Rear Axel Question

[LanceLyon]

I have an oil leak on the rear axel that puzzles me a little. It's at the center of the differential, and I assumed it would be at the gasket between the axel housing and the driveshaft connection.

After cleaning up the area a little, it appears that the leak is coming from the area where a bracket is attached to the housing at the center of what would be the rear cover on most differentials. The bracket surrounds the solid shaft that actuates the hand-brake on the left-rear wheel.

Is this bracket that I am talking about attached to the axel housing by screws or otherwise? Any ideas of how to seal the leak, short of removing the axel housing?

 

[Dave Russell]

LL,

As far as I know, the bracket is just welded to the axle housing. Very unusual for it to leak, but I guess it's possible.
D

 

[Brian N.]

Hmmmm. Let me think on this a bit.

Possibly the bracket weld got wrenched and has pulled the case and cracked it. I have seen this happen elsewhere with welded brackets. That little bracket is not carrying a very big load at all, so maybe it go banged when the axel was out for some reason. Or someone was jacking the car by the differential and the jack slid back off.

Anyway, here's a possible solution.


Use some paint thinner to thoroughly clean the area. Use a good light and possibly a magnifying glass to verify that a crack exists.

If you indeed have a crack, the oil should start showing up again.

If so, drain the oil. Easy enough to do.

Then reclean the area. When thoroughly dry, apply some 3M weatherstrip adhesive to the crack area. This stuff is tough and stays put. Give it a day or two to dry. Then apply a second coat. And maybe wait again and apply a third.

Exterior application of a sealer like this won't stand up under much pressure from the inside. But there should be none. You can assure this by cleaning out the vent. It is located on top of the right side of the axe. It screws right off and probably is plugged, if it has never been cleaned. This will relieve any heat generated pressure in the axel, which will also help prevent lube from pushing through the seals.

The only pressure you will have is the inch or two of liquid column pressure from the crack being below the top of the fluid level. This is so minor that the 3M product should hold against it. I like using it in situations like this because when using it for weatherstipping, is gets everywhere you don't want it and doesn't come off (except with the 3M adhesive remover). It is tough and flows real well, too well sometimes.

Refill the axel. When I recently refilled mine, the leak in the front seal almost completely went away. The reason is, I think, because I was very careful to only put in as much oil as the book says. This is about 3/8 to 1/2 inch below the bottom of the hole. If the old grease monkey method of "fill it 'til it runs out" is used, the axel can become very over filled and create too much liquid column over the seal height, constantly forcing oil out the tired old seal as the car just sits in the garage. Check your book for the quantity, and use a pump to get it in, being careful to keep track how much is going in. Most oil bottles have some sort of quantity calibration on the side.

Best wishes on this. Let us know how it goes.

[ 03-11-2004: Message edited by: Brian N. ]</p>

 

[piman]

Hello Lance,
most rear axles have a breather on top, which if blocked will, tend to cause leaks. If the casing is cracked then I agree that a chemical sealer should give good results. Just be sure the breather is clear as otherwise the axle pressurises.

Alec

 

[John Loftus]

Lance,
Just would like to add to the good advice above ... if it does turn out to be leaking from the pumpkin gasket use the blue Hylomar gasket sealer on both sides of a new paper gasket and both metal surfaces. The stuff works great. If you do find a crack you could try using a urethane windshield adhesive to plug it. This stuff sticks better than anything else I have found. A local windshield shop sold me a cartridge for $10 which I used to install my roll up windows and then I found all sorts of other uses for it. Just make sure to wear latex gloves during installation because the stuff is extremely hard to get off anything it touches.

Cheers,
John

 

[LanceLyon]

Thanks for all the advice and ideas. The first thing I will need to do is check to make sure the breather valve is free; that's something I hadn't thought to do.

I'll get into it this weekend and let you all know what comes of it. Thanks again.

 

[LanceLyon]

Good Call, Brian!

I had noticed the bracket was crooked, which is why I thought it might be bolted from the inside. (come to think of it, that would not be a good idea since the nut could come loose and gum up the works!)

It had in fact been bent by something at some time in the past, which had cracked the case. The breather was free, and since it only leaked when the car had been run, I raised the car and ran it with the wheels off of the ground. The movement of the gears inside would throw the oil to the crack and allow it to flow. I had to clean it up a couple of times before I could apply the adhesive/sealant since the oil continued to flow for quite a while after I ran the car. I'll put another coating on tonight before I put the patch to the test in a couple of days.

Thanks for the help!

 

[Pete Haburt]

Lyon;
Mine leaked there also, had pinhole corrosion where the bracket was spot welded.
I cleaned with thinner, smeared some E6000 adhesive sealant on it, and havn't seen any oil seep out in 5 years.
Pete H

 

[LanceLyon]

Thanks everyone. The adhesive has worked. At this point I have two coatings of it on and the leak has stopped.

When I get to the pont in my project where I do the complete body-off restoration I will weld the leak. For now I am having fun getting things in working order so that I can drive and enjoy my toy for a while before getting really serious!