Trasmission leak at output/prop shaft

[77mercury77]

I just got my truck back from a rear main seal replacement and now i notice a trans leak at the output shaft seal.
I figure this one is easy, just disconnect at the u-joint, pull out and replace?
Are there any special tools, consumables, other things I should replace while i am in the process?
Also am i going to lose a lot of fluid or just need a top off?

 

[tom3]

You have it figured out about right. Not a lot of fluid back there normally. I always try to put the drive shaft back in just like it came out, mark it at the rear. I'm pretty ocd though.

 

[NickTransmissions]

I just got my truck back from a rear main seal replacement and now i notice a trans leak at the output shaft seal.
I figure this one is easy, just disconnect at the u-joint, pull out and replace?
Are there any special tools, consumables, other things I should replace while i am in the process?
Also am i going to lose a lot of fluid or just need a top off?

No special tools, just a 7/16” wrench or socket/extension for the driveshaft-to-pinion yoke bolts. Like Tom said, index the driveshaft with a paint pen or spray pain so it goes back on exactly how it came off (though you’ll know it right away if you put it on the “wrong way, lol”).

Use a big socket and hammer to install the new seal. Some folks will put a thin coat of rtv on the outer surface of the seal body. Coat the sealing surface with trans fluid or petroleum jelly before sliding the slip yoke back on.

 

[77mercury77]

Thank you, this is the info I needed. Any idea on torque values and use of loctite?

 

[NickTransmissions]

Thank you, this is the info I needed. Any idea on torque values and use of loctite?

You can use blue loctite if you want; factory service manual or haynes will have torque specs so double check but I believe those 4 7/16” bolts get somewhere between 26-40 ft lbs.

 

[mattbta]

Not sure if NNBS are the same as NBS but a shop installed a 4x4 output seal on my RWD after doing the rear main. They are two different parts. After convincing them it was the wrong seal and they put it in a lift and ran it to confirm the noise was in that area, got the proper seal on.

Watch your ears for the horrible noise that resulted:

 

[NickTransmissions]

Not sure if NNBS are the same as NBS but a shop installed a 4x4 output seal on my RWD after doing the rear main. They are two different parts. After convincing them it was the wrong seal and they put it in a lift and ran it to confirm the noise was in that area, got the proper seal on.

Watch your ears for the horrible noise that resulted:

Geez, sorry to hear that (figuratively and literally)! Glad it got fixed and hope no other damage of any kind was done.

Did they/you check the slip yoke for any grooves cut into it by the wrong seal being installed?

 

[mattbta]

Geez, sorry to hear that (figuratively and literally)! Glad it got fixed and hope no other damage of any kind was done.

Did they/you check the slip yoke for any grooves cut into it by the wrong seal being installed?

I should, forgot to inspect when I had it off to grease the splines. Would think it would have been obvious if so, but I don’t remember anything. Seems fine, so far.

 

[swathdiver]

I just got my truck back from a rear main seal replacement and now i notice a trans leak at the output shaft seal.
I figure this one is easy, just disconnect at the u-joint, pull out and replace?
Are there any special tools, consumables, other things I should replace while i am in the process?
Also am i going to lose a lot of fluid or just need a top off?

What year and is it RWD or 4WD?

 

[77mercury77]

Rwd