Bent rear axle shaft causing leak? (1 Viewer)

[OEMGUY0720]

I’ve changed my rear axle seal + o-ring (driver side) 2x already.
• did not get the the bearing replaced (no play and no noise) bec I don’t have a press as well at home
• no weird noise from the rear driver side acle bearing
• took out the diff breather to make sure the one-way air valve is not causing pressure inside the housing -still weeping
• 2x replaced the oem seals and o-rings -still weeping
• passenger side is bone dry

Is there anyone here that has experienced a bent rear axle making an egg-shaped rotation and causing stress on the seals? If that’s the case, is there such shop that can check true axle rotation? Also, what is a reasonable price from a shop to get that bearing replaced if I bring the rear driver side axle to him?

 

[AlpineAccess]

I’ve changed my rear axle seal + o-ring (driver side) 2x already.
• did not get the the bearing replaced (no play and no noise) bec I don’t have a press as well at home
• no weird noise from the rear driver side acle bearing
• took out the diff breather to make sure the one-way air valve is not causing pressure inside the housing -still weeping
• 2x replaced the oem seals and o-rings -still weeping
• passenger side is bone dry

Is there anyone here that has experienced a bent rear axle making an egg-shaped rotation and causing stress on the seals? If that’s the case, is there such shop that can check true axle rotation? Also, what is a reasonable price from a shop to get that bearing replaced if I bring the rear driver side axle to him?

You can lift the rear axle up and take the brake hat off. Then using a clamp and your caliper gauge, clamp the caliper to the brake dust shield and set it against the hub. Write the number down and then rotate it 90*, try that a few times. It's a rough method but should indicate a bent shaft.

You'd likely be going through wheel bearings with a bent axle, but it is possible. More likely it's a seal that isn't being seated properly, or the axle surface needs to be cleaned and buffed with some Emory cloth.

 

[abuck99]

You can check the run out your self following the FSM procedure by using a dial indicator.

The rear axle beams are pretty stout (till you jump them) but even then, they hold up petty well …just ask @ga12r1

When you pulled the axles to replace seal and O ring, did you notice any wear groove on the bearing race?

 

[JunkCrzr89]

did not get the the bearing replaced (no play and no noise) bec I don’t have a press as well at home

8/10 chance that’s your problem

 

[Malleus]

1. you didn't say what year, so you get my 2000 info.
2. you didn't say what was leaking, is it differential oil or bearing grease? In order to really tell, everything needs to be squeaky clean, like it was when it was on the dealer's lot. When you disassembled the hub, did the bearing grease look like grease (regardless of color) or soup? You did repack the bearings, right?

Here's the FSM take on bearing measurement:

Color inside/outside the cup, or on the roller surfaces, is a dead giveaway though - there should be none.

If you're talking about the driveshaft being bent, this is (schematically) how it's checked:

you don't need a between centers test stand though, it can be done on blocks. And, if you're just trying to find out whether it's bent and not how much, you don't even need a dial indicator; anything that maintains a constant distance above the shaft as it's moved from left to right will work.

If, on the other hand, you're asking whether or not the housing bore is bent out of round and that's causing the seal to leak, you can check that with a dial caliper. Measure around the bore at several positions, (e.g., 12:00-6:00, 2:00-8:00, 4:00-10:00) and compare the measurements; that'll tell you if it's out of round. You don't need machinist's quality dial calipers, Home Depot plastic ones will work. All you're doing is comparing measurements, not validating sizes and those cheap calipers are repeatable enough for that (a good set of Mitutoyo won't hurt, though). I think it's unlikely the housing at the bore is egg shaped, but it's possible.

IMHO, what is most likely is that the seal isn't going in straight. You need a block of something larger than the bore/seal OD pressed against the seal face when it's positioned just on the bore lip; then smack the center of that (a piece of 2x4 will work). If you try to walk the seal into the bore, you wind up getting it crooked.

Another possibility is a deep groove on the driveshaft journal, where the seal lip contacts it. There will be a groove there, even if it's a good journal. If you can drag your fingernail over the groove, it's too deep and the driveshaft has to be replaced. It can be fixed, but it'll be cheaper to replace it.

As to replacing bearings, this is how it's supposed to be done, but that doesn't mean it's the only way...given you can't detect any wobble or noise from the rear wheel, I doubt the bearings are your problem.

 

[JunkCrzr89]

When you disassembled the hub, did the bearing grease look like grease (regardless of color) or soup? You did repack the bearings, right?

