Rear Diff recently rebuilt leaking axle seals

2000 3rd Gen 4Runner manual transmission rear diff recently blew apart ~150K miles (out of the blue - no warning). Axle seals have been mildly leaking for 15 years. Anyway I had the Rear Diff rebuilt but I recently took it to a dealership (for something else-I go to a dealership once every 5 years or so) anyway they basically told me that there were significant leaks on both seals and that fluid was saturated around the rear breaks and they were shot. quote approx $3K to fix.

Breaks seem to work fine.... but I very rarely hard stop - constantly shift.

Q: if the rear differential was rebuilt surely they would have replaced the seals? No?

I'm not quite sure how all this works - and I obviously don't want another blown rear differential (dealership didn't look at the rear diff fluid level) - I'm not sure what I'm exactly risking by driving it prior to getting repaired - I'll get a local mechanic... Unfortunately I have to take to a mechanics as I work around the country and have no space to keep tools...(also a good excuse as I have metaphorically 2 left hands)

I'll talk to the chap who rebuilt the rear diff Monday .... I'm just not sure what I'm really in for here in terms of scope of repair really needed...

.... the car is pretty much mint - almost zero rust ... so I don't mind throwing a bit of money at it ....

I probably should have just replaced the rear end when the rear diff blew but c'est la vie....

 

Clogged rear breather can cause your fluid to push out through your seals.

 

If they just did the rear diff then, no they aren't going to do the axle seals. From my understanding, that's a whole other job.

 

If the axle seals have been leaking, which well could be caused by a clogged diff breather (happened to me), then you have two separate problems you need to fix/get fixed. The axle seals, and the rear brakes. The rear brake shoes will be saturated with differential oil, making them ineffective. They can't be cleaned, they MUST be replaced with new. I got mine repaired, new rear brake shoes, and new axle seals. The difference in stopping ability is absolutely amazing. I went from stepping on the brake pedal, to gently toeing the pedal, and getting better stopping ability. It took me a while to get used to it, so that I didn't skid the rear wheels, and make the drivers behind me slam into my rear end.

Definitely get both problems fixed. You won't regret the expenditure at all. From then on, check the diff breathers every time you lube the drive line. I do mine every time I go through anything that even might get water/mud/snow/etc onto the drive line, other wise, twice a year. Spring and Fall. When I sold my 87 4Runner recently, which I had owned since 95, it had the factory U Joints, and double cardan joint, still in it. In very good shape,too, if I may say. Anywho, it takes almost no effort to pull the diff breathers, and check to ensure they're clear. A quick puff of air, and voila! It's clear. Slap it back on, and away you go.

Good luck to you!
Pat☺

 

Great info .... do you think I need to replace the bearings (even if no obvious play)

If I didn't fix for a few months and drove it about what's the worst that can happen? I'm not sure

Thanks!

 

Yes. It can never hurt to put new bearings in. They wear over time, and replacing them ensures a good set to run on.

If you drive it, make sure you leave plenty of stopping room. More than if your back brakes were functional. Remeber that you're short a pair of tires, and brake units, for stopping. It will affect your ABS functionality, as well. If the rear brakes never really engage, the ABS system will get confused at the difference between the front and rear brake operation. You push the brake pedal, and the front brakes grab ahold like normal, but with their shoes soaked in differential oil, the rear brakes will never grab ahold with the same force as the front. Thus, the ABS isn't sure what's going on. Which pair of brakes should it take it's information from.

Before I got mine fixed, I tested the ABS on mine. I was going 65MPH, and I came to the turn off I use. There was noone behind me, or in site for several miles in front. I rammed down as hard as I could on the brake pedal, with about 1/4 mile to go till the turn. The truck got the pedal pulse the ABS system causes, but I didn't stop until I was a 1/2 mile or so beyond the turn off. Thankfully, there was a turnout right where I wound up, so I was off the road. I turned around, and went back, being gentle n the brakes. I as able to stop in a reasonable distance, using brakes and gearing.
AFTER I got my axle seals, brake shoes, and so forth, replaced, I tried again. everything worked perfectly. The ABS pulsed the brakes correctly, and I stopped very short, as I expected.

Just my experience with oil soaked rear brakes.
Pat☺

 

Very informative thanks!.... I guess I have one last thought - would you replace the drums or just clean and reuse?

Thanks!

(Mental note when I come back to this thread is to remember to clean rear breather and top up the Rear Differential oil....)

 

I would reuse them. They just don't wear much and are usually very thick material. Of course, use good judgement and if they haven't worn evenly, get new ones.

 

Just did both sides of my axle myself in my 97 for about $250 including the tool to press everything off and on. Very doable just need the tool, press and some hand tools.
I used timken bearings and champion seals.

 

No warning? Lol.

 

I suggest that you do not reuse them. The drums are cast iron pieces and over time will have micro surface cracks. Oil will infuse those cracks with the upshot of reducing the effectiveness of the brakes. I suppose overtime oil may evaporate but why take the risk?

 

There shouldn't be oil in that area and if there was, it gets removed quickly.

I'm not sure who told you that age is an issue with drums but it's not.

More important is if the drums are warped or the shoes were dragging causing uneven wear.

 

Age on its own is not the issue. Emergence of surface cracks over time and having oil embed itself in them (issue of this topic) is. I had a personal not so good experience on a similar matter where the drum was originally not replaced following the repairs made to the differential.

 

Yep I found out this could be an issue so I got the drums done as well ..... I didn't want to have to revisit down the road and I want to keep it going for as long as possible .....on the waffle side of things...... Frame rust is my biggest fear but I've been using fluid film since moving to the NE from NM approx. 3 years ago and will likely try blaster surface shield (which apparently is thinner but much harder to wash off) soon which supposedly is better.... but that's for another thread I guess

 

One other thought. There is a spacer on the axle shaft "circlip" that positions the seal. Without the "circlip" the seal will not function as it should. The first time that they repaired it on my car, the mechanic had forgotten to add the circlip. It soon started to leak albeit at a small rate. They fixed it for good once the dealer figured what the misstep was. Looking at the diagram below I think it is part #6