Identifying ARB air locker o-ring issue (1 Viewer)

[dividedwood]

Looking for a little guidance here.

I bought an FJ80 a few months ago with front and rear ARB air lockers. They worked when I bought the truck, but I noticed after I drove it home (1,500 miles) that they only worked intermittently. I replaced the o-rings in the compressor since air was definitely leaking from there and thought that would be the end of it.

Now, it holds pressure at the compressor, but when I cycle on the rear locker, it runs indefinitely and I can hear air leaking near the rear diff area. (The front works as it should now that I fixed the compressor.) I couldn't feel any air coming out of any of the fittings (not commensurate with the amount of noise it was making). There's a connector splice about 10" off the diff. I disconnected it at the compressor end and covered it with my thumb and the compressor turned off, suggesting that the trouble is downstream--either at the fitting on the diff itself, or inside the diff. I stopped messing with it last night because it was cold and dark.

Anyways, I'm looking for some help with regards to identifying whether this may be the infamous locker o-ring issue. I suppose if I unscrew the diff fitting and am able to cover it with my thumb to turn off the compressor, it has to be somewhere in the locker, right? If so, are there any concerns about backlash or other gear setup if I need to just pull the carrier and swap the o-rings?

I've pulled a carrier on a semi-float a few times before (to put Aussie lockers in Jeeps), so I'm not too concerned about that, just want to make sure there isn't something else I'm missing here.

 

[ferg]

If you have ARBs you should be able to pull just the line from the fitting by pressing down on the outer collar of the fitting, then check the line with the thumb plug plan. Sometimes the line get stuck after being in the fitting for a long while. Just wiggle it around a bit and it will eventually come free.

 

[dividedwood]

If you have ARBs you should be able to pull just the line from the fitting by pressing down on the outer collar of the fitting, then check the line with the thumb plug plan. Sometimes the line get stuck after being in the fitting for a long while. Just wiggle it around a bit and it will eventually come free.

So, I did that at the splice fitting--or one end of it at least. That's how I tested it and figured out the leak was somewhere past that. Are you saying I can do the same thing at the brass fitting on the diff itself?

 

[ferg]

Depends on the fitting. Some are like the splice fitting, some are actual compression fittings. If compression type, just unscrew the cap and remove the tubing. It should come out with the bead crimped to the tube.

 

[I Lean]

Once you take out your third member, the ARB parts are pretty easily accessible--no worries about gear setup changes, you won't touch any of that. (unless your problem ends up being internal to the ARB, which is rare)

If you hear air leaking inside the diff, it's most likely going to be either the bulkhead fitting, or the copper line is broken/torn, or the O-rings. Also, you should be able to check pretty easily if the leaking air is coming out the axle breather.

 

[dividedwood]

Once you take out your third member, the ARB parts are pretty easily accessible--no worries about gear setup changes, you won't touch any of that. (unless your problem ends up being internal to the ARB, which is rare)

If you hear air leaking inside the diff, it's most likely going to be either the bulkhead fitting, or the copper line is broken/torn, or the O-rings. Also, you should be able to check pretty easily if the leaking air is coming out the axle breather.

Good to hear. I'll take a closer look and probably order up the parts. Air coming out of the axle breather would indicate that it is a problem in the diff (i.e. one of the likely problem areas you mentioned), correct?

 

[I Lean]

Good to hear. I'll take a closer look and probably order up the parts. Air coming out of the axle breather would indicate that it is a problem in the diff (i.e. one of the likely problem areas you mentioned), correct?

Exactly. Basically, you're just trying to identify whether the leak is inside or outside the housing. If it's anything inside, then you need to pull the third member to continue your search.

With the third member out, you can put pressure to it again and it should be pretty easy to find where your leak is.

 

[dividedwood]

Exactly. Basically, you're just trying to identify whether the leak is inside or outside the housing. If it's anything inside, then you need to pull the third member to continue your search.

With the third member out, you can put pressure to it again and it should be pretty easy to find where your leak is.

Easy enough. Given a chilly forecast over the weekend, I'm not sure I'll tear into it until after Christmas, but this gives me a clear path forward. I'm sure this will be one of those times I wished I had a full-float rear... Either way, thanks for the help.

 

[mudgudgeon]

Be careful man handling the third in and out. The copper tube is vulnerable to damage, particularly putting the third back.
There's been many cases of the tube being pinched, or slightly bent on install and contacting the crown gear and eventually rubbing through.

 

[dividedwood]

Be careful man handling the third in and out. The copper tube is vulnerable to damage, particularly putting the third back.
There's been many cases of the tube being pinched, or slightly bent on install and contacting the crown gear and eventually rubbing through.

