So as part of my new life campaign to stop procrastinating I have decided to finally fix my slow leaking differential on my 91 4runner 3.0 4x4 after years of putting it off The leak appears to be coming from the seal facing the front of the truck where the 10 or so bolts are. Looks pretty strait forward from what I can see but I wanted to know if there are any other parts I should pick up and replace while I'm in that deep? My truck will also need a brakes pretty soon so I am going to combine the projects. So far my parts list looks like this.

Front brake pads and rear brake shoes (needs that anyways in a few thousand miles)
Rear wheel cylinder rebuild kit
brake fluid/bleed brakes
gasket for circular bolt pattern diff area
possible lunch box locker (May throw that on while im in there)
front and rear diff breather extensions
Gear oil

Anything else you would suggest while I'm in there?

 

i would also like to know.....

:subscribed:

 

i wouldn't use a paper gasket for the diff. I'd just use permatex sealant on it.

 

Does it even use a gasket? I assumed thats what sealed it but I could be wrong.

 

what diff are you talking about. the front i'm assuming. it's an easy job. just use some red rtv to reseal the cover.

 

I've heard a diff breather could fix a leaky diff

 

I'm talking about the rear.

 

ok even easier. i'd still use rtv to seal the diff to the housing. no gasket there.

 

When I swapped out my rear third a month or two ago, I used black permatex rtv and it was fine. It took me two tries though.

The first time i didn't use quite enough sealant and I left bits of the old paper gasket in place. The second time, I completely scraped away the old paper gasket, cleaned the mating surfaces with acetone, and painted a thin, uniform layer on the mating surface on the axle housing. Properly torqued the nuts/studs and it doesn't leak at all. The RTV is pretty gooey stuff. If you just spread on a thin layer, as thin as you can, but uniform, i don't think you'll be using too much or too little.

There aren't any parts I'd replace while doing it.

 

how so? You mean if the old one was clogged?

 

Here is a pic of said leak.

 

So the leak suddenly got worse after washing my truck and hosing off the undercarriage of my truck, I wonder if that's what prompted the leak to get worse? So it sounds like the differential is sealed with RTV sealer?

 

Get some rags, brake cleaner, any kind of silicone ( i like "the right stuff"), and new gear oil.

Drain gear oil..

Pull the 4 nuts off that hold the axle shafts to the houseing, slide the axles out a little ways. i don't have to mess with my brake lines, cause there is enough flex in mine.

Pull the driveshaft, and the bolts that hold the 3rd member to teh houseing.

Pull third member out.

Scrape off all old gasket material off the housing and the third member, and use the brake cleaner to remove any oil on the surfaces.

Apply rtv all around and bolt it back in..

 

Am I going to need new seals/gaskets for each side of the axle near the wheels?

Also, is there a seal/gasket I need that goes between the diff and the driveshaft?

 

i wouldn't rest the axles on the seals at the ends of the housing. i would pull the axles all the way out. otherwise you may find another leak soon. the downside is that you will need to disconnect the brake lines. get a couple of plastic vacuum caps and put them on the ends of the lines so the brake fluid doesn't pour out. you should bleed you brakes at the end. after both axles are out disconnect the driveshaft and unbolt the diff and pull it our. all you need is a nice bead of rtv and put it back on. it looks like someone didn't use anything on yours. that's a big leak. gear oil is pretty thick so it really needs some pretty open passages to leak like that.

 

So from what it sounds like I dont need anything else besides the main gasket? Does my truck have the 7.8 axle?

 

If and when you remove that drive shaft dont forget to mark it so you put it back on the same way it came off. The drive shaft gets use to being bolted in that same spot so if you bolt it up differently than it was before it could cause some unwanted vibrations. I always put a notch on either ends of where it disconnects and then just match up the notch again when putting it back. Easy! I saw that you posted about this later and I chimed in on it. Get that done and you'll be glad you did it and wont have to worry about it for a good while.

 

I plan on selling the vehicle soon so I'd rather just do as little as possible to stop the leak without investing a lot of time and money. will the gaskets and seals, etc be ruined after I take it all apart? Also what exatly did you replace? when I look in my manual it looks like there are about 5 or so parts on each side of the axle that are replacable. Rings, seals, gaskets, etc.

 

no main gasket, just rtv, if you really want you can replace the seals at either end of the axle housing. Those would be the only seals you need to buy.