Leaking Rear Diff - 2001 SR5

Hi All,

First time poster here. I have a 2001 SR5 4.7 and earlier this summer noticed the rear diff oil was dripping on my garage floor. I haven't had time to get to fixing it until now, but I'm finding it hard to tell where it's leaking from. My first thought would be the gasket between the diff and the axle, but there is oil all over the underside of the diff housing. Question is, could the oil just be seeping out and spreading up the housing? It looks like it's seeping up the axle as well. Could the actual diff itself have a leak in it? From what I can tell these things are very thick walled and it seems unlikely that it's leaking. Just looking for opinions. In the mean time, I need to see if I can even get this thing torn apart...

Most of the oil is on the very bottom near the seal.

Pics -

 

Oh, My !

 

That is not a quick fix. You are better off getting another complete rear end and swapping it out. Where are you from so I know not to buy trucks from your area?

 

Welcome

 

Minnesota, so yea we get all the salt that just eats everything up.

 

That needs to be replaced unfortunately

 

I was afraid that'd be the verdict.

Looking at this site it's looking like I need at a minimum number 2 (carrier case) and number 8 (gasket)? For now I'll probably hold off on the axle and see how long that rear pan will keep from leaking. This isn't my daily driver so I can take my time with this.

 

Look at the good side. Once you sandblast off all of the rust, it will be lighter and easier to handle when you swap it out.

 

How is the frame?

 

Showing it's age, but not nearly as bad as the diff.

 

Welcome. Yikes! That looks scary and I've been dealing with my rusty Toyota since new.

First original shock I've seen worse than mine. But I've never seen a differential that bad; looks like the salt was never washed off.

I've got 235K on my shocks, how about you?

 

Plus, the holes where the fluid are leaking out will probably become obvious!

 

I'm at 140K so yea the engine is great and will run for a long time yet. Probably should replace the shocks while I'm doing this though.

Finally got a chance to start tackling this today and with some heat, elbow grease and patience I got all the housing bolts loose and the drive shaft dropped. Once I get the axles pulled back and the the diff pulled out I'll order the parts.

 

I got the diff dropped today and the pumpkin looks good from the inside which fits with originally seeing the leak on the very bottom of the carrier housing. I can't see any pinholes and neither can my FIL. It feels solid to the touch. There is also a bit of oil still sitting in the bottom so obviously no leak there.

The carrier housing is about 1/2" thick so I can't see how that would get a hole in it. I can't see anything resembling a hole on the inside. Overall the gears look healthy from what I can tell. It's pretty obvious the oil was getting old though, really dark.

The "gasket" is almost non-existent. It's the thickness and consistency of wax paper and seems to be glued or rusted or something to the carrier housing. It flakes off in pieces. Going to just try replacing that and will report back.

 

Pinion seal most likely then.

 

That was my thought too.

The fluid isn't going to flow up from a leaky gasket. It looks like gear oil has been leaking out the pinion seal, then creeping down and to the rear as a result of gravity and air flow from driving.

 

When I first found the leak, there was nothing up near the driveshaft and I never drove it after that. It was all on the bottom of the axle housing. Then the truck sat for 6 months before I took that photo.

It does seem odd that it leaked "up" the housing, but you can see on the axle housing that it is leaking "up" as well.

 

Ahh. Then yeah, gasket or housing. It's just spread over time then.

 

Does anyone know what the torque specs are for the propeller shaft bolts connecting the drive shaft to the diff? This is for 1st gen tundra (2001).

 

65 ft lbs

 

Well I got it all back together and got about 3/4 full with gear oil and it started leaking out of what must be a small crack in the carrier housing. It's plainly obvious where it's leaking although I couldn't see anything when I had it apart.

I called my local shop and with all the labor shortages they don't have the manpower to tackle something like this. So my options are either buy the entire assembly for $1500 and just pop it in or attempt to rebuild it in a new housing. Is it even possible to get the pinion gear and the bearing out without a press?

I would be fun to learn how to do this, just not sure how feasible.

 

Wasn't as hard as I thought it would be. Some light taps with a sledge got the whole thing to slide right out and didn't damage anything except the pinion seal which need replacing now.

 

Mind to snap a pic of where the crack was?

 

Sure, here they are. It was just a little pin prick of a hole until I poke it with a screwdriver. I found it by looking on the inside and saw just a little tiny rust spot the size of a pinhead. All the thickness of this case must have rusted and flaked off.








I've never taken a diff apart and put back together. This one looks simpler than others I have seen in instructions.

Is there any part of putting this back together that is crucially important yet easy to get wrong?

 

So I have the pinion shaft and related bearings moved to the new house. I have it all tightened down would like to check the bearing preload just to make sure it's good. I'm a little nervous I got it too tight.

Anyone know the inch pounds the pinion preload is supposed to be?

 

Looks to be in the range of 9 - 15 in/lbs...



https://www.differentials.com/technical-help-2/set-up-specs/

 

Rear diff of brand new models also seep with zero rust. Toyota thinks it's good for the environment.

 

Thanks, I found another source that said 12-15. I had gotten it to 9 without measuring so went a little further and called it good.

 

Usually you need to measure without the pinion seal installed if it's all new.

Otherwise it adds drag and that number is off.

 

Pretty sure my truck doesn't wanna be driven. Got everything put back together and the oil changed and was gonna take it for a spin but the brake line snapped off when I went to remove the passenger side axle. I had only been sliding it out a few inches and that destroyed the axle o ring and was replacing that. The rigid line was cemented to the threaded nut so it just twisted and snapped.