Air Suspension

[Andrew67]

G'day

Well finally limped from Barkly Homestead to Barrows Creek then onto Alice Springs.

Firstly I cleaned all three valve blocks and had the suspension start to operate correctly, moved up and down the the height modes. Bingo I thought, then after a test drive the Suspension fault came back. Then in the morning the front had lowered which was unusual because I had not had any leaks in the system previously.

What I have at the moment is the compressor starting up and stopping abruptly. Fault appears and can neither raise or lower

I disconnected the power lead to the compressor and added 12v power direct from a spare battery and it just seems to make what I can only describe as a jamming noise ? as if its pushing against an already pressurized system ? I removed the compressor and it operates fine when connected up to my spare battery.

Before I put the compressor back in the car does anyone have an idea of what could cause the symptoms ?? I have tested the relay although on reflection I should have just replaced it. Also the fuses are all ok.

Thanks in advance for any advice. Andrew

[Graeme]

FYI, the system vents the line from the compressor to the valve blocks directly after stopping the compressor so that the compressor can start next time with little back pressure.

What was the original misbehaviour of the system?

[Andrew67]

FYI, the system vents the line from the compressor to the valve blocks directly after stopping the compressor so that the compressor can start next time with little back pressure.

What was the original misbehaviour of the system?

System was fine, went to leave Barkly homestead and Suspension fault amber and wouldnt lift or lower tried driving then the red fault at 40km.

Came back and tinkered with fuses etc, cleaned solenoid valve and got some operation, disconnected battery overnight to reset. in the morning i got normal height so removed 20a fuse and then limped to Alice Springs..

Cleaning all the valves at Alice got me fully operational, till the morning when it was low at the front.

[Graeme]

That's typical behaviour of the compressor failing to get the reservoir up to pressure triggering the amber warning light then later the compressor unable to get to or maintain the selected height mode (usually normal height) on all corners so the light goes red and the suspension drops to the bump-stops. Stopping then restarting the engine restarts the timers which gives time to get the suspension up as much as possible to allow the 20A fuse to be removed to prevent lowering to the bump-stops. If the compressor has overheated then allow time for it to cool before restarting the engine.

The compressor could be weak but you stated that the compressor has recently been changed so unlikely but possible.
The dryer could be blocked but the compressor has recently been changed so very unlikely.
The compressor exhaust valve could be leaking although not a common fault.
An air-spring could be leaking. Removing the 20A fuse overnight will reveal a leaking air-spring.
A valve block could be leaking at a fitting, either because the fitting isn't tight or the valve block has split.
A valve block could be leaking from under the back plate due to a failed o-ring. I've suspended a valve block in a container of water with the airlines still connected to find the culprit. However the leak was quite slow so only caused lowering overnight, never a warning light.
An air-line could be damaged but such damage usually results in a major loss of pressure such that it is not possible to raise the vehicle much at all.

Knowing the fault codes may help in diagnosing the cause. Spraying soapy water around the base of air-springs can confirm a leak but cannot rule-out a leak.

[Andrew67]

That's typical behaviour of the compressor failing to get the reservoir up to pressure triggering the amber warning light then later the compressor unable to get to or maintain the selected height mode (usually normal height) on all corners so the light goes red and the suspension drops to the bump-stops. Stopping then restarting the engine restarts the timers which gives time to get the suspension up as much as possible to allow the 20A fuse to be removed to prevent lowering to the bump-stops. If the compressor has overheated then allow time for it to cool before restarting the engine.

The compressor could be weak but you stated that the compressor has recently been changed so unlikely but possible.
The dryer could be blocked but the compressor has recently been changed so very unlikely.
The compressor exhaust valve could be leaking although not a common fault.
An air-spring could be leaking. Removing the 20A fuse overnight will reveal a leaking air-spring.
A valve block could be leaking at a fitting, either because the fitting isn't tight or the valve block has split.
A valve block could be leaking from under the back plate due to a failed o-ring. I've suspended a valve block in a container of water with the airlines still connected to find the culprit. However the leak was quite slow so only caused lowering overnight, never a warning light.
An air-line could be damaged but such damage usually results in a major loss of pressure such that it is not possible to raise the vehicle much at all.

Knowing the fault codes may help in diagnosing the cause. Spraying soapy water around the base of air-springs can confirm a leak but cannot rule-out a leak.

Hi Graeme thank you for the response. It does sound like the compressor as you suggest. I did fit a replacement but only a cheap one (China) $350 It seemed to work ok Fitted it Camooweal and certainly improved the ride. Got the Barkly and next morning the Amber light. I wasn’t expecting to get the same years as an original but just. Week 😂😂😂😂 wished I had reconditioned the old one. Maybe time for a AMK upgrade ??

[loanrangie]

Hi Graeme thank you for the response. It does sound like the compressor as you suggest. I did fit a replacement but only a cheap one (China) $350 It seemed to work ok Fitted it Camooweal and certainly improved the ride. Got the Barkly and next morning the Amber light. I wasn’t expecting to get the same years as an original but just. Week 😂😂😂😂 wished I had reconditioned the old one. Maybe time for a AMK upgrade ??

It does sound like your cheap compressor is failing or has failed , if you still have the original hitachi rebuild it with a kit,i wouldn't fit an AMK.

[Andrew67]

It does sound like your cheap compressor is failing or has failed , if you still have the original hitachi rebuild it with a kit,i wouldn't fit an AMK.

Yes I still have the original Hitachi compressor, my only observation was that the lines to the pump and Solenoid Valve block from the dryer appear to be riveted ? the cheap one I have has threaded connection to the compressor body and riveted on the dryer cap to the valve. I considered using the dryer and rings to rejuvenate from the new one onto the old one. Or as you suggest rebuild the old one.

Have you tried removing these seemingly riveted lines ? or am I mistaken and they can be removed ?

[Graeme]

They have collars that need to be pressed and held to release the plastic pipes. The collars may be filled with dirt which can often be washed out with a good jet of water.

[Tombie]

It does sound like your cheap compressor is failing or has failed , if you still have the original hitachi rebuild it with a kit,i wouldn't fit an AMK.

My Hitachi was questionable when the vehicle was 6 months old so as a precaution dealer upgraded to AMK for me.
Its now 11 years old and faultless..

[Andrew67]

They have collars that need to be pressed and held to release the plastic pipes. The collars may be filled with dirt which can often be washed out with a good jet of water.

Thank you Graeme,

Will have a go at rebuilding the original with the dryer, dessicant and seals from the new one

Andrew