I've never had an air locker before so this may be a stupid question.

I had a rear ARB air locker installed "professionally" in my truck many months ago when I re-geared. I just got the large ARB compressor installed this week. With the truck sitting on stands, everything works as it should and the compressor only runs for a few seconds. No leaks in the system.

I decided to try it out running down a straigt road and turning the locker on and off. Sometimes it seemed all right and other times the compressor was cylcling every 5 seconds on/off/on/off, etc.

I pulled into the driveway, turned the locker on and the compressor ran constantly and air was leaking out of the diff. vent. Turned it off, backed into the garage and put it on stands and everything is fine again. Is this normal?

Thanks.

No!!!!!

Hopefully you were stopped when you were trying to engage the ARB.

As OOP's mentioned it isn't normal, and it shouldn't stop leaking when up on a stand. Check the diff housing fitting and see if it is tight.

W/it up on the stands can you get the ARB to engage?

If air is coming out the diff vent, either the diff housing fittings are installed incorrectly, or your ring gear ate through the hard line.

ARB changed the diff housing fittings a few years ago from threaded to a compression style, and a lot of installers have had issues with them. If you tighten them too much you tear the O-ring, if you don't tighten up enough, you get leaks. I had the same issue w/the ARB in my '91. After talking to ARB/USA in WA, and installing new o-rings the way the tech told me to, mine has been leak free for a few years now. Fortunately the tech also sent me the old fittings so, if I have to get into it again, I will install the old style fitting.

I would return to the shop that installed the ARB, and have them remedy the situation, unless they set up the 3rd, and you installed it.

Thanks for the input. I spoke with ARB in WA today and it sounds like a bad install. Not concentric or too little pre-load.

I will see if the installer (Gears and Rears in Surrey, BC, part of the Pat's Driveline group) will do anything about it. I wasn't impressed when they did the install since they had interference issues between the new pinion and locker and I ended up contacting ARB and resolving the problem for them, but I'll give them a chance to make it right. If not, I'll be asking for shop recommendations!

Any update on the issue Pyroboy?

A couple of things could cause what you see....like someone said, the ring gear could have ate the soft copper line. That could be because of the routing of the copper or an "OOPS!" when you wiggled the 3rd into the housing and smashed the copper line. You might be able to check that without removing the 3rd...just remove the brass bulkhead intermediate coupler(the blue air line is attached to it) and you should be able to see the fat black o-ring in the hole and the copper line should be sticking out about 1/8" inch. If you see no copper line at all then the ring gear probably grabbed it and sucked it into the housing.

I can't imag

Hey Zuk.

Looks like your message is incomplete? I haven't had time to look at it lately but I don't think it's the air line since it works fine sometimes. It was all put together by a gear shop so I would expect it to be done properly, but...

I'll send you a PM. It might be simplest to pull the third and send it to you to look at, if there's no obvious problem. I'm having a hard time finding people here to work on my truck that don't give it back in a worse state then when they got it.

This line in your post tells me they do not know what they are doing when it comes to ARB's.

Sent you a pm back...when you take the 3rd out let us know what you see. ZUK

edit--- if you think it's the air line then you should eliminate that from the equation before going to the trouble of pulling the 3rd.
You said in your first post that "air was leaking out of the diff" so the obvious thing to check is the fat o-ring area where the blue line goes into the brass coupler on the 3rd.

So I finally got around to pulling the 3rd member this weekend...

Copper line is good and all the o-rings are intact. Put an air hose on the fitting and it seemed to be leaking air inside the locker, which made no sense. It looked liked the left side adjuster nut locking tab was touching the seal housing so I bent it out of the way and it did not leak again after that. Will put the 3rd back in this weekend and see how things work.

Thanks for the input!