Good advice, thanks. I was thinking I might just get the whole rebuild kit ($70 or so) so I have a replacement copper tube and seal housing. This is my DD so I want to make sure I have all the parts I might need before I rip into it.

 

[beachboyy]

Pop the fill plug in your diff and accuate the locker. You’ll hear it right away (and feel it) if it’s leaking internally. I had a copper line get eaten and then later on i actually had the internals leak and had to take the ring gear back off (much bigger project).

I do have an ARB question though and I’ll try and keep it thread oriented so I don’t hijack this, but my front locker will puke gear oil back up the air line to the compressor. It does it on and off and the locker works fine. Any ideas?

 

[tacosupreme]

Pop the fill plug in your diff and accuate the locker. You’ll hear it right away (and feel it) if it’s leaking internally. I had a copper line get eaten and then later on i actually had the internals leak and had to take the ring gear back off (much bigger project).

I do have an ARB question though and I’ll try and keep it thread oriented so I don’t hijack this, but my front locker will puke gear oil back up the air line to the compressor. It does it on and off and the locker works fine. Any ideas?

Mine puke oil as well. I think it's the O-rings letting gear oil seep in when the lines aren't pressurized. I hear the new O-rings are more of an X-ring design and do a better job of sealing when the lines are not pressurized. This may be the source of the OP's leak as well.

Part 15

 

[baldilocks]

@beachboyy @dividedwood , oil traveling up the line is usually related to the tiny Oring at the bulkhead fitting.

Be sure your leak is not the bulkhead fitting before removing the third member. Good catch on the compressor Orings. Bulkhead fitting kits that include the Oring can be purchased.

Eve since ARB update the internal seal housings, they are quite reliable and trouble free.

 

[tacosupreme]

@beachboyy @dividedwood , oil traveling up the line is usually related to the tiny Oring at the bulkhead fitting.

Be sure your leak is not the bulkhead fitting before removing the third member. Good catch on the compressor Orings. Bulkhead fitting kits that include the Oring can be purchased.

Eve since ARB update the internal seal housings, they are quite reliable and trouble free.

How? (not arguing, genuinely curious)

 

[dividedwood]

@baldilocks, what would be the best way to confirm it is or isn't the bulkhead fitting?

 

[beachboyy]

Mine puke oil as well. I think it's the O-rings letting gear oil seep in when the lines aren't pressurized. I hear the new O-rings are more of an X-ring design and do a better job of sealing when the lines are not pressurized. This may be the source of the OP's leak as well.

Part 15

Funny think is I replaced that o-ring in the rear when it leaked. Then it still leaked so I replaced that whole putter ring (that has the copper line attached to it). It still leaked and that’s when I went to the internals. So i do have an extra outer ring and o-ring

@beachboyy @dividedwood , oil traveling up the line is usually related to the tiny Oring at the bulkhead fitting.

Be sure your leak is not the bulkhead fitting before removing the third member. Good catch on the compressor Orings. Bulkhead fitting kits that include the Oring can be purchased.

Eve since ARB update the internal seal housings, they are quite reliable and trouble free.

I am also curious how this can let gear oil up the line.

 

[Nors]

Funny think is I replaced that o-ring in the rear when it leaked. Then it still leaked so I replaced that whole putter ring (that has the copper line attached to it). It still leaked and that’s when I went to the internals. So i do have an extra outer ring and o-ring


I am also curious how this can let gear oil up the line.

I have this problem too
Opened up the diff and no visible problems
Replaced O ring and enlarged breather hole
ARB quality control is losing its high ratings
Concerned it could be internal to the ARB parts
To be continued

 

[baldilocks]

How? (not arguing, genuinely curious)

If the Oring is defective or missing oil will be sucked up the air line when the locker is disengaged. The air rushing back up he line will cause a vacuum.

I unnecessarily replaced both of my seal housings chasing down the reason for oil up in the air line and the compressor cycling on and off while engaged.

The oil issue was fixed when I replaced the bulkhead fitting and replacing Orings in the compressor fixed the cycling problem.

 

[baldilocks]

@baldilocks, what would be the best way to confirm it is or isn't the bulkhead fitting?

You will have to pull the air line out and inspect the Oring and general condition of the lines (plastic outside, copper inside). The bulkhead fitting kit is very affordable. Maybe you could find just the Oring somewhere. It’s worth a try before pulling the third.

 

[RhinoJr]

The seal housing o-rings aren't always the source of the leak. I've had one where the bonded seal internal to the housing failed. That's the part that pushes the clutch gear and if it leaks it can't build pressure to overcome the spring force. I'm not sure which ARB model is depicted above, but the bonded seal would be #3 on that diagram. You have to separate the case to replace it. Usually less than $30 part. Just something else to keep in mind. Good luck.