Rust in rear differential

[JQ-72]

I just got this 72 4X4 frame for a build. It has been sitting outside for a while. I pulled the inspection plate to make sure it had a posi in it that was listed on the SPID. When I pried the cover off, about a cup of water came out, then oil! Looks like the bottom side of the carrier and ring gear sat in water for some time. Gear doesn't look pitted too bad. Does this look to far gone to run like it is? What's the best way to clean all this out without a complete tear down. Pictured is the worst side, other side looks OK. Thanks for any help.

[Redneck Rydes]

When I tore mine apart it looked like that, I did not run it, if you do,it will not last long,looks like a total rebuild is in order,cleaning and putting oil in it will NOT help it, ring gear is pitted,bearing are gonna be trashed,check out a reputible rebuilder,and get a price,might be cheaper to find another rear end,sorry.Just my 3 cents

[57taskforce]

What do the bearings look like? I’ve run worse looking gears than that for sure.
Edit: I guess I should be more clear and say that I cleaned up the rust before running it, not just throw oil in it and let it eat. I was talking about the pitting in the mesh surfaces being worse.

[68Gold/white]

Anything is possible, but post 2 is best advice...

If you have at least an inkling of trying to run it, you really need to pull the carrier from the housing. Make sure you keep the caps and shims seperated to put back in same sides...

The bearings (post 3) are what you need to be most concerned about....and the pinion bearings,and of course axle bearings...

If you had a way of setting just the rusted part of the gear in some CLR, or toilet bowl cleaner to get that rusty crud off, THEN you would know how good your gear really is...or not...

Then there's the question...is the inside of the axle housing in same condition???

[special-K]

The No-Spin may be fine. Disassemble and inspect. If it's not usable they are still good for parts. I need one good for a few parts myself.

[JQ-72]

Thanks for the input so far. I’m thinking the bearings should be OK since the water was in the very bottom of the chunk. It’s like the ring gear and part of the carrier was dipped down into the water, but the water level was not high enough to get in the bearings.

[Grumpy old man]

That looks like it's seen it's share of mudding and left to sit ? It needs a total rebuild . Anything short of that and it will fail .That's some pretty heavy rust scale so theres no quick cheap fix on that one .

[Shaky]

You might - might - get away with a lot of flushing if you want to avoid any teardown. I would:

- use a scotch brite pad and smooth the rust on the gear contact surfaces as much as possible;
- spray it down liberally with carb clean or wd-40 or something. Several cans;
- clean all the crud out of the bottom of the housing;
- rotate the pinion down, fill with 10-weight oil (ATF, MMO, air tool oil) and rotate by hand;
- drain and remove crud;
- put cover and gasket on, fill with 10-weight and spin as fast as you can for a while;
- drain and remove crud;
- fill with gear lube, run lightly in truck for 100 miles;
- drain and remove crud;
- repeat with increased miles each time.

Lotsa work and it will depend on how much crud went through the bearings and what it did. Background: I messed with a lot of helicopter gearboxes for a lot of years and saw some gear distress get better and some continue. This is a crap shoot...

[HO455]

PYou have two options clean it up as best as possible without disassembly or full tear down and repair. Once you start tearing it apart there is no good way to reassemble with it half cleaned up. Wipe it down and flush it out replace the cover and run it 50 or so miles and repeat as necessary until the oil looks good when you drain it.
Be aware that it is on borrowed time. I wouldn't take off cross country with it unless I had a spare axle in the bed and the tools needed to swap it.
I would never do this with a Ford 9" as there is no C-clip to keep the axle in the housing when the wheel bearing fails.

[saxart]

Originally Posted by Grumpy old man

That looks like it's seen it's share of mudding and left to sit ? It needs a total rebuild . Anything short of that and it will fail .That's some pretty heavy rust scale so theres no quick cheap fix on that one .

Agreed. If you think about it, the minute you start running that axle, it's going to start dropping small rust particles in the oil. Once that happens those rust particles are going to chew up your bearings pretty quick. Bite the bullet and either get it rebuilt, or source a different axle for the truck.