Hey guys. As you can see the underneath of my 4Runner is pretty rusty. I noticed the other day I've been leaking oil from the rear differential for a while now. I think it's about time I put the 4Runner to rest (because of all the rust) but while I look for something new, I'd like to make sure the oil in the differential is topped off. Can you tell me how to add oil to this thing?

thanks.

 

Unscrew the large bolt on the back of the differential and fill it up with gear oil. It should take around 2+ quarts if nearly empty.

 

Thank you!

 

Being this is rusted getting the fill plug out might be very interesting..

A shame you didn`t get after this sooner.

 

I agree Wyoming. I haven't attempted getting the plug out yet and not sure I should. What do you think?

 

Does not take much to round off the fill plug .

Then it becomes a real project.

This is one of those Catch 22 things

All I can say is clean things off . Wire wheel on a dye grinder by hand if it is the only choice.

Spray with your penetrating spray of choice. perhaps a few times over a few days

6 point socket .

Pray to your God or Goddess of choice or not!!!

 

Wyoming9, sorry to jump on this late but I am also experiencing a similar issue. To get up to speed, my differential (01 4runner) had a slow leak somewhere on the back side. So I changed the diff fluid completely, using new toyota gaskets for the drain and fill plugs. After completing, I wiped everything off as best I could and took it for a spin. Came back and parked with cardboard under diff and let sit overnight. In the morning I had no drips at all on the card board. Then I drove to class and fluid appears to be slowly leaking from the same place again. Any thoughts?

 

It could be leaking where the diff bolts to the housing. If you're positive you installed those crush seals correctly. It could be leaking up at the pinion seal and running down. Any wetness on tires to indicate axle seals?

 

Clean things off real good .

Try and figure where it is coming out

As the gear oil gets warm it gets thinner andwill leak out faster.

Not sure just what year but to meet EPA fuel guide lines that section of the housing is much thinner then they used to be. Getting the truck lighter .

From The Liquid brine and other winter chemicals it is possible the housing is starting to rust through.

From what I have found it does not seem to happen all that much.

 

Luckily there is no wetness on the tires to indicate axle seals. Less lucky is that fact that I really think the housing has rusted to the point that it very well may be coming through. Neither of the plugs are leaking and neither is the front side gasket.

 

Thank you for the input though.

 

Use simplegreen or any de-greaser to clean it completely when cool, let it dry off and then add talcum powder to the diff housing. Drive for 30 minutes.......then take a pic of what you see and post 'er up.

 

I will definitely give that a try later this week when I have time to determine exactly where leak is coming from. For now, it's just a drip so I'll make sure that the reservoir is full until I can come up with a permanent fix.

 

I have determined that the housing is indeed leaking through. About half way up to the left of the fill plug. I'm worried that welding could just make things worse if the housing is already thin. Any suggestions on fixes?

 

clean it off with a wire wheel. take for a spin and locate where the leak is from. its probably a pin hole rusted through. drain oil, clean off and mix up some jb weld and patch it. re fill with oil when dry. I waited over night.

mine did the same thing 3 months ago.

no leaks since.

 

I'm thinking JB weld will be the next try for a solution. I had put some permatex gasket maker (specific for gear oil) but the leak appears to be a bigger issue than that. So I'll have to get that off as well. I will try to post some pictures once the job is completed.

 

Also make sure your vent is working like it should.

You don`t want any extra pressure in there pushing gear oil out.

Just where are you. in the Rolling Hills of the Commonwealth??

 

Oh boy, looking at my bio I've got some updating to do. I'm from Northwest PA. I bought the 4Runner just north of the Maryland border. However, it's no doubt seen some road salt in its day.

 

Just an update in case anyone else is experiencing this issue.

I now have two separate batches of JB weld on the rear differential. It has significantly slowed the leak.

It has been suggested that I try "Seal All" to hopefully finish the job and I will be doing so shortly.

Still overly frustrating that the rear housing
A) Does not bolt onto the rear of the axle housing w/ a gasket
B) Was intentially made thinner to meet a standard

 

Being the differential comes out the front of the housing

It would not make sense to also have the rear cover removable

I hope this fixes it.

It is much cheaper to just find another housing if you can`t weld yourself

Till you pull the axle housing out strip the housing and do the prep work weld a new cover on put it back together .

The time does add up .

Plus the added expense of new U Bolts and other hardware brakes etc .