ARB Copper line pushing out of compression fitting

nc_jk_crawler

Member
Joined
Apr 4, 2017
Location
Greenville
I have ARB lockers front and rear. Both axles are having this same issue. I have the old style connection with the blue line. It is connected properly but after a few cycles, the copper line blows out of the compression fitting and air comes out of the vent tube. Any ideas what is causing it to not stay? I had to order a new seal housing because the front one got chewed up by the ring gear.
7ae9c6360aaf9817ff605615e7528e4e.jpg
81e2114d7a9dc9fb2b7936208c95f663.jpg
 
The line is not properly secured in the bulkhead by the compression fitting. Not being simplistic, but that's really all it can be.
 
You can convert to the new type fitting.

ARB Air Locker Bulkhead Fitting kit - New Style How To


As a side note, I'm not really sure why ARB isn't using a Swagelok fitting for that copper line. The answer is probably that it costs too much (even in a brass fitting instead of $$$ stainless), or maybe they don't have an off-the-shelf fitting for a plastic tubing to copper tubing union in a bulkhead flavor. But, if you really want it to not fail, Swagelok is usually the solution.
 
Last edited:
If I remember. Copper line through fitting tapped into housing.
Compression ring or ball shape, copper through that with nut capping and applying pressure.

First, is the base fitting for the ball shape or slightly tapered torpedo type.

Second, does the copper just slip over or does it fit concentric enough to provide some sliding resistance.

Third, does the nut bottom out easily. It should start easily enough but Definately provide some resistance to seating before very snug.

Fourth, don't be afraid to tighten fairly well, given using a line wrench.

Fith, make sure your line seats and goes through the ball end before tightening.

Done right that line should get snatched clean apart if caught or most likely rip the fitting out of the cast.

My bet is on. One of three.

Not tight enough on the wrench.
Not enough tube through the compression fitting to seat each end.
Or some fitting mismatch, like metric tube slipping in a standard fitting.
 
WARRIORWELDING said:
If I remember. Copper line through fitting tapped into housing.
Compression ring or ball shape, copper through that with nut capping and applying pressure.

First, is the base fitting for the ball shape or slightly tapered torpedo type.

Second, does the copper just slip over or does it fit concentric enough to provide some sliding resistance.

Third, does the nut bottom out easily. It should start easily enough but Definately provide some resistance to seating before very snug.

Fourth, don't be afraid to tighten fairly well, given using a line wrench.

Fith, make sure your line seats and goes through the ball end before tightening.

Done right that line should get snatched clean apart if caught or most likely rip the fitting out of the cast.

My bet is on. One of three.

Not tight enough on the wrench.
Not enough tube through the compression fitting to seat each end.
Or some fitting mismatch, like metric tube slipping in a standard fitting.
Click to expand...

Thanks for the response. I think the copper line just isn’t far enough in the compression fitting. I’ll make sure to hold pressure on it inside the diff while I tighten it up


Sent from my iPhone using Tapatalk
 
Fabrik8 said:
You can convert to the new type fitting.

ARB Air Locker Bulkhead Fitting kit - New Style How To


As a side note, I'm not really sure why ARB isn't using a Swagelok fitting for that copper line. The answer is probably that it costs too much (even in a brass fitting instead of $$$ stainless), or maybe they don't have an off-the-shelf fitting for a plastic tubing to copper tubing union in a bulkhead flavor. But, if you really want it to not fail, Swagelok is usually the solution.
Click to expand...

I’ve debated it. It’s such a simple issue that I feel I’m doing something wrong and it’s not necessarily broken. Lots of people have the old style and swear by it


Sent from my iPhone using Tapatalk
 
That is a good point though; where are you getting the copper tubing from if this has happened multiple times? Any guarantee that it's the proper size or wall thickness?
 
Fabrik8 said:
That is a good point though; where are you getting the copper tubing from if this has happened multiple times? Any guarantee that it's the proper size or wall thickness?
Click to expand...

