Rear wheel bearing diagnosis

[bbgot]

When I bought my 02 CC a couple months back, the passenger side rear axle seal was leaking, so I replaced it. It held and didn't leak until last weekend when I put about 600+ miles on the truck. The leak was small and it only leaked when I drove for extended periods of time. When the truck sits, there is no leakage.

I checked the axle vent and made sure it wasn't plugged and forcing oil out of the seal and replaced the seal again this week. I just drove 300 miles for work today and its leaking again!

The axle shaft and bearings looked fine and there is no noise or vibration while driving. Could the bearings just be worn and allowing the axle to move a bit while driving? How do I check for this?

On a positive note, I'm now a pro at taking out the axle shafts (less than 15 minutes last time)!

[HenryJ]

Could the bearings just be worn and allowing the axle to move a bit while driving? How do I check for this?

Jack up the rear axle and support it on stands. Use a bar to lift the tire. How much upward movement is there? Enough to exceed the range of flex in the seal and allow it to leak?

[ckholloway]

Also make sure you are using a good seal. We all know you can buy seals on the cheap but that doesn't mean they work right. National, timken, CR, or original equipment GM. These are the products should be using.

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[bbgot]

Thanks for the replies.

I'm going to take a closer look at it tomorrow when I have some time. Both seals that I've put in it were O'Reilly house brand seals (MasterPro I think?), so If I can't find anything wrong with the bearing, I think I will go get a better brand seal. Although, I would think that even a cheap seal would hold for more than a few days.

[ckholloway]

Brule I'm sure will back me on this. Don't I repeat DON'T use cheap parts unless you have no choice. This will always come back to haunt you in the long run. And to answer you question, no it doesn't have to last for more then one day. They may hold the specs for the manufacturer but there tolerances are not close enough to make a good product. They only have one goal (especially on seals) and that's to sell the product. They don't care if it comes back on them because a seal is easy to say "installer error" if they leak. Trust me on this one, you want a good name brand seal.

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[killian96ss]

Yes there are cheap poor quality parts out there that you should stay away from, but from my experience almost all axles seal that leak right away are due to improper installation. There was a topic on axle bearings around here recently where I explained how to properly install seals so they wil last a long time. Most seals are damaged when you slide the axles back in because the axle was not properly supported, lubricated, or because small burrs on axle cut the seal.

Steve

[bbgot]

Well, I got a chance to take a look at the truck. The axle and bearings are fine. There is very little play in the axle (1/32 in.) I went and put in a Timken seal, so I guess I'll see if that fixes the problem. Again thanks for the advise everyone.

[F9K9]

Timken is a good choice. Please keep us updated.

[LoneWolf04]

When you removed the seal you didn't happen to score the axle tube with whatever you used the remov the seal?

[bbgot]

I didn't scratch the inside of the axle tube and I used RTV sealant on the outside of the seals. Also I verified that the leakage was from the seal between the axle and rubber and not from between the seal and the axle housing.

Thanks for the suggestion though.

[ckholloway]

I didn't scratch the inside of the axle tube and I used RTV sealant on the outside of the seals. Also I verified that the leakage was from the seal between the axle and rubber and not from between the seal and the axle housing.

Thanks for the suggestion though.

I'm not trying to pick at you, but those seals are designed to be use alone. Not with rtv. Even if its not causing the issue of leakage now, it could cause other issues later


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[bbgot]

It was only a VERY thin film of RTV. I was just trying to eliminate any possibility of leaks other than from the rubber seal itself. I know they don't require it, but after three seals, you will try just about anything to keep from having to do it again.

Also, no leaks yet, but I'm going to put about 350+ miles on it this weekend so I should know if its going to hold. Long trips have been when the previous seals have failed.

[ckholloway]

Good luck

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[killian96ss]

Using a little automotive silicone in the outside of the seal won't cause any problems and is much better than using nothing. I've been doing this for a long time on many repairs and complete rebuilds.

Steve

[roadrunner]

Using a little automotive silicone in the outside of the seal won't cause any problems and is much better than using nothing. I've been doing this for a long time on many repairs and complete rebuilds.

Steve

Make that two of us. In my case for 40+ years. Years ago some of the Ford dealership seals did not have any paint or other coatings on the outside edges of the seals just metal. This made some kind of sealer on the outside of the seal not only a good idea but in most cases a necessity.

[F9K9]

Using a little automotive silicone in the outside of the seal won't cause any problems and is much better than using nothing........

X3

[bbgot]

Just an update

Since I installed the last seal, I have been only making short trips with the truck with no leaks. (Less than 15 miles at a time). But today I put about 80 continuous miles on it and the leak is back!

I give up! I'm going to take it to my mechanic after thanksgiving and have him take care of it, this is rediculous.

