The truck: 1992 Explorer 4D, 4WD. 203,000 miles.

Problem: The right rear wheel bearing was leaking diff fluid. The seal was bad. I replaced both rear bearings. Within a day and <30 miles the right is leaking worse than before. The left is fine. The old right bearing was also failing. Noisy and lots of metal filings in axle housing. The axle is also pitted about 180 degrees possibly where it rides on bearing. The left axle is pitted but not as much.

I think that whatever was/is going wrong destroyed the old seal and is working on the new one. I replaced the whole axle housing assembly 50k miles ago because the right wheel caught in a snowy ditch and started the housing leaking between the axle section and the differential. I reused the original axles. I believe the axle is true.

It's got to be the axle.

 

It is easy to damage the seals while putting them on and when installing the hub. You need to be sure not to pinch the rubber seal while installing it. You also need to grease it up along with the shaft it will ride on. It helps to cleanup and maybe sand the surface where it will ride.

A pitted axle shaft is probably a lost cause if it is already leaking. Don't know if they can be cleaned up enough without losing the seal.

BTW did you clean out the axle tube and differential? If there were metal bits in there, you need to get them out. I would guess you need to flush out the axle and diff with solvent. I have never had this problem so I can't give much advice on the easiest way to do it.

Good Luck,

Jim Henderson

 

I was gentle when installling the axle but I did have to hammer the bearing assemblies in using a block of wood. I took care not to strike the inner race. The axle housing was cleaned out best I could and I checked the diff housing found no filings but still wiped it out.

I have ordered a new right axle and will replace the left side with the one that came with the rear. That one has no pits.

There is a small play in the right axle that may be enough to lift it clear of the seal allowing leakby.

Thanks for the help. I update when I get things installed.

Reg

 

New axle and still drip, drip drip. About a drop every few seconds.

The seal was fine when the axle went in. The only thing I can think of is the housing/bearing clearance may be off due to damage to the seating surface.

The differential housing cover now leaks as well. With a gasket and RTV and RTV alone.

What is going on?

 

Make sure your breather isn't plugged

 

The breather was clogged. I cleaned it out but the leak is unchanged.

Note: The bearing/seal only leaks when the axle rotates.

 

I have an older 2WD that I replaced seals on, which is much simpler than what you have. To me, it seems there is a number of items on the inside of the differential housing that must seat properly. Is everything (splines, c-clips, lock-bolts, etc,) aligned and seated properly? It seems like if it went back together with no problems and everything is seated well, then maybe the seal is not aligned...if that's the case, you have to try again with a new seal because I think they are only good for one shot.

 

Sounds like you blew the new seal out with the plugged vent. Try a new one. Remember to pack grease on the inner lip to hold the tension spring of the seal in place if it has one.

 

Thanks Gearhead and eckart,

The diff components went back together fine on the right side (leaking side) the left gave me problems due to alignment. The left side splines would not align with the housing hole and gear so I had to insert the axle into the the diff housing then slide the gear onto the splines then manuever the gear back into place. The axle was very stiff to turn by hand.

The right (problem) side went on just fine. Everthing seated.

The manufacturer of the bearing said it should protrude about 1/4 inch. The manual says to seat it. I did. It sticks out about 1/32 to 1/16 inch. The assembly was dipped in gear oil before installation per the vendors recommendation. Grease is not mentioned in the manual or the installation directions.

I know I have to pull it and replace it. I am not looking forward to it. It's become a pain in the &#*! The seal looks fine. I can not tell if the leak is between the outer race and the housing or the outer race and seal.

Thanks again,

Reg

 

So you now have a question to answer: The manual says to "seat" the seal, and the instructions say to allow for a protrusion. Do you want to pull the seal off and try a new one leaving it "protruded" or try seating it again?

That leaves you with some tricky decision-making.

I certainly am not an expert, so take what I have to say as coming from a greenhorn. With the bearing and seal I last replaced, the seal definitely had a seat and that's where I pressed it...totally against the seat. It held with no leaks. This was a Ford set-up with the seal BEHIND the bearing. Your seal is probably in front of the bearing.


(Edit)

Did you say the seal was seated? If so, check the height all the way around, it should be the same with no deviation. I guess its possible you could have the wrong seal too. I guess I believe that a seat is there for a reason, and it definitely keeps the seal in proper alignment. When you go to get the new seal, find out if there is more than one part number...meaning there are more than one design of seal.

Then you have to decide with the new seal whether you want to seat it, or allow it to protrude. Either choice might not have the option of changing your mind.

That tension spring is a real fun item too. Its a little rubber "O-ring" that is wound in a stainless steel mesh which is supposed to keep the seal tight against the axle. It wraps around the backside "lip" of the seal opening. The grease (probably lithium will work) may or may not hold the thing in place when you squeeze the axle through the seal. If it falls off, good luck trying to get it back on after the seal is locked! This is a form of torture Ford devised as if taking out the axle was not enough.

 

Pulled out the bearing last night. It came right out. I did notice a slight difference in the seal/outer race height. The seal was in farther at the bottom than the top. Hard to see difference.

Anyway, the replacement is now in and it is a "BCA Axle Repair Bearing" which is designed for worn axles or housing.

Difference: Old- had only a seal on the outside and is lubricated by the diff gear oil. New- has in inside and outside seal and is permanently lubricated by grease. The inside seal hugs the axle shaft. The new bearing also suggested RTV between the outer race and axle housing for a better seal which I did do.

So far 80 miles on the new bearing and no leakage.

I don't think so but could there be any problems with different bearings on each side?

Thanks to all,

Reg

 

This might be jumping the gun here, but I believe the whole intent of the "repair bearing" idea was to save the user money by not having to replace worn axles. I think it would defeat the purpose if you were required to replace both bearings.

The technical side: I think the only thing the repair bearing is doing is shifting and re-distributing the bearing wear-pattern to a larger area on the axle. I can't figure that it would have a "bearing" (pardon the pun) on the operation of the differential, such as changing ratios, or anything having to do with the gears and meshing. If I'm off base here, I hope someone corrects me.

Anyway, glad to hear its stopped leaking.

 

You're right - the repair bearing isn't causing any problems.

 

Gearhead,

You are correct regarding the contact area. I knew the bearing would ride in a different area - the drawing showed that. I figure since this is not a Formula 1 car a minor shift in the bearing position won't matter too much. The truck has 204,000 miles. By the time these bearings go bad . . .


Thanks,

Reg

 

My buddy has those 'repair bearings' that ride on the axle just outside of the worn area in his 12 bolt under his Jimmy. He has not had any problems with them. His right side axle was worn also.

DK