ARB Locker Problem

[teotwaki]

After my initial install ( http://www.expeditionportal.com/forum/showthread.php?t=36900 ) of the ARB/3rd member in my 4Runner all seemed fine. Recently I was out wheeling and noticed that if I had any articulation of the rear axle that the pressurized air was somehow venting into the axle and then coming out of the axle's vent cap. The vent cap is remoted on a rubber line up to the area near my gas cap.

As shown in the install pictures, there is no way that the blue air line or brass fitting on the outside are moving when the axle articulates.





All I can guess is that somehow the screw-in fitting that holds the internal copper air line has come loose from the brass fitting screwed onto the outside of the third member housing. (found this picture on the web. Not mine)

From the outside the fitting seems tight.

I still cannot see how the air flow is affected only when the axle is articulated. I would think that it would always be venting.

Is there that much movement of the copperline if there is heavy torque on the ARB?

I am okay with disassembling the brass fitting but am afraid that if the copper line "pulls" back into the housing I'd have to pull the third member to grab the line and pull it back up into the threaded hole in the housing.

 

[Tucson T4R]

That would be a very unusual failure for an ARB locker. I would focus your inspection on the air line connections at the diff housing and even back on the compressor. Seems like a poor connection that leaks when stressed is the likely cause.

 

[Desert Dan]

Does it leak air out the vent when not fully articulated?

With the locker on can you wiggle the blue hose and cause it to leak?

 

[Tucson T4R]

Oops, I just re-read the OP. He said he verified the air was coming out the diff vent breather. :Wow1:

To me that means there has to be an internal air leak inside the diff otherwise the air would just leak into the air outside the diff housing.

I have never seen this happen but it doesn't sound like a good thing.

 

[teotwaki]

Does it leak air out the vent when not fully articulated?

With the locker on can you wiggle the blue hose and cause it to leak?

No leaking when not articulated.

See the pix in the first post for how the blue line is routed. No wiggling even possible plus I even used my spare parts to rebuild the fitting on the outside of the diff housing. Even then, how would that leak air into the diff housing? That would vent directly into the atmosphere.

 

[luv2xplor]

Just a guess here but in your 3rd and 4th photos it looks like the air line might hit the crossmember when the axle articulates. Looks like the dirt is rubbed off there. Could it bend the air line enough to cause it to leak ?

 

[cruiseroutfit]

Do you or a shop close to you have access to an ARB pressure testing setup? It would be very helpful in diagnosing what is going on in your housing. The articulation part has me confused, oil sloshing off of the seal housing? But oil isn't going to hold back 80-90 psi air?

How old is your locker? Who installed it? Round cross-section o-rings on the cylinder cap or square? Ferrule style bulkhead or o-ring or the newest barb?

 

[Desert Dan]

It sound like an internal issue
I'm not sure why articulation would make it leak though.

I have had some 90 wt gear oil blow back up to the ARB air switches when the locker was released but nothing like you described.

 

[cruiser guy]

Just a guess here but in your 3rd and 4th photos it looks like the air line might hit the crossmember when the axle articulates. Looks like the dirt is rubbed off there. Could it bend the air line enough to cause it to leak ?

This looks like a good possibility to me as well. There is definite markings on the crossmember where the hose has hit in the past.

 

[01tundra]

If the preload is not set correctly on the side carrier bearings it can allow the air collar to leak. If it only does it when articulating the suspension, it could be something to do with putting pressure on one axle (assuming this is a semi-float axle). The axle housing itself can also be flexing a little during articulation.

I would call ARB's tech support and they can usually diagnose it quickly.

There has been a lot of problems with the earlier ARB's and Toyota 8" axles (well documented online) where axle housing flex causes them to leak. I believe they changed up the design over the years and have solved that issue. I never had any problem with mine when I had the factory rear axle under my truck.

 

[teotwaki]

This looks like a good possibility to me as well. There is definite markings on the crossmember where the hose has hit in the past.

I truly appreciate the thoughts and the input but that can't really happen. That cross-member is just too far forward to ever touch the blue hose. More importantly, I took those photos the day I installed the airline so those "rub" marks on the cross-member were already there, probably from me banging my head.... :elkgrin:

The angle of the photo just makes things look as if they might have rubbed. I could take some different photos to help illustrate the layout.

 

[teotwaki]

Do you or a shop close to you have access to an ARB pressure testing setup? It would be very helpful in diagnosing what is going on in your housing. The articulation part has me confused, oil sloshing off of the seal housing? But oil isn't going to hold back 80-90 psi air?

How old is your locker? Who installed it? Round cross-section o-rings on the cylinder cap or square? Ferrule style bulkhead or o-ring or the newest barb?

A local ARB experienced shop performed a rebuild of a lightly used locker, about 10K miles on it. IIRC it was an RD-23. I gave them a call and they said that they used a newer "gooved" O-ring. They did not say "square" though.

I'm pretty sure that the bulkhead is an older style ferrule on the copper pipe.

As an update, now if I am on level ground the compressor just runs and the locker does not engage. I may be resigned to just pulling the 3rd if I cannot effectively remove the bulkhead fitting from the outside to inspect things.

I'm guessing that the copper line may have pulled out of the bulkhead fitting or it has broken somehow.

PS: placed a call to ARB and all they could offer was that I had to pull the 3rd member. I did find the PDF on bulhead fittings and I'll see if I can tell which style I have. It may well be a ferrule type on the copper tube.

Bulkhead fitting info at http://www.arb.com.au/resources/pdf/airLockers/4-01.pdf

 

[robert j. yates]

If the preload is not set correctly on the side carrier bearings it can allow the air collar to leak.

I just went through this on the rear D44 in my TJ. Gears and locker were professionally set up 5 years ago with no problems ever until I got air pissing out of the axle with consistent compressor engagement. Gear guy suspects that pulling a trailer with steep axle gears caused pattern to back off somewhat which then created a preload issue for the air collar.

 

[teotwaki]

I finally had a chance to crawl under the 4Runner tonight. I disassembled the brass bulkhead fitting. It was fairly easy and it turned out that it is the type with a rubber O-ring to seal around the copper air line. I think it is a 170105 kit.

The O-ring seemed to be a little torn, not evenly compressed and the rubber seemed a little stiff and not so compliant. I suspect that the shop that did the work did not replace it. I need to find some of these things locally but it is metric. I'm hoping that this is my only problem.

 

[cruiseroutfit]

If you can't find the o-rings give me holler, I've got baggies of them.