They are ARB seal housings so they are the correct 3.5mm. I ordered a new one to replace the front obviously so I’ll be able to compare the new to the rear to test for any differences
 
So tearing the rear apart today and the connection is good with the copper line. There’s a leak internally. Pulled the carrier and tons of dirt and sand is coming out of the ring gear bolts and everything else. Any tips from where to go from here? Taking the arb apart now
f52f0dc03c3369ed78f5a7d4443621d1.jpg
db17ec24b3fd13e5f6b7015d98f27c1b.jpg
a1daef0a6fdcb7223426f46b32e1e439.jpg
5cb63decd712753edd0a97b85439c5d6.jpg
 
So I’m helping him get it tore down. Before we pulled the carrier it we checked the bulkhead and it was still snug in there. Sounded like it was leaking air towards the center of the carrier, not around the seal housing.

After getting the case split it appears to have dirt and metal shavings around the bonded seal. Is there anyway way that could cause it not to seal?

@Jody Treadway
 
Last edited:
How would the dirt have gotten in it? Vent hose off and go through a water hole? If the dirt/shavings were in close proximity to a seal, I'm sure it could cause it to leak, especially if the seal got nicked.
 
a_kelley said:
How would the dirt have gotten in it? Vent hose off and go through a water hole? If the dirt/shavings were in close proximity to a seal, I'm sure it could cause it to leak, especially if the seal got nicked.
Click to expand...

Oh he sunk it about 6 months ago. Water ruined the bearings both front and rear.
 
I'd say any sealing surface got scuffed up and damaged by that discovery.
Yuk, yuk, and more yuk.

Every bearing and seal would be replaced by the looks of it.

Id say the internals of the air locker may be damaged. Mating surfaces and the bonded seal. Really depends on the time and coarseness of material.

The bonded seal acts like a baloon or creates the chamber needed for air pressure to properly force the clutch into the fine teeth on the housing.
 
Waiting on him to clean out the threads on the housing for the cover and I’ll help him get the carrier back in and verify everything is working again. I’m bending some tube for the front of the k5 maybe doing a little bit of a brush guard deal.

His fiancé is so mad lol
 
330f77a87c5828901083cad83fd5de08.jpg


Got it back in, everything seems to be working for now. Hopefully it stays this way. Doing his front locker next weekend. Maybe the neighborhood kids will show up again saying we are building monster trucks.
 
iwaxmyjimmy said:
So I’m helping him get it tore down. Before we pulled the carrier it we checked the bulkhead and it was still snug in there. Sounded like it was leaking air towards the center of the carrier, not around the seal housing.

After getting the case split it appears to have dirt and metal shavings around the bonded seal. Is there anyway way that could cause it not to seal?

@Jody Treadway
Click to expand...

Sorry, been out if town with no interwebz.
Y'all did what I would have done. Clean it well, replace all the seals, reassemble cleanly
Nice work guys!
 
Well that lasted a week, stuck a borescope in the fill plug and verified the copper tube is still intact. But got that awesome air leaking out the axle vent. I really would hate to pull the cover again just to try something else. And looking at the pictures taken last weekend, you can see some wear worn into case housing.

24dd068f367760db02c37aa184df6ba8.jpg


Here is a zoomed in picture. I was assuming that slight difference and how you have to use slight force to get the seal housing o rings to go around it would be fine. Probably an big oversight on my part. But very curious to others thoughts on this.
 
If its not smooth you could eat up seals. Also when you tore it apart did you replace the bonded seal? My brand new out of the box ARB had a bad bonded seal. Had to pull it all apart and replace it. Been good ever since.
 
87TPIYJ said:
If its not smooth you could eat up seals. Also when you tore it apart did you replace the bonded seal? My brand new out of the box ARB had a bad bonded seal. Had to pull it all apart and replace it. Been good ever since.
Click to expand...

Haven’t pulled it back apart since. The bonded seal and o rings were all replaced. It worked for a day and leaked afterward
 
Back
Top