Diff Gear lube is being pushed out of the vent tube on Dana 20 rear axle..

[Chipb1]

After putting a 4 inch lift on my 1979 CJ5 , and changing the pinion angle to 21° and installing a double carden driveshaft now I notice if I drive on the interstate, I'm pushing gear lube out of the vent tube on the axle Dana 20 , I can't find anything wrong with the axle. I pulled it apart and bearings all look good.
Has anyone seen this happen before?

 

[TSB8C]

Oil coming out where the vent tube ("nipple") connects into the axle housing? Or all the way up the hose connected at the tube? If leaking where the "nipple" connects into the axle housing, that happens with age where that nipple is pressed in. I have only seen a few rare cases where someone needed to replace those. Get some threaded hose nipples (Edelmann Part #744250 for example) and use a tap (1/8" NPT) to thread the holes in the axle tubes and screw the nipples in. Use grease on the tap to capture the small metal fragments so they don't fall into the tubes. I have also heard (never seen) small 8mm copper tubing glued on with JB Weld if you don't want to cut threads in the axle tubes.

 

[Chipb1]

Nope, it's not leaking at the nipple. It's getting pushed right up the hose. It's coming out and it's blowing all over the fuel tank.

 

[KRUPP]

Might it have something to do with recently rotating the housing more pinion-up?
Where is the vent port on your Dana 20 ?

 

[Chipb1]

Yeah, I'm figuring the front bearing And opinion isn't getting enough lubrication and
causing heat and expansion. I'm changing all the bearings, even though they look good and I'm going to overfill the axle.
Also, it's an AMC20 . Don't know why I said Dana, 20 when I posted it.
Thanks !

 

[KRUPP]

Right. It auto-corrected me when I typed in the "20". I understood what you meant though.

I quickly replaced the 20 rears in both of my CJs, so I can't speak much for the oiling issue. I would bet that you are correct though in assuming too much heat in there. Someone with more experience on those axles will probably chime in.

I'm just spit-balling ideas now, but what about adding a fill port in the diff cover? I don't think 20s came with 'em, but maybe add one at a higher elevation to get the oil level a bit higher. There are weld-on bungs available.

 

[grimmjeeper]

The fill plug is on the housing from the factory. I believe raising the pinion raises the port so filling it until it runs out ends up overfilling the axle.

An over filled axle will spew fluid out of the breather.

In normal driving, the ring gear will carry oil up and over as it rotates, splashing it directly on the pinion and associated bearings. So even with low oil, you still get some on the bearings.

 

[Manic Mechanic]

I'm assuming you have it over filled based on the amount of pinion angle that you have. Personally I'd rotate the pinion back down with pinion shims

 

[grimmjeeper]

When you lift and go to a CV shaft, you need to orient the pinion correctly for the driveshaft.

Just recognize that you need to measure how much gear oil you put in rather than filling it until you get to the higher level of the fill plug.

 

[Chipb1]

My idea was a little simpler, I was going to put a 1/2 inch black 90 right in the fill port, and bring it up to the level, I want it, and put a cap on it.

 

[Chipb1]

I just have a feeling that the front bearing isn't getting quite enough lubrication, it's not showing any signs of heat, but it has to be getting heat from somewhere, and that's the only place that would be getting less lubrication after I rolled the diff.

 

[Chipb1]

Yeah, that is what I did. The rear diff is rolled up to 21°, so it points right at the tail of the Transfer Case .

 

[grimmjeeper]

I just have a feeling that the front bearing isn't getting quite enough lubrication, it's not showing any signs of heat, but it has to be getting heat from somewhere, and that's the only place that would be getting less lubrication after I rolled the diff.

I'm skeptical that there isn't enough oil getting to the pinion. The ring gear carries oil up and over to keep the pinion bathed in oil as you drive down the road.