[F9K9]

Toss it up on jack stands, on level ground, block the front wheels, remove your rear wheels, start it up and place it inDrive. Now, walk to the rear and observe your brake calipers. If, they are moving any then you have bent axle shafts and that will take out seals ASAP. Don't ask me how, I know.

http://youtu.be/fpTluIUVfEU

[bbgot]

Thanks for the tip.

I just tried that this morning with the tires on and off. No visible wobble to the disc or wheel.

So here's my best guess...

Bearings are good.
Axle shaft is straight.
The seal only leaks during extended driving, on short trips its bone-dry.

It HAS to be an axle vent issue causing the axle to pressurize and push out oil. I verified that the plastic vent that is mounted to the underside of the bed is free-flowing when this problem first started. Now I'm thinking the steel vent nipple on the axle must be plugged.

[F9K9]

You might be on to something but, did you look at the calibers when it was in drive? That's the easiest way to see movement. Pull the vent hose off of the housing and see if a straightened paper clip will go through. I don't see it being clogged but, it's a possibility. You're sure that the hose is clear and not just the plastic end attachment?

There's always just pulling the hose off of the diff next long trip (dry) you make and see if, that solves it. If, you over filled it, it would have puked it out of the vent hose before blowing the seals. I've had that happen when overfilling due to an aftermarket diff cover or if you back up onto ramps to fill it and leave the front end on the ground.

[roadrunner]

Plugged vent tubes don't happen often but I have run into it a couple times or so in the past working on other people's vehicles.

[HenryJ]

I can honestly say that I play the three strikes rule and I hate to strike out. I bailed on my stock rear differential pretty fast and upgraded to the ZR2 rear axle assembly. Keep that in mind before you invest too much time or frustration on the stock rear axle assembly.

I don't know how many miles are on your truck and what the condition of the rest of the seals and bearings might be. Take it all and the availability of a replacement in consideration when you plan the next move. The upgrade is well worth the investment. It is a much beefier axle.

[bbgot]

Again, thanks all for the replies.

I ran a piece of baling wire throught the vent nipple on the axle and it didn't seem to have been clogged. Also, just for grins, I put my vaccuum pump on the axle vent and the axle housing holds perfect vaccuum (meaning the seal is just fine with the truck sitting). I disconnected the vent line from the plastic vent valve and wired it to the frame, then drove 60+ miles with it and no leaks.

I'm going to put over 300 continuous miles on it on Thanksgiving day, that should reveal any leakage again. If it continues to leak, I'll take it to my mechanic.

Henry, if I come across a ZR2 axle locally for a good price, I'll do it. But, this truck is in excellent condition and the factory axle is 3.73 with a perfect G80 gearset, so it would have to be a pretty good deal for me to jump on it.

The leak is a small problem, it's just frustrating that something that is usually so simple to fix has turned into such a headache.

[bbgot]

Well, the axle is still leaking on longer drives. I'm just going to have to put in on the back-burner for now until I get some more time to mess with it. I'm just going to be driving it back and forth to work for the next couple weeks. I think I'm going to replace the wheel bearings and seal all at once when I get the time.

In the meantime, I've got an alternator to replace. Mine's still functional, but the internal bearings got very noisy with all the miles I put on it last week.

[HenryJ]

See if you can find a junkyard AD244 alternator. Best bang for the buck and better bearings.

[bbgot]

Ok, I got the dial indicator out and got some detailed measurements.

With the indicator at the outer edge of the wheel, there is only 0.010" of movement while turning the wheel.

With the indicator at the outer edge of the brake disc face, there is 0.003" of movement while turning the disc.

With the indicator on the bottom edge of the axle flange, there is 0.0005" of vertical up/down movement.

With the indicator on the side of the axle flange, there is 0.0015" of horizontal front/back movement.

These all seem plenty tight, I've had perfectly good axles that had much more play in them than this and had no leakage. I'm going to replace the seal one more time and see what happens, if it leaks again I'm going to take it to my mechanic and let him deal with it.

[HenryJ]

Did you check vertical movement during load and unload? This needs to be done with the drum removed as the parking brake shoe may interfere.

[bbgot]

I did remove the brake disc, but I'm not quite sure what you mean by checking under load and unload?

[HenryJ]

Up and down with pressure applied.

[bbgot]

Ok. I did that by prying on it up and down with a prybar. I'm going to try a delco seal after Christmas and Ill let yall know how it goes. Thanks for all the help.

[bbgot]

I replaced the seal again today. I believe I've found the cause of the leak. There was a slight groove that I had not previously noticed worn on the axle shaft where the seal rides on it. I polished the area with emery cloth until the groove was almost unnoticable by feel. I also installed the seal slightly outboard of its intended position to get it to contact a new area on the shaft. Hoping this will finally stop the leak.