I've still got a problem with a transmission leak from between the splines and the yoke of the output shaft. I have checked all my manuals for a remedy. I can't find a reference to this problem. It only leaks when it has been parked overbite and doesn't leak when I am driving it. I think it has to be fluid draining back into the trans from either the cooler or the converter. If it was the converter then I would think that it would hesitate when I put it in gear as it pumps fluid to fill the converter. That seems to be the indication that jeep does when the converter drains back. Mine has no hesitation. Is there a check valve that would prevent fluid from draining back from the coolers? Looking at the way the transmission is sealed, it appears that fluid should never get to a level where it could leak past the splines. Has anyone ever had this problem?

 

What transmission is that? A518?

 

It's a 727 3 speed. Thanks

 

Yes, I had the same problem on my 89 donor engine and trans. Someone had replaced the rear seal at one time and didn't get the yoke back on tight enough. Mine leaked like crazy. Dodge dealer was the only place I could find the seal also(about ten bucks).

 

Thanks Peyton. The first time it leaked was after I retired and I didn't use the truck for several days. I walked out one morning to find a puddle of fluid and thought "rear seal". I pulled it apart and saw what looked like fluid coming from the splines. I figured as long as I was there I would pop the seal and replace it. I went to Advance and bought a seal, came back and removed the seal only to find that I had the wrong one. Took a week to get the right seal. I applied some heavy grease to the splines on assembly which may have helped temporarily. I don't really know because there is no problem when the truck is driven daily. I know that the nut is torqued correctly but the problem I see is that the yoke slides over the splines and the nut torques against a raised area on the shaft (not against the yoke it's self). That leaves the yoke free to move in and out slightly as it would on any other transmission (the 727s that have a yoke with a solid end). I am sure that there is wear on the shaft and yoke after 180,000 miles but I can't see how a new one could stop fluid from passing by without some form of seal. Thats the reason I was thinking that the fluid should never reach that level in order to seep past. Please keep the ideas coming and thanks.

 

I had to really crank on mine with a 3/4 drive ratchet to get mine tight. I put a little never-seize(sp) on the threads to relieve some friction as it is a locking type nut. Before I had mine off you could wiggle mine too, hence the fluid all over the place. There is a large ball bearing in the rear of the trans, when you remove the yoke it can be seen easily so there is going to be fluid there just looking for a place to come out. Maybe a new seal(if you're going to be in there anyway), a little sealant on the splines, and maybe a hardened washer under your nut(to take up the slack) will work. If it wiggles it's going to leak/ wear out your seal prematurely.