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Gear oil out the vent tube.

Thrown_hammer

Thrown_hammer

Doofus
Joined
Apr 15, 2021
Member Number
3804
Messages
279
So I have an ARB in the rear axle. Jeep TJ Rubicon Dana 44. Today while drivng I accidently hit the compressor on switch while aiming for the overdrive off switch at 55mph. Didn't hit the locker engage switch.

When I get home I notice fluid dripping off the gas tank, and when I looked up in the rear wheel well at first I thought it was gas all over the fill tube, but it was gear oil that sprayed out of the vent tube.

Locker has been in a few months and no leaks of any kind.

Could flipping the compressor on switch while at speed have done that? Or do I have bigger problems?
 
Just jacked the back tires off the ground and verified the locker still locks several times and no oil out the vent tube.
 
140w is too thick, it’s sticking to the roof of that diff and blocking the vent, causing it to be spit out during heat up. No reason to run anything thicker than 80-90w in a diff.
 
and since some might not be aware

Viscosity of gear oils may be stabilized by polymeric additives (viscosity index improvers). Viscosity of such gear oils is specified at both high and low temperature. These oils are called multigrades and they are designated by two numbers and the letter “W” (SAE 75W-90, SAE 80W-90, SAE 85W-140 etc.). The first number of the designation specify the oil viscosity at cold temperature, the second number specifies the oil viscosity at high temperature.
For example: SAE 85W-140 oil has a low temperature viscosity similar to that of SAE 85W, but it has a high temperature viscosity similar to that of SAE 140.
Multigrade gear oils are used in a wide temperature range.
Click to expand...
 
motobilt.com

Jeep Wrangler Differential Fluid Capacity Chart

Here at Motobilt we get technical questions all the time from simple questions to in-depth discussions. One question that comes up often is how much differential fluid should be purchased to fill up a diff. Well the general rule of thumb is to fill your diff up until the fluid starts to run...
motobilt.com motobilt.com

Fluid Type (ALL LISTED TJ AXLES): 80w-90 or 75w-140 If towing
Click to expand...
 
rockyota83 said:
tell that to the racers who run 250w

every diff i own gets 140w, 80-90 is for gear boxes or diffs that hold a gallon or more or get driven by boring grandmas
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Ok, sounds like he doesn’t race, neither do I. Running 250w oil has no business on the street.
 
Mvanhelden said:
Ok, sounds like he doesn’t race, neither do I. Running 250w oil has no business on the street.
Click to expand...
no one recommended him to run 250, it was an example of yes indeed people do run and need to run thicker oil than 90w

pretty much every factory owners manual of any truck/suv will recommend 75-140 gear oil in the rear diff for towing or hard use, i would never run 80/90 in a vehicle that sees towing or hard abuse unless it was what you drive at work that holds gallons of oil and calls for something thinner for mpg


 
i could do this all day

Dana 80 Differential Fluid Replacement & Axle Specs

Dana 80 rear differential specs and fluid change procedures. The Dana 80 is a heavy duty rear axle used in various GM, Ford, and Dodge truck applications.
www.dieselhub.com www.dieselhub.com
Dodge - SAE 80W-90, 75W-140 suggested as a heavy duty alternative
• Ford - SAE 75W-140 full synthetic
• Chevrolet/GMC - SAE 80W-90, 75W-140 is suggested as an alternative to more frequent fluid changes per the C3500HD manual
Click to expand...
 
the bigger axles that hold more fluid get away with the 80/90, the smaller axles need 75-140 for heavy use, you can find this information all over

Rear axle 1,2 Motorcraft SAE
75W-140
Synthetic Rear
Axle Lubricant
F-250 /350
(10.50 inch
axle
Click to expand...

Motorcraft SAE
80W-90
Premium Rear
Axle Lubricant
F-550 Dana 135
Click to expand...

 
I have run Lucas 85-140 in my off road rigs for decades. Currently I have a Detroit rear, elocker up front. When I had the front axle built, that's what the builder recommended. No issues.

A buddy of mine had his ARB do that same thing and the seal was leaking compressed air into the housing, forcing gear oil out the vent tube.
 
Gear oil selection aside, are we in agreement that this gear oil puking probably isn't from me hitting the ARB compressor switch while moving at highway speed?

No leaking from the vent after the drive into work this morning.
 
So you've only had oil coming out the one time the compressor on switch got touched? You've driven it again without oil coming out, without touching the compressor on switch?

I'd take it for another spin and hit the compressor on switch again. No oil. you'll know it wasn't the compressor on the first instance. If you get oil again, there's your culprit.


On the oil selection topic. I had Jantz setup my dropouts and he said to run Severe Gear 250wt. No racing, will see street driving.
 
gt1guy said:
So you've only had oil coming out the one time the compressor on switch got touched? You've driven it again without oil coming out, without touching the compressor on switch?

I'd take it for another spin and hit the compressor on switch again. No oil. you'll know it wasn't the compressor on the first instance. If you get oil again, there's your culprit.


On the oil selection topic. I had Jantz setup my dropouts and he said to run Severe Gear 250wt. No racing, will see street driving.
Click to expand...
Good idea. I'll do that on the way home today and report back.

Also plan to pull the vent tube and check for pressure in the pumpkin with the compressor on sitting in the driveway.
 
Threw the compressor switch at 55mph just like yesterday. Left it on for longer just to make sure. No leak.

Pulled the vent line and flipped compressor switch. No pressure in pumpkin. Flipped locker switch and also no pressure in pumpkin. Again verified ARB locks axle.

Fluid is still halfway up diff cover based on the ARB dipstick.

I think at this point I can rule out the compressor switch or anything else ARB related.

I guess I am left with slightly overfilled (exactly 2 quarts which is reccomended capacity) and a really hot day pulling a trailer caused it to puke out the vent tube a little.

Not sure what else it could be?
 
Last edited:
Had the same issue.
My problem was I ignored the part in the directions where they tell you to grind a channel in the lower part of the bearing counter bore on the drivers side.
This channel will let gear oil that has flowed into the drivers side axle tube flow back into the differential since the ARB air actuator blocks oil from flowing through the carrier bearing. Not the greatest design imo.
 
chevellian said:
Had the same issue.
My problem was I ignored the part in the directions where they tell you to grind a channel in the lower part of the bearing counter bore on the drivers side.
This channel will let gear oil that has flowed into the drivers side axle tube flow back into the differential since the ARB air actuator blocks oil from flowing through the carrier bearing. Not the greatest design imo.
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Interesting... was that in the TJ Rubicon axle? I didn't do the install and the instructions say it might need the axle tube mod depending on the axle.
 
Last edited:
Yes, 2006 Rubicon.
The directions are not very clear on why this modification needs done.
 
chevellian said:
Yes, 2006 Rubicon.
The directions are not very clear on why this modification needs done.
Click to expand...
Winner winner chicken dinner. I just talked to the installer and he did not grind the channel. That's gotta be my issue. I would of never figured that out on my own.
 
Thanks everyone for helping me figure this out. Almost time for beer.
:flipoff2: You're the best.

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