The back side of my rear wheels are gummed up with some sort of oily sludge. It's also running down the inside sidewalls of both rear tires due the centrifugal force generated as the wheels turn. I just went out and felt around for it. The gunk on the sidewalls of the tires seems to be dried on. The sludge on the inside of the wheels isn't very thick but enough to rub off on my finger. It has a petroleum type smell to it. It's about the same on both sides and isn't a problem on the front wheels at all. Since I've been too busy to take things apart and do a proper inspection, I figured I'd ask you guys for help.

I did check the brake fluid level to see if maybe the brakes are leaking. It looked fine. My only other guess is grease from the rear axle. If that's what it is, what is causing it? It seems to have occured on both sides at the same time which doesn't make much sense to me.

 

My money is on bad Axle seals! Get those replaced, and you'r brake shoes while your at it..since they're now soaked in 75-90.

 

axle seals


your breather is probably clogged migth want to look into that also

 

Go to a parts store, open up some gear oil and take a smell. You will never forget what it smells like. Compare it to what you have on your truck. I bet it is gear oil leaking from your axle seals.

 

Just pull one of the rear wheels and take off the drum.
It will be obvious if it is the axle seal (which I would bet it is).

This might help if you wanted to do it yourself:
https://www.yotatech.com/~corey/tech...m1_oilseal.htm

Also check your diff breather and make sure it is not blocked and forcing oil out the seals (replace it if need be).

 

Kevin,

I'll chime inwith everyone else and say its the axle seals. If you were going to tackle it yourself, you might want to send DarylD a PM, he might be able to help you out with the press work (though it'd be a bit of a drive for you).

David

 

What press work? The inner seals are what is leaking, and they pop out with pliers or screwdriver. You would need a press to replace the outer seal, but that's not what is bad.

 

Agreed. I'm thinking it'd be worth doing both while you're in there.

 

The rear axle seals are a snap to replace on that axle. As Unhappy99 said you just pop out the old one and tap in a new one. I suggest using a seal driver or a nice block of wood to tap in the new seal - helps get it in straight and keeps you from dinging it with a hammer.

 

Does the 98 4runner have CV like axles with rubber boots? If it does you might want to check and see if they are ripped buecause it might be axle grease. The boots can look fine and still have a small rip in them and the force at high speeds can shoot all the great all over your suspension, brakes, tires, etc. I had this happen many a time on my last car, really annoying. Just an idea anways not familiar with the drivetrains of 4runners yet, but I saw boots on my 4runner's front axles but its old.

 

check your vent tube and see if it is clogged up with some kind of gunk if not you will have to ask someone to do the taste test and see if it is gearlube or brake fluid check it out and you will be headed in the right direction

 

Taste test?? i dont think id want to put anything that eats paint (brake fluid) on my tounge. and gear oil has a distinct smell anyways......im having this same problem right now. i just havent got around to fixing it....i did put a quart of oil in the diff tho....it was running dangerously low.