Dana 20 gear oil coming out of the vent tube

[GloNDark]

I have been driving my 70 for a while now after an almost year long build. Suddenly last week, my Dana 20 is puking fluid out of the vent tube. I have a rebuilt, resealed Dana 20 with the Advanced adapters extreme output on it with a 2 foot long tube going up to a filter that is mounted on the firewall. Checked the fluid level and it seems fine, not overfilled.

Never had fluid in the tube before. Have had it on the road and on the trails numerous times. Last week took the Bronco to pick up my daughter from her last day at school. Approximately 2.5 mile round trip at about 45 mph.

 

[DirtDonk]

Well, that’s interesting. OK not really…
I was going to ask if this is a C4 swap, and if automatic transmission fluid might not be filling up the transfer case. But you said that the level actually looks OK.
So when you pull the fill plug out of the side of the transfer case, nothing comes out? Or very little at least?

 

[GloNDark]

I just swapped in an NP435 about 6 weeks ago. Has been working fine since. When I pull the t-case fill plug it drips but nothing substantial comes out.

But I was thinking this morning. I did installed a rubber boot over the top of the NP435. I bet that is my issue. The NP435 is now probably "venting" thru the seal in the adapter into the T-case and causing more pressure. I am going to remove that boot after work today and see if the problem goes away.

 

[WILDHORSES]

Head scratcher for sure. Keep us posted. Might be a glitch in the Matrix.

Jim

 

[GloNDark]

Took the rubber seal/boot off the NP435 and still having the issue. I am going to yank the t-case and change the seal in the adapter. That's the only thing I can think of at this point.

 

[DirtDonk]

What kind of seal/boot thingy are you talking about? A top cover over the entire trans? A boot to seal off the body area around the shifter? Or something else entirely?
Did it cover any venting ports on the transmission?

It just does not seem to act like anything "normal" (what is normal anyway?) where your t-case is not over-filled, but you have oil literally pushing itself up the tube. Is it getting all the way up to the filter on top? Or is it just that you can see it climbing a little bit in the clear tubing?
Seems like something is "throwing" it up to the vent, but even that should not normally (there's that word again!) push it up the tube.

Just to be sure, you're triple-sure that it's not in 4wd at the moment? Even that should not do what you're experiencing, but at least that's another avenue to look down.

Paul

 

[GloNDark]

I put one of these under the shifter boot to help block out some of the gear oil smell. I double checked the top of my NP435 and there is no vent tube on it. It appears to only vent out the shifter tower I guess.

I don't seem to have any issues in 4 wheel drive and slow driving. It always happens after being in 2 wheel drive and driving for a period of time. Last night we drove it to town to get pizza, about 14 mile round trip with a top speed of 45. About halfway home I could smell the gear oil and when I got home the vent tube was dripping oil. I slid under it and pulled the fill plug on the tcase and nothing came out.

 

[DirtDonk]

I put one of these under the shifter boot to help block out some of the gear oil smell.

Hmm, I've never had an NP435 smell of gear oil. I wonder if you were already suffering through the beginnings of your gear oil in the vent tube prior to the boot install?

I double checked the top of my NP435 and there is no vent tube on it.

I could have been wrong then. I thought even these transmission cases had a small vent opening/valve. Maybe it's just a hole in the tower after all. It is the highest point in the gearbox, so not out the realm of possibility to find one up there. Just had pictured in my mind one of those old-school vents with the floating cap on it. Our Ford top-loader style boxes simply had a hole punched in a dimple in the top cover. The gasket acted as the baffle in those cases.

I don't seem to have any issues in 4 wheel drive and slow driving.

I mentioned 4wd in case it was in HIGH range. You can still drive on the highway, but you have more stuff spinning around inside there.
Then again, whenever mine was in 4-high it was always accompanied by more gear whine. So not hard to tell you're in 4wd on the road in those cases.

Paul

 

[GloNDark]

Hopefully the final update on this one.

I pulled the t-case replaced the seal in the adapter although it looked fine. Reinstalled and refilled. Drove it around still getting fluid out the vent tube. I ended up getting a bottom drain oil catch can and installing it on the firewall. It's about 7" long and 2" diameter with baffles and so far so good.

 

[DirtDonk]

Has any oil made it up to the catch can yet?

 

[GloNDark]

Yes there is oil in the catch can but atleast now it drains back down to the t-case instead of puking down the firewall to the frame and ground. haha

 

[DirtDonk]

A win for sure!