differential leacking - adding sealant to oil?

[Oliver S.]

My '65 Corvette differentail leaks - over the last 5 years increasingly. Initially I planned to have the oil seal replaced - a laborous work. Now I've heard about the possibility of adding a sealant fluid to the differential oil.
I'd like to know if this is a durabale and accepted fix or not? If so what product do you recommend?

Regards
Oliver

[Tom H.]

Re: differential leacking - adding sealant to oil?

I don't have any experience with the stuff. Have you determined the exact cause or place where the leak is happening ?
A correct fix is the only sure bet. JMO.

[Joe L.]

Re: differential leacking - adding sealant to oil?

My '65 Corvette differentail leaks - over the last 5 years increasingly. Initially I planned to have the oil seal replaced - a laborous work. Now I've heard about the possibility of adding a sealant fluid to the differential oil.
I'd like to know if this is a durabale and accepted fix or not? If so what product do you recommend?

Regards
Oliver

Oliver-----


I don't think you'll find that any sealant added to the oil will significantly reduce the leak. You could try it as it's pretty simple to add it and I don't think it will do any harm. However, if it doesn't solve your problem as I expect will be the case, I'd do a proper repair and change the differential lube at the same time.

It is possible to replace the pinion seal with the unit in the car. However, if the differential has never been rebuilt, now might be the time to remove it from the car and have it professionally rebuilt.

[Michael F.]

Re: differential leacking - adding sealant to oil?

Oliver-----


I don't think you'll find that any sealant added to the oil will significantly reduce the leak. You could try it as it's pretty simple to add it and I don't think it will do any harm. However, if it doesn't solve your problem as I expect will be the case, I'd do a proper repair and change the differential lube at the same time.

It is possible to replace the pinion seal with the unit in the car. However, if the differential has never been rebuilt, now might be the time to remove it from the car and have it professionally rebuilt.

Well said, a leak means a worn seal. A worn seal could indicate other problems. Time to fix whats worn or broke.

I stay away from 99% of the miracle oils and sealers.

[Domenic T.]

Re: differential leacking - adding sealant to oil?

Oliver,
on the other side of the coin, if you don't have a lot of miles on the diff then the sealscan get old.
At the very least I would look at the lube and see if it has a tint of metalic particals in it. If not and your rear end doesn't make noise when you drive, then I would change all the seals and the back plate gasket after you inspect it for wear.
The rubberin the seals gets hard as the years go by and the seals are not soft enough to seal.
I took my 57 chevy rear end out and inspected it for signs of wear and changed the hard pinion seal and paper gasket, it's just fine now.
Depending on conditions, the rubber seals usually only live about 20 years and if there is a good lube in the rear end to protect the bearings from rust, you can get lucky.
Years ago my 67 coupe pinion seal went bad after the car sat for years.
I noticed the leak and decided to do it when I did the frame off. I drove it that way untill I did the restoration. When I took it out and put it on the bench I found the pinion bearing loose and the oil full of metalic.
The seal was so bad that it let moisture in and rusted the bearing. That with the driving I did before I found the problem ruined the pinion bearing.
DOM

[Tony S.]

Re: differential leacking - adding sealant to oil?

Have you looked under your car to see specifically where the leak is coming from? Sounds like a vague question, but I had a C2 that had a cross threaded plug. The fluid kept leaking out of the area where the plug didn't quite seal. I put some tape dope on the male threads of the plug and fixed good as new.

[Gary R.]

Re: differential leacking - adding sealant to oil?

Those sealants are not going to work, try if you like but I doubt it.

Differential leaks can be from the pinion seal or yoke( most common), side yoke seals, rear cover, over filling it, installing the wrong size bolts for the spring and breaking the cast iron, or just plain poor installation of any of the above.

Replacing the pinion on the car is doable but best done on a lift.
Here is a link to a thread I wrote a few years ago on doing the job. As others said, if it hasn't touched in a long time you may want to check it closer. Going to the link source will also pull up the other diff threads I wrote covering simple rebuilds to custom diff's good to 1000hp.
Good luck.

[Richard G.]

Re: differential leacking - adding sealant to oil?

The seal was so bad that it let moisture in and rusted the bearing. That with the driving I did before I found the problem ruined the pinion bearing.
DOM

Or possibly the bearing fit failed and allowed the sealing area of the yolk to run out and then the seal failed. I do a lot of Root Cause Analysis and it often ends at "The chicken or the egg"!

Best of luck on finding and fixing the leak. I'm betting the pinion seal is gone and will require replacement. Watch for grooving in the yolk where the seal rides.
Rick

[Mike E.]

Re: differential leacking - adding sealant to oil?

Interesting; "yolk" and "chicken and egg" in the same paragraph!

The seal was so bad that it let moisture in and rusted the bearing. That with the driving I did before I found the problem ruined the pinion bearing.
DOM

Or possibly the bearing fit failed and allowed the sealing area of the yolk to run out and then the seal failed. I do a lot of Root Cause Analysis and it often ends at "The chicken or the egg"!

Best of luck on finding and fixing the leak. I'm betting the pinion seal is gone and will require replacement. Watch for grooving in the yolk where the seal rides.
Rick