that its leaking out of the yoke from behind the nut holding the yoke on.

I used an air driven impact gun and a 1 1/8 inch socket to remove the nut. Becareful if your using air. You do not want to remove the nut and have it spin wildly on the shaft. Unless of course you have a spare nut.

After the nut was removed I noticed even more fluid sitting behind the nut, around the shaft and the rubber star washer looked soaked.

Gently rock an pull on the yoke to remove it. It will feel really snug.

After the yoke was removed I noticed there was a fair amount of transfercase fluid not only behind the rubber star washer, but as well on the front of the washer.

Inside the yoke on the bottom I noticed what looked like a piece of grease. I removed the grease and guess what? It was a thin slide of the black rubber star washer that appeared to be sliced off when I removed the yoke. I wonder if it was loose before or just after I pulled the yoke? Either way we are leaking.

Here is a side profile of what the rubber washer looks like in line with your splines off your output shaft.

Take a clean rag and spray it with some brake cleaner. We want the surfaces as clean as possible so the RTV can stick to it.

Slowly work your way around the out put shaft and clean all of the remaining Transfercase fluid off the shaft. Pay special attention to getting into the groves of the shaft. You are only concerned with the end of the shaft and about an inch back.

Clean the inside of the yoke as well as well as you can. Remove any pieces of the rubber star washer if there is any. Also making sure to clean the groves in the yoke.

Prior to placing RTV allow the brake cleaner used to dry, which shouldn't take more than a minute or two since it evaporates rather quickly.

I placed a very thin bead of RTV as close as I could to the smooth inner setction of the shaft that the star washer held onto.

After later consideration it dawned on me. I still haven't taken any new photos, but instead of placing RTV on the splines place them inside the yoke. The reason is you do not want to push RTV back into your Transfercase, which applying on the splines might. Placing the RTV inside the yoke will cause the RTV to want to stay near the nut.

Read prior step

KEEP in mind you DO NOT want a lot of RTV on the shaft. You DO NOT want RTV to get pushed into the Transfercase because the splines do not have much clearence and clogging up your oil pump can be a very bad idea.

Reinstall your yoke and torque down the nut with some lock tight to 150flbs. Reinstall your drive line and your all done.

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