Leaking Pinion Seal

[1972GMCsierra4x4]

Recently I replaced the gearset, pinion bearings and pinion seal on my 72 K-2500 w/ the DANA 60. This morning on my way to class I started smelling hot oil. I live real close to school and I whipped into the parking lot and my brand new pinion seal was leaking. Oil was leaking out from behind the flange and had been flung everwhere. Any idea what caused this? Bad seal or what?

[68gmsee]

Seal would be my first suspect. I've replaced seals on transmission output, timing chain cover, a rear seal on my Massey and even on my post hole digger that leaked shortly after installing them. For some reason they're not making them like they used to.

If you determine a defective seal and, if possible, find out the manufacturer of the seal and don't buy the same brand again.

[1972GMCsierra4x4]

The seal is literally brand new, it has MAYBE 45 miles on it. I don't see how it could fail, but you never know

[Wrenchbender Ret]

I had my 56 1/2 ton do that. I pulled the seal out & the spring in back of the lip had fallen out. I put in a new seal carefully & it is fine now.

[RIDE-RED 350r]

I would speculate that improper installation is likely the cause of quite a few new seal failures. Not saying it's your fault, but in some cases it can be very easy to roll the lip of the seal during installation.

The other thing is the wear on the surface of the spinning component that mates with the seal lip. Being that you have a new gearset, this is not likely to be the case. Just check the sealing surface of your pinion shaft when you pull the old seal and make sure it doesn't have any burrs or any other little defects that could cause the seal to leak prematurely.

Always lubricate the seal lip and the part the lip will ride on with the lube it will be working with before installation.

Also if possible, it helps to slowly rotate the seal itself (if possible) or the part that will mate with the seal lip as you slide it into it's seated position.

This might be a little more tricky for you since you won't be lulling the pinion just to replace your leaking seal.

If you replace the seal taking extra precautions being 100% certain it is installed proper and it leaks again, I would be suspect of something defective with your pinion.

[Stepside Jim]

Just a thought... I also battled a leaky seal, or so I thought.

Mine was the gear oil was able to work it's way down the splines of the yoke, then came out around the large retaining washer.

Simple cure, put some sealer inside the splines of the yoke before installing the yoke.

If this is your problem, do not put the sealer on the pinion splines, you will push the excess sealer into the housing.

Good luck either way, Jim

[1972GMCsierra4x4]

Thanks for the advice guys, but as it turns out, the seal failed because I screwed up. I put too much preload on my opinion and my rear bearing failed. I guess trying to save a few bucks ended up biting me in the butt big time. At least I caught it before my new gears got ruined

[RIDE-RED 350r]

Awe man that sucks!! Rear end setup all over again.

[MikeB]

Originally Posted by 1972GMCsierra4x4

I put too much preload on my opinion and my rear bearing failed. I guess trying to save a few bucks ended up biting me in the butt big time. At least I caught it before my new gears got ruined

Here's what I use for pre-load. Found it for around $30 several years ago.

http://www.thetoolwarehouse.net/gear...z5vBoC817w_wcB

[RIDE-RED 350r]

Bearing preload is very important and not something you can usually get away with "close enough" for from what I have learned.

An inch-pound torque wrench like Mike B posted is what you need.