ARB Locker / Onboard Compressor Diff Oil Backflow Blowout (1 Viewer)

[effjay80]

ARB rear locker and onboard ARB single tank compressor in engine bay have been great. Slee installed so done right. Last week was out and re-pressured tires up as always for the run home. Got home and big pool of oil collecting under front tire - opened hood and source was at the compressor solenoid. At first thought I blew up the compressor but no oil in these and was definitely diff oil. Oozing out of the locker air line at the solenoid. Pulled both ends of the air line and blew out a line full of diff oil. All seems to be fine again after blowing out the line. This never happened before and not sure why this time. My diff breather and line is wide open. This seems to be a common issue but don't recall a MUD thread on the subject.

I'm going to add an arb purge valve. Should the solenoid on compressor be replaced after receiving a diff oil bath?

My tasting notes for 75 90 dino diff oil - earthy with sulphur overtones with a hint of burned gear. Not recommended.

 

[ChaseTruck]

Typically the culprit is this:

On our ‘93, the junction to the copper line failed.

Threads about ‘Selectable lockers’ usually have the pertinent info.

 

[leonard_nemoy]

Yep, I just had to do a full rebuild on both my arb lockers because they were leaking internally and forcing the gear oil into the compressor. On both of mine the copper didn't fail but the o-rings inside the housing failed.

But maybe you got lucky and you just have a plugged diff breather. Definitely check that first because I guess it can cause the same issue.

 

[John McVicker]

Consider doing this before you open up your diff:
A) remove your axle breather hose.
B) blow it out with compressed air
C then shoot some carb cleaner in the hose…both ends
D) more compressed air.

Not at all uncommon for this hose to get plugged up. Make sure what ever ‘filter’ you have on the end of the hose is also not plugged up. Good idea to do this from time to time. Good chance this is your problem. If not…have to open the diff.

 

[LongDuck]

As John says above, the area around my ARB compressor under the hood has been coated in diff blowby oil the whole time I've owned it. If you're not pressurizing the system regularly, the diff oil will work it's way up that line all the way to the solenoid. The net effect is that when you go to use them off-road, the pump comes on, then shuts off - and you get no locking, because the line is clogged up.

Before any trip when I think I might need the air lockers, I pull the air line at the diff, stick an old sock over the anti-kink spring, and the power up the compressor. It runs, then stops, oil shoots out, it runs, then stops, more oil shoots out, and eventually it clears the lines. You'll know when the compressor runs nonstop and there's no more oil shooting out of the line. Reattach the air line to the diff, then test the lockers.

It's a hassle, but I dare say it's a known issue.

 

[John McVicker]

Yep, good explanation @LongDuck . I hit my compressor at least once a week…when it stops running, I then hit both lockers, one at a time, listen for the locker to ‘click’, the compressor will then go on…then do the other locker until it clicks.

At least once a week.

 

[effjay80]

Thank you all for the information and using the "selectable locker" thread search I see lots more info on the subject.

My breather line is new and wide open. I removed line and valve on back axle and could easily put breathe through unobstructed. I blew the oil out of the locker line and will start doing a weekly actuation and pre-use line purge as suggested. Fingers crossed I don't need to re-build the lockers.

Thank you again!

 

[TexasJack]

Add plumber's tape to the nut that screws into the compressor and then just tighten up the nut (as far as it will go). I had backflow on mine and this fixed it.

 

[effjay80]

Thanks for the tip and will try that too.

 

[jonheld]

The pressure switch that ARB supplies with their compressor can be horribly inaccurate and can over pressurize the lockers. This leads to eventual failure of the O rings inside the lockers. On my 91 with a York OBA system, I added a second regulator for the lockers.
The current pressure switch they supply cycles from 70-100psi. I regulated mine down to 68psi after some trial and error. Lower pressure=longer life while still having reliable locking.

 

[leonard_nemoy]

If you're not pressurizing the system regularly, the diff oil will work it's way up that line all the way to the solenoid

This is not correct. There are only two reasons you would have gear oil making its way to the compressor/solenoid.

#1 the diff breathers are clogged which is an easy fix.

#2 the locker is leaking air inside the axle housing.

It is not normal for oil to be in the compressor or solenoid and it will not simply flow up the line into the compressor by itself.

 

[use2bn83]

Some good stuff up above. I’ll add a few other causes I’ve seen.

1. Folks activate the locker and drive at high speeds (like over 20mph). For some reason, this usually exacerbates a small misalignment issue and turns the seal housing into an oil pump.

2. The carrier bearing preload nut that the seal housing rides against gets buggered from a spanner wrench or has a burr on it for some reason. This “cocks” the seal housing and eventually causes premature wear on the x-rings inside the seal housing. And then you basically have an oil pump.

3. The copper line is not bent properly during install. When the diff is put back in the copper line makes contact with the axle housing and “cocks” the seal housing…. again eventually creating an oil pump.

Nearly every arb solenoid I’ve seen has at least trace amounts of diff oil on them. The bonded seal acts like a piston sliding in a cylinder and eventually some oil gets past and works it’s way up.

 

[LandLocked93]

Great reminder! ... to go with e-locks.
lol