2000 Limited TRD refresh/repair story

I did notice the pinion get loose after tapping the flange back on, but I ensured that there was no play in anything after tightening the nut. The flange was just as close to the 3rd member as it was before once tightened. I’ve already driven it 15 miles or so, so it’s probably fine, right?

 

Do some figure 8s in the parking lot and listen / feel for any abnormalities. Mine likes to lock up on full right hand turns. Not an issue at all for me during normal driving.

 

If you marked the nut before removal and went back to the same spot, it would pull the pinion back in place, so it shouldn't be a problem.

Is that after the LSD spring upgrade?

 

No, I haven't rebuilt that one yet. I still have the springs. I need to order that bearing kit. I'm not doing gears right now, so I want to swap the 4.08 ring and pinion I have in place of the 3.91.

 

Wait, what? Is it trying to lock up because of your LSD, or because the pinion is hitting the carrier?

 

This

 

Shit. That sounds really bad.

 

I think it’s still leaking. Shoot.

 

Nooooooo!!!!!!!!

 

Yeah, still leaking.


I pulled the flange off and took a look at the seal, and I couldn’t find anything wrong with it. It looked great. It was in there nice and straight. I tapped it in a bit further, but I honestly don’t know what that’s going to do. We’ll see tomorrow if it leaks again.

 

Is there a groove worn in the flange? That can cause new/good seals to not work.

 

Are you seeing coming from the pinion flange, flowing down underneath the 3rd and then dripping on to the ground? I know it's early in the morning for me. Just looks like it's directly under the diff gasket in the pic.

 

There’s a wear mark, but it’s definitely not a groove. I didn’t do the fingernail scratch test when I had it off but I wiped it clean with a rag and it felt nice and smooth to me.

Yeah, it’s running down the 3rd member and dripping from the lowest point. It’s the pinion seal for sure.

 

Still leaking. I bought another seal, but I’m not sure if that’ll fix it. If not it’s going to the shop.

 

So, I still haven’t replaced the seal, but it’s stopped leaking. I haven’t been driving it a ton, but it isn’t wet on the diff, and I haven’t noticed any fresh drips on the ground. There’s absolutely no way all 3.5 quarts have leaked out. I don’t think it would stop leaking if the level of oil in the diff got below the spindle, which I doubt it has.

What do you guys think? Do I swap the new seal in? I still can’t check the fluid level without draining it all and pumping it back in the vent, which is just a pain and messy.

 

Fill er up and see if it starts leaking again.

 

Twss.

 

Yup. Maybe what you saw dripping was just residual? Only way to know is fill and monitor.

 

Yeah, it’s still leaking. Not very much, but definitely still leaking. I’ll throw the new seal in and see what that does.

 

Second new seal and it’s still leaking. And obviously from the pinion too. What the hell! I don’t know what else it would be.

 

Have you thrown a mirror up top to see if it's possibly leaking from up top, rakc up there, or maybe where

I mean, it's feasible the spinning while in motion, and things seeping out and being blown back is coating everything evenly. But I'm curious if maybe it's an issue with the gasket between the pinion housing and axle/diff housing (up top), crack or loose nut on the pinion housing, ???

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I haven’t, but when I’ve been working on it I’ve had it lifted up on stands, and my head has been up between the muffler and gas tank. So, I’ve been able to see the top of the 3rd member, and it doesn’t seem to me like anything is wrong up there.

I’ll throw a wrench on those nuts, but I can’t imagine why there would be a crack in such heavy cast iron.

 

I've literally never seen it in my life, but I also can't explain why else it would happen. I also admit, my breadth of in-depth knowledge on anything past the slip yoke is lacking.

I'm curious if, like @des2mtn or @whodatschrome may have any thoughts. I'd trust either of those guys to get in my rear end more than any local shop.

 

Yeah, in my (relatively short) time on this site I’ve never seen a pinion seal leak like this come up.

Makes me wonder if I could swap out the whole 3rd member for one with an LSD.

 

If there’s a groove in the pinion yoke, then it can tear up a seal pretty quickly. I’ve installed Speedi Sleeves to fix tenacious leaks like that before. They are on the expensive side, so half the time i resort to just buying a brand new yoke.

The pinion gear could also be slight bent when it took a walkabout on the carrier. That would cause a leak as well.

But very first, check to make sure that the axle housing vent isn’t rusted shut. If it is, the housing will build up pressure and cause leaks.

 

I can't remember, but didn't you say you were filling from the breather? How are you knowing if you are over full or not since your plugs are now a permeant fixture? That definitely looks like it's coming from the top of the diff or axle housing.

 

I’d purple power and pressure wash the entire axle really well. Put the back of the truck up on jack stands, sprinkle the entire axle housing with talcum powder or corn starch, put the truck in gear and look for leaks. Also look to see if you can eyeball any runout on the pinion yoke.

 

Yeah, I did the fingernail scratch test when I had the yoke off and couldn’t feel any wear on the seal surface. You can see where it was running for years, but couldn’t feel anything. I could also see that the first seal I installed was riding on a different spot, so I don’t think that could be it.

That photo in this thread of a pinion gear hitting the carrier wasn’t my photo- I don’t think that’s happened to me. I made sure to get the nut tightened down to the same spot to get the bearing preload correct. I don’t know how or why the yoke would get bent.

I’m also doubtful that the leak is due to pinion bearing wear. The diff doesn’t whine, the oil that came out looked fantastic, and I couldn’t feel or see any slop in the bearings.

The vent is free and clean, which I know for sure because that’s how I’ve been filling it. The rear cover is probably pretty thin from rust and I’m worried that trying to open the fill port will crack the cover.

The drain plug is fine, so I’ve been draining out all the oil and measuring it before putting it back in, to get the right amount in there.

 

I went out and looked at it some more. I won’t get the chance to clean it off real real good for a couple days- but I sprayed everything down with brakleen when I replaced the seal again, so none of this is residual.

There’s noticeably more oil on the bottom side than the top side. Which makes sense- but if there’s a leak on the top I’d expect to see a lot more on the topside. I’d also expect it to pool on the ridges in the casting, (red arrow) but it didn’t. There’s definitely less oil towards the rear of the 3rd member.


I sat here for a few minutes and watched oil drip out of here. I guess that this could be coming from above the pinion and flowing down the yoke, but it really seems to me like the pinion is what’s leaking.

 

when replacing the pinion seal, did you clean both the outside of the metal seal and the pinion opening on the 3rd member? Because i like to smear a thin coating of RTV where the seal gets pressing into the 3rd member.

It's also going to be very difficult to get the bearing preload exactly back to where it was previously if you still have that crush spacer...even with a torque wrench or witness marks. That's why some guys install a solid pinion spacer instead.