pinion seal leaking. Is it the oil??

[Posm]

I changed to sythetic 75/90 rear lube 15 K ago and now I see leakage at the rear pion seal. Should I change to a heavier oil before I start looking for other causes. Any input would be helpfull.

 

[Whitmore]

IMHO

It aint the oil its the seal, true the syn oil will flow easier and find a bad seal but you need to change out the seal... ... ... ... ..... Kevin

 

[LSMITH]

I agree with Whitmore, it was going to leak no matter what, just the slick synthetic found the bad seal quicker and will come out in a higher quantity. Pinion seals leaking are pretty common on our trucks.

 

[Posm]

Whats involved in a change? Any special tools or procudures to put a new seal in? Would you go to the 85-140 lube for summer?

 

[Okie-Go]

That is the only time I had to put truck in the shop. I had the factory fluid. As I was told the tech said he did not have to put all new fluid in. He just topped it off.

 

[Whitmore]

Posm, its not bad, you block your wheels and than pull the driveline and the yoke too , the seal is than easy to pop out with a seal puller or a screw driver, clean the area up and put in the new seal, prolly the hardest part is getting the new seal started evenly, some arent bad and others can be a bugger, top off the oil , re-installe the driveline and get it on ... ... ... ... ..... Kevin

 

[Don M]

Posm,



Many brands of synthetics are based on PAO, (polyalphaolefin's).



PAO's do not work as well with many seal materials used in our trucks. So manufacturers add in esters to help with the seal compatibility and help with leaks. The esters work much like the dino oil base stocks do to help swell the seals slightly and keep them pliable. The drawbavk to too much ester is the lubricity of the oil is lowered and the manufacturers dont like to add too much to keep wear numbers down. Depending on how much ester was added to the batch is oftentimes the reasons the seals will begin to leak. The arguement has gone back and forth on how synthetics do or do not cause leaks. I have heard everything from "the oil is slicker" to "the slicker oil will find its way to the existing cracks or marginal seals"

IMO, that is hogwash and tribologist and oil chemist will tell you it aint so.



Many of the top quality synthetics address the seal compatibility issues better than others do.



Don~

 

[Posm]

Well, I'll have to say I don't like what anybody here is saying. I was hoping to find some kind of special spray, preferably in an aerosol to fix the problem. short of some kind of quick fix, I guess I will go get a seal.



Don

I was not so much blaming the synthetic as I thought the lower end 75 weight might be more apt to leak than some thing with a 85 or 90 lower end. Would you recomend 85-140 for summer use?

 

[RKelly]

POSM:

I see in your post that you have a limited slip rear. I remember reading, somewhere on this site, that the friction modifier that is added to the normal gear oil can be rough on seals (my seal went at about 20k miles).

Just food for thought.

Ray

 

[Extreme1]

A couple more things on the seal swap...

The nut torque on the Dana 80 (which is what you have) is 450 ft-lbs. The easy way to be sure to get it back to spec with out a King Kong torque wrench is to mark the nut and the shaft with a scribe. When you reassemble, turn the nut to line up with the mark on the shaft (or a tiny amount more) using a large air impact wrench.



The yoke is on tight. I had to use a puller to remove it and drive it back on when done. The seal was the easy part on mine.

 

[Texas Diesel]

Re: A couple more things on the seal swap...

Originally posted by Extreme1

mark the nut and the shaft with a scribe. When you reassemble, turn the nut to line up with the mark on the shaft

Excellent idea!!

 

[Southbound]

4TH SEAL

Sorry to hear of the bad-luck on your seal. I have had a lot of troubles with mine. I think part of the troubles is I that I had to replace my axle due to a wreck but any way the dealer has had a time with the front seal. I was able to put 20k on this last seal before leaking. I am wondering if perhaps my breather line might be restricted which could cause some pressure maybe causing the leak???... who knows. I have had a well known axle shop in Dallas tell me that these seals are 50/50 on holding up. Keep us posted on your findings and good luck!



Southbound

 

[Extreme1]

One more thing...

Coat the outside edge of the new seal with a thin coat of silicone RTV sealer.

 

[Joseph Donnelly]

Coat the sealing lip of the seal and the companion flange wear surface with moly lube, like camshaft lube or moly wheel bearing grease.