The rear axle is a semi float, so the wheel bearings are sealed and not at all serviceable, only replaceable.

IMHO, what is most likely is that the seal isn't going in straight. You need a block of something larger than the bore/seal OD pressed against the seal face when it's positioned just on the bore lip; then smack the center of that (a piece of 2x4 will work). If you try to walk the seal into the bore, you wind up getting it crooked.

The outer seal doesn’t really do anything other than keep dirt out of the bearing area. The inner seal that goes in the housing does all the work at keeping oil from leaking out.

given you can't detect any wobble or noise from the rear wheel, I doubt the bearings are your problem.

It doesn’t take much play to cause the shaft to wobble against the inner seal, allowing oil to leak out.

 

[nissanh]

You must make sure the Oil seal is riding the center of the retainer that holds the ABS ring. The video is a 3rd gen 4runner but same setup for the LC. When I did my 4Runner, had the same problem a leak even with OEM seals. Then followed Tim's Sharpie test and it's been 2 years without a leak.

When you pull the axle again, add some grease into the bearing. The oil that leaked have washed out the grease inside the bearings and could cause those bearing to wear out prematurely.

See 47:50 minute mark and on in this video:

 

[OEMGUY0720]

When you pulled the axles to replace seal and O ring, did you notice any wear groove on the bearing race?

Honestly, the problem is I can’t remember, I didn’t pay attention for any wear groove on the bearing race. Didn’t also took a picture of it when it was out..

 

[OEMGUY0720]

Wow TON of information, I would need to switch to desktop version to read all these information y’all put in. But I appreciate this!

 

[Malleus]

You must make sure the Oil seal is riding the center of the retainer that holds the ABS ring. The video is a 3rd gen 4runner but same setup for the LC. When I did my 4Runner, had the same problem a leak even with OEM seals. Then followed Tim's Sharpie test and it's been 2 years without a leak.

When you pull the axle again, add some grease into the bearing. The oil that leaked have washed out the grease inside the bearings and could cause those bearing to wear out prematurely.

See 47:50 minute mark and on in this video:

You cannot add grease to a bearing that has been subjected to oil contamination. The bearing must be cleaned and repacked.

 

[JunkCrzr89]

You cannot add grease to a bearing that has been subjected to oil contamination. The bearing must be cleaned and repacked.

As I noted above, the rear bearings on the semi float axles are sealed.

Also, the process of removing the rear bearing almost always results in damage to the bearing, which is probably why the FSM says they’re not reusable once removed.

 

[nissanh]

As I noted above, the rear bearings on the semi float axles are sealed.

View attachment 2838990
Also, the process of removing the rear bearing almost always results in damage to the bearing, which is probably why the FSM says they’re not reusable once removed.

you can open the plastic cover with a pick.

 

[abuck99]

Getting the plastic cover off with out damaging it, and then reinstalled where it stays in place is another challenge all together. Not worth the effort unless in a post apocalyptic world where there are no more bearings left on earth

 

[OEMGUY0720]

I think we may have found the problem, gentlemen.

 

[JunkCrzr89]

I think we may have found the problem, gentlemen.
View attachment 2853592

Simple fix if you have a press.

 

[OEMGUY0720]

Simple fix if you have a press.

Unfortunately I don’t. I brought it to a nice guy that does bearings for the local 4Runner club and has given me a ton of information. Hopefully by the weekend it’s done.

 

[OEMGUY0720]

Hopeful that it’s still not a bent axle. Got the bearing and all other things you all mentioned squared to the tee care of a local guy who is a wheel bearing connoisseur.

Old and New bearing:

Took up his advice to use orange toyota fipg for additional seal because of the scores on the axle housing bore (thin amount of fipg applied by hand on the setting corner area of the seal -marked by yellow box)

 

[OEMGUY0720]

Quick update on what I thought was a bent rear axle shaft (egg-shaped motion on the rotation) it wasn’t. It was a bearing issue. As some or most have recommended. 1400+ miles of on-road driving, it’s bone dry as of this writing.

Moral of the story:
• mud is still the best resource for info may it be on paper or actual real life application/experience -invaluable
• it’s possible that an axle shaft “can be” bent, but the likeliness is slim to none, unless its really abused like how and what I did to my Suzuki Jimny 15 yrs ago where we had to bring a spare axle shaft in the trails, but not the LC
• use only original bearings, inexpensive part vs doing all over again
• pay attention to the scoring, that’s your tell tale

Spring of 2022 I will drain and fill new LS gear oil, let’s see what happens if it’ll weep or remain dry.