About 6 months ago the front seal on my rear end was leaking diff fluid so I bought a new seal and put it on. After I had the whole thing back together and filled up with fluid I realized I forgot to put RTV on the splines of the yoke. Instead of doing it all over again I decided to just try it to see what would happen.

The last few weeks I've noticed the leak is back. Could this leak be caused by a lack of RTV on the splines of the yoke?

 

Sure, it's possible. Gen1 SBC harmonic balancers can leak engine oil the same way, and those only have 1 keyway. Thanks for the reminder because when I change to the solid pinion spacer instead of the crush sleeve in my 10 bolt rear, I will make sure to use some Maximum Gear Oil Resistant Permatex on those splines.

 

I would have thought oil leaking through the splines would originate from inside of the yoke where it connects to the driveshaft - not on the outside of the yoke where the seal is.

 

Oil will leak through the splines, which is why GM sealed them with thread sealer. Your leak however is not from the splines. It's either leaking around the yoke or around the outside of the seal where it goes into the housing.

 

It should really go without saying, but a quality name brand seal is often a much higher quality part then the local parts store's house brand. It might sound odd, but one seal can seal better than another. A pinion seal is hard enough to get at, I wouldn't try to save a few bucks there. Not saying that's the problem, but it's something to think about.

I'm not sure I'd worry too much about that leak. Every 10-bolt I've ever seen had a 1/4" thick coating of grease around the center section. I've seen plenty of pinion leaks that were bad enough there was a band of grease on the exhaust and floor, etc around the yolk. That doesnt look that bad.

 

I only use the pinion seal that I get from the dealership. Not even going to mess around with the cheap National brand you find at the auto part stores. If not for the Delco seal, then Timken is an option also.

 

I had a groove worn in my yoke even a quality seal was leaking a little. I ended up using a speedi sleeve and problem fixed

 

The only reason I care to fix it is because it leaves a small puddle of gear oil on the floor after every drive and I'm tired of having to wipe it up after I back out the car so my dog doesn't get at it.

I did get this seal from Advanced Auto so the quality could be bad. Is the dealer the only place to go for a quality seal?

 

I used an autozone one, made in chine leaked at the worn groove. Bought this one from yukon made in America also leaked at the same place. Fixed the groove problem gone.

https://www.yukongear.com/productdet...px?ProdID=8738

 

You definitely have to insure the pinion flange has a good seal surface on it. Get a new one or install a seal sleeve. You would be surprised how often this is overlooked. People assume the seal is bad.... it usually is but the question is then why? The differential doesn't typically see high enough temps to cause the seal to turn hard and crack. Usually it's because of contamination - dirt gets into the seal, embeds itself in the rubber, and acts like a cutting tool on the pinion flange - leaving a groove where the seal rides and not allowing it seal effectively.

GD

 

I smear a thin film of RTV sealer around the seal before driving it in. This will help seal up scratches in the housing from prying the old seal out. You can also use thread sealer.

 

Way cheaper at RockAuto. $10.20
http://www.rockauto.com/en/catalog/p...r+sleeve,13976