HELP! Rear trans seal still weeping after replacement

2003 Tundra
4.7L
2WD
187,000 miles

About a year ago I had my mechanic replace a weeping seal that goes between the drive shaft and the transmission. I bought the seal from Toyota. It is not aftermarket.

Since he had to drop the drive shaft to replace the seal, I had the driveshaft rebuilt and balanced while it was off the truck.

Things were fine for about 9 months but now it's weeping again. Can anyone give me a heads up as to why? Anyone know the proper procedure for fixing this? I'm assuming if I replace it again with another Toyota factory seal, it's just going to leak again.

I've been using the same mechanic for 5 years because he's skilled and honest...so I'm reasonably assuming it's nothing he's done incorrectly.

Any help would be appreciated.

 

If he's honest, he'll do it again till he gets it right.

 

I had the same issue on my 06 4.7. I replaced it will a oem gasket and still had the exact same seepage as original.

 

I vaguely remember reading a forum post (maybe this forum or another one) about continued weeping even after the seal is replaced...although I can't seem to find the original post.

The weep is very slow...so I could just keep an eye on the fluid level and call it good...but I'd rather fix it if possible.

 

The yoke on the end of the driveshaft might be damaged. Seals can cut a grove into the sealing surface so the new seal will not seal. I would replace the driveshaft end/or inspect it carefully. Sometimes just seating the seal at a different depth so it rides in a different area will stop the leak.

 

Have mechanic check extension housing bushing.

 

Loctite 5172 used on the od of the new seal should take care of that. Those seals come with a dry sealant on the od but tend to leak anyway.

 

Replace the seal and put silicone gasket maker designed for oil on it. I had that same problem. I had a friend do it for me because I was injured at the time and did not use sealant. I had to replace it

 

I’ll confirm that I’ve also read the continued problem even after new seal install.

 

I despise seals. I think they are magic. I have no idea what makes one work and one leak, and I've replaced dozens of them. Sometimes they last forever, sometimes I'm doing them again a week later and that time they last forever....or not. Hate those suckers.