Servicing ARB air compressor for lockers

[MalcomM Senior Member Find all posts View Profile Close MalcomM]

Yup, that looks like the one.

That pic gives me a good idea of whats inside and doesn't look like there'd be an oil bath.
Looks like I can pop the end off and see what dribbles out.

[Guest Close Guest]

Yes, it says "Teflon impregnated carbon piston rings for trouble free oilless operation".

[MalcomM Senior Member Find all posts View Profile Close MalcomM]

so I wonder where the oil came from. 3 teaspoons is quite a bit. Wonder if ARB put a bit in to keep the O ring supple.
I'll have to do a taste test and see if its diff oil.

[MrX Member Find all posts View Profile Close MrX]

My guess is diff oil that made its way up the air tube? I seem to remember a thread a while ago where this was happening.

[MalcomM Senior Member Find all posts View Profile Close MalcomM]

My guess is diff oil that made its way up the air tube? I seem to remember a thread a while ago where this was happening.

Yeah, agreed. As I said above -

"The air tank has about 3 tea spoons of oil in it which I assumed came from the compressor but I guess it could have come back from one of the lockers over a period of time.
Comp is under the drivers seat so it wouldn't be a huge effort for the oil to overcome gravity and flow to the tank but I can't see how it would overcome the air lock that the valves should provide. Also no obvious evidence of oil in the lines when I had them off."

I'll have to try and determine what type of oil it is but an internet search shows that backflow seems to be a common occurrence with ARB lockers. Seems a bit silly to have to fit a catch can so I guess I'll live with it.

[Guest Close Guest]

Having destroyed a number of ARB compressors I can quantify there is No oil in them.

Oil in your tank would be coming up from the diff lockers.

[ARB 4X4 Accessories Corporate Member Find all posts View Profile Close ARB 4X4 Accessories]

Hi guys, got the PM and will respond to Malcom once I've had a chat to our Air Locker/compressor engineers.

Cheers, Sam.

[ARB 4X4 Accessories Corporate Member Find all posts View Profile Close ARB 4X4 Accessories]

Hi guys, just to clear a few things up, none of our compressors use oil so the fluid in the tank has not been transferred from the compressor itself. Likewise, there is no physical way for oil to enter the air tank, even if there is a bit of oil in the air line, in which case it would be expelled through the exhaust.


We've had a chat to our engineers and they’ve suggested that unless the oil was incorrectly introduced during installation, it may actually be water. Over time, the process of compressing air can cause water to build up in the tank through condensation. While usually very minimal, on an older compressor, it could explain the fluid that WomblingFree has found. If it’s been sitting there for a while, it’ll eventually go off, causing it to discolour and potentially look like oil.


Malcom, you simply need to disconnect the air tank, tip the water out and re-fit the tank.


Cheers, Sam.

[MalcomM Senior Member Find all posts View Profile Close MalcomM]

Hi guys, just to clear a few things up, none of our compressors use oil so the fluid in the tank has not been transferred from the compressor itself. Likewise, there is no physical way for oil to enter the air tank, even if there is a bit of oil in the air line, in which case it would be expelled through the exhaust.


We've had a chat to our engineers and they’ve suggested that unless the oil was incorrectly introduced during installation, it may actually be water. Over time, the process of compressing air can cause water to build up in the tank through condensation. While usually very minimal, on an older compressor, it could explain the fluid that WomblingFree has found. If it’s been sitting there for a while, it’ll eventually go off, causing it to discolour and potentially look like oil.


Malcom, you simply need to disconnect the air tank, tip the water out and re-fit the tank.


Cheers, Sam.

Thanks Sam

Actually I can tell the difference between oil and water. Its oil. Water would also likely introduce rust in the tank.
Although your engineers say oil cannot get back to the tank, a Google search on "arb locker oil blowback" says otherwise and that this problem seems to be quite common with ARB lockers worldwide.

Anyway, thanks for the help

Cheers
Malcom

[ARB 4X4 Accessories Corporate Member Find all posts View Profile Close ARB 4X4 Accessories]

Thanks Sam

Actually I can tell the difference between oil and water. Its oil. Water would also likely introduce rust in the tank.
Although your engineers say oil cannot get back to the tank, a Google search on "arb locker oil blowback" says otherwise and that this problem seems to be quite common with ARB lockers worldwide.

Anyway, thanks for the help

Cheers
Malcom

Hi Malcom, certainly didn't mean to suggest that you didn't know the difference, only to relay that our engineers thought this was the only logical explanation.

The reason for this is that if the compressor is used even semi-regularly then there will always be water present in the tank, unless the vehicle is only used within a very extreme arid climate. The military actually uses portable air compressors to generate drinking water in desert operations so it's not a rare occurrence.

The pumping (or blowback) phenomenon is something that only occurs while the diff is unlocked (depressurised) and there is no path across the solenoid into the compressor when the diff is unlocked. It is related to the migration of a hydrodynamic film across the seals, generally due to incorrect setup of the diff during installation. However, this can't occur while the seals are pressurised. Reports of oil travelling back to the compressor are only ever related to signs of oil at the exhaust port of the solenoid, never inside the tank.

The only other explanation is that oil has been inadvertently added to the tank during installation or servicing. Our Air Locker engineers have never seen even a drop of oil inside an air tank before, let alone the volume that you've mentioned.

Re rust forming in the tank, as they're actually aluminium, this isn't a possibility.

Hopes this helps explain things a little further and apologies if you took offence to my original comment.

I’d be happy to have one of our stores take a look at the compressor and the Air Locker setup to dig a little deeper if you’d like.

Cheers, Sam.

[MalcomM Senior Member Find all posts View Profile Close MalcomM]

Hi Sam

No offence taken mate.
I'm happy that ARB is saying there is nothing wrong. I've no idea how the oil got in there but as the truck is 2nd hand, anything could have happened.

Thanks for the offer of taking a look but I wont bother as the system is working ok. My original concern was simply that the comp might run out of oil and seize. That can't happen so no issue.

I really appreciate your help on this Sam as there is little knowledge out there for these comps.

cheers
Malcom