Very low oil in transfer case - Next steps?

[bugman-74]

Hey guys,
Just drained the oil out of the t-case on a new-to-me '99 SR5 5speed, and found it was very low - about 13oz (less than 1/2 quart). No scary metal chunks or shavings, but some fine stuff - roughly what I would expect from a healthy unit to be honest...

I assume the bearings (among other items) aren't too happy. So the question is what to look for, and what definitely needs to be replaced? I'm very mechanically inclined, and plan to fix this the right way.

 

[cashmoney]

If it's not leaking I'd fill it back up and just keep an eye on it.

 

[bugman-74]

It didn't appear to be leaking, but then it didn't have much in it to begin with.

I would hope no one is dumb enough to not properly fill, so my best guess is that it could have a leak.

I'm in the process of pulling the trans to do the clutch, so its coming out anyway.

 

[jeremyc74]

Fill it back up and drive it. A transfer case isn't like an engine, where low oil will cause a loss of pressure and ruin it quickly. They're designed with a pretty wide range of acceptable fluid levels in mind, and the fluid is also part of the cooling mechanism. That's intended to handle the worst case scenarios (crazy stuff like towing at max capacity in 4WD in Death Valley in the middle of the summer), and the truck has probably never seen that. It's unlikely you've done any damage at all.

 

[cashmoney]

In that case it couldn't hurt to rebuild it. And you'd be surprised by the ignorance of people when it comes to their vehicles. Especially the fluids.

 

[JohnJMonroe]

I would just re-fill it and keep an eye out for leaks. While it was out I would also replace the front and rear output shaft seals.

 

[pluton]

I would just re-fill it and keep an eye out for leaks. While it was out I would also replace the front and rear output shaft seals.

Assuming that there were no symptoms, like leaks, noise or mechanical misbehavior, and that you need to use the vehicle, it makes sense to refill it, and see if it functions correctly.
Unless the OP wished to remove the transfer case just for laughs, of course

 

[BrianSD_42]

Put oil in it and keep on driving

 

[BrianSD_42]

In that case it couldn't hurt to rebuild it. And you'd be surprised by the ignorance of people when it comes to their vehicles. Especially the fluids.

What do you mean by rebuild?

If it is working fine then the only thing he can do by rebuilding it is make it function worse than FINE.

 

[cashmoney]

He's pulling it out to replace the clutch. A fresh set of bearings and seals never hurt anything.

 

[nissanh]

I just finished doing my rear diff and transfer case oil. I am happy as those are full to the max at the time I drain.
Just fill oil and run. don't fix it until something goes wrong, Bearings won't break in a second.
If you plan to fix it, get factory bearings' else don't do the repair because all aftermarket bearings will fail in few years.

 

[csp]

A fresh set of bearings and seals never hurt anything.

And if the seals aren't leaking and the bearings aren't galled or blued from overheating it never helps anything.

This is one of those if it aint broke, don't fix it type of situations.

 

[bugman-74]

I've already got it out (clutch job). It is not my daily driver, so at least I have that going for me. It never leaked a drop in the few months I've owned it, though it looks like it could've been leaking judging by the fine layer of grime on the tcase - but its not soppy wet like I would expect (some of that is just the PBBlaster I sprayed on bolts). The only thing out of the ordinary I found was that the 4mm vacuum/breather tube at the top was disconnected.

Problem is I don't know if it has a leak or not, and I'm already this far into it. I would kick myself if I have to yank this monster again because it indeed has a leak.

 

[csp]

That's just normal seepage you'll find on any vehicle of the age our 3rd gens are.

A leak results in wet oily spots and drips.

 

[Johnnie]

it probably took a decade to get that low refill and forget it

 

[cashmoney]

Unless there's not enough oil left to leak out....

 

[St Runner]

You don't have to pull the whole transmission out to get the transfer case off. Just drop the driveshafts, pull the shift lever and unbolt it. I would just put oil in it and drive it, there are a lot more abused transfer cases driving around perfectly fine. If you are really worried look around for a good used one and stash it until you need it

 

[jeremyc74]

I've already got it out (clutch job). It is not my daily driver, so at least I have that going for me. It never leaked a drop in the few months I've owned it, though it looks like it could've been leaking judging by the fine layer of grime on the tcase - but its not soppy wet like I would expect (some of that is just the PBBlaster I sprayed on bolts). The only thing out of the ordinary I found was that the 4mm vacuum/breather tube at the top was disconnected.

Problem is I don't know if it has a leak or not, and I'm already this far into it. I would kick myself if I have to yank this monster again because it indeed has a leak.

In this situation I might replace the seals, but there's no way I'd tear into it unless you're prepared to buy a service manual and shim kit and do it right. The tolerances that are held during the original assembly process are hard to duplicate in a shop without a lot of expensive measurement equipment and you'll likely end up with something that won't last as long as what you have now.

Seals would be as far as I'd go unless you find something wrong with it.

 

[TheDurk]

It's cleaner than mine was when I did my clutch two years ago, and mine doesn't leak. I do change it every 50k and maybe it is down by the width of my little finger when I do. Sometimes fluid comes out. (Due to temp change, I assume.) Don't go fixing a leak that isn't there. You are probably looking at what is left of a factory fill. Put in some new fluid and drive on.

 

[bugman-74]

Does anyone know how the oiling system works? It appears there is a small oil pump, and the pickup is fairly low in the case. If I knew what was splash/immersion oiled vs. what components received oil via the pump, it might help me exclude unaffected parts - or at least feel better about tearing into it or not.

For the record: before I drained it I could stick my pinky all the way in the fill hole and could not touch oil.

While I possess the necessary equipment and manuals to rebuild this box, I am leaning towards replacing input and output shaft seals (precautionary), and running it. The relatively good condition of the drained oil also makes me hopeful.