Rear diff leak
 

The outside of my rear diff on my 99 4Runner is wet with fluid..it doesn't leave any drips on the pavement after i park it. It's a very slow leak but I'd like to address it. Having owned Subaru's the rear diff's just have plugs. Since the 4runner has an axle do the axles have crush seals? Just looking for some help. Thanks -Karl 99 V6 4Runner 5speed with 157k

Hi

Based on your description, it could be the rear pinion seal. Are you familiar with that?

Provided the face of the diff isn't rusted through it is likely the pinion seal as the previous poster mentioned.

You just need a 27 spline pinion seal to correct it, and yes it uses a crush sleeve. Aftermarket solid spacers are available which are superior to a crush sleeve.

Yeah I don't think it's rusted through. It has surface rust obviously for its age. I'm not familiar with a pinion seal however it's something I can handle I am very hands on. I just want to fix the minor leak and change the fluid before I drive to NY next weekend to see my parents. Thanks -Karl

If you live in an area where they use salt it could be rusted through, just replaced my Diff cover this past winter. Noticed a wet area one day and sure enough there were small pinhole leaks, had to weld a new cover on, fixed the issue its like new again.

Good luck, hope yours is just a seal.

Thanks for the replies everyone I am hoping it is something as simple as replacing the crush seals.

It's probably rusted through. You are on cape cod, so that is about as bad as it gets for rust; you're boned.

Click the project link in my signature, I was in the same boat. If the back face of the axle housing is getting wet, then you are either leaking out the fill plug (should be obviously centered on the plug), or you are rusted through. A leaky pinon seal will leak onto the front end of the diff, and a leaky housing seal will drip to the bottom. You are probably leaking through the housing, and it's soaking into all the rust, which is why it isn't just dripping actively.

You can take some spray cleaner and blast all the oil off, then check it again to see where exactly the leak is, or you can just take a twisted wire brush on an angle grinder to the housing and find the pinholes yourself.

I am sorry to have to welcome you to the club...

I will clean it off this weekend I am seeing that people can use JB weld to repair it or stop the leak. Would that work?

The front of the diff is clean...It isn't wet with oil..It's just the back of the diff..but at least now I won't be surprised if it rusted through

You can try JB weld but its a temporary patch in the end it will leak again. I patched mine for a few months but it eventually leaked again as I knew it would.

Hard to get a good bond the cover is so saturated with oil that's the problem.

Check out Barnes4wd, they sell a weld on aftermarket heavy duty cover. That's the route I went and I promise you the Barnes cover will never rust through, it is heavy gauge steel, great quality product!

awesome I will check that out...I'd rather go that route than jb welding it..Thanks for the advice!

I had the same issue on mine- yesterday. First, check the breather plug to make sure it is free and working. My drivers side axle seal was leaking bad which is what led to all this.

When I removed the breather plug it actually made a really loud "psshhhh" releasing all the pressure!!! I replaced the breather plug and checked the diff fluid level removing the filler plug where there was some seepage. The crush washer was shot.

The fluid was down a little, added some, reinstalled the filler plug with a new washer, and cleaned the wheel off to recheck for leaks.

Today, no leaks anywhere. I will still replace the shows and ale seal, but that breather plug!!! Very surprised....

I'll check that out the breather plug too...I bought new crush seals at the dealer today..What would you recommend for diff fluid? I always used mobil 1 synthetic gear oil on my subaru.

I changed my diff fluid today...it was pretty nasty..and there wasn't a crush seal on the fill plug. I cleaned off the diff with heavy degreaser and brush and didn't notice any pin sized holes

Just checked that out, that is a great product. I wish I knew about it when I got mine, though I had alot of rust on the rest of the axle housing too. It certainly would have been alot cheaper though...

Toyota Heavy Duty Differential Cover