Air Suspension - slow air leak

[coolum]

I have a problem with the car lowering over a period of time in the garage - it is also showing a dash light warning of suspension fault on longer drives - the compressor can be heard to run at odd times.
I have had the front suspension balance (left right) control valve replaced for the suspension. There were no other apparent leaks under workshop tests.


But this has not rectified the problem, So I removed the fuse over the last couple of days and the result has been a slow lowering of all bags at approximately the same rate @ 35mm lower in 24 hours (within 5 mm).


My question is:
What is the most likely culprit in this situation ?


My Guess (logically) is a slow leak in the Main Air Compressor tank fittings - it would be unlikely to be the holding tank itself, but I would suspect that there is a hole in a line or a seal that is allowing a drop in the pressure in the main tank?


Am I on the right track?


Your thoughts please?


Many Thanks


Steve

[Graeme]

All corner valves are closed unless the height is being adjusted.

I suspect that you did not remove the 20A suspension system fuse in the engine bay fuse box because removing that fuse will result in just the leaking corner being lowered overnight.

A corner can lower due to a leaking air-spring, a split air-line tube between the air-spring and the valve block (unlikely as the air would probably escape quickly) or the particular valve in the valve block is leaking. Most likely cause is a leaking air-spring, for which setting to off-road height then spraying with soapy water often identifies the leak.

[coolum]

I removed the yellow 20 amp self levelling fuse from the box near the battery.
I thought this was the correct one! do you have other advice?


As Mentioned this info was sourced on this forum (- many thanks )... and the car has dropped in all four corners the same (approximate height of 35 mm.


The car is not doing any self levelling at this time ...


To check I have opened doors at various times and this usually results in a 'fart' or two .. which is no longer happening


Is it possible that overall pressure is being lost to cause all to drop simultaneously.


I will double check the fuse tomorrow but I have cross checked the fuse prior to removal as being the one that effects this operation .. I got normal height and closed the doors to allow for self levelling to occur - then moved the car took out the fuse and then waited for self levelling after removal of the fuse and nothing has evident.


Any more clues please? one thing that has occurred to me is that the last thing prior to this 'issue' commencing was the installation (by British offroad) of the Blue GOE height adjusting rods? I did not think anything could go wrong ... perhaps I should return these to stock while this is being investigated?


Thanks


Steve

[Graeme]

The 20A fuse should be #26. Its needed to operate the valves etc so if removed then no corner or other valves can be opened. With this fuse removed there should be a suspension fault when the ignition is switched on and attempting to lower to access height (or raise if the engine is running) will have no effect.

The 35mm height change is of no real significance other than if all are the same then the system is lowering all corners trying to level.

There is no overall pressure. When the compressor stops and the corner valves are all closed the compressor exhaust valve is then opened until the pressure in the lines is down to 1 bar.

A height sensor giving faulty readings can also cause the vehicle to be lowered but not while the 20A fuse is removed.

The GOE rods should have no effect even if not all fitted using the same set of holes as the suspension ecu would think that the ground isn't quite level. However if the vehicle is now left overnight higher than previously then perhaps a leak has been exposed due to the air-spring folds now using different sections of the sides of the air-springs.

[letherm]

Any more clues please? one thing that has occurred to me is that the last thing prior to this 'issue' commencing was the installation (by British offroad) of the Blue GOE height adjusting rods? I did not think anything could go wrong ... perhaps I should return these to stock while this is being investigated?


Thanks


Steve

Hi Steve.

I'm no expert but I attended Gordon's seminar in Sydney recently and he explained how the rods work. they simply push the sensor higher or lower than normal because they create a different length to the standard rod. Maybe one is not set the same as the others ???? Other than that they really shouldn't have an effect on the air suspension as such as they just fool a sensor into thinking it's at a different height.

Martin

[coolum]

It seems I did a wrong count on the Fuse ..


Again thanks Graeme and the others who have commented.


I am hoping to see one side dropped to the ground tomorrow to identify the culprit once and for all. Then off to the repairer to do the magic.


I was not thinking the GOE rods were the cause but I usually try to return to basics to find issues.


All should be revealed overnight.


Steve

[shining]

I have had 2 leaks in my air system. Both in the piping around the compressor, just from vibration friction where the pipes were rubbing together. As they were just pin holes I repaired both in and installed spacers to prevent recurrence.
My symptoms were "suspension raising slowly" or something similar and access height only.

[coolum]

The Divers side Front went from 800 to 775 = approx. 25 mm +/-
The Passenger front went from 805 down to 790 = approx. 15mm +/-


I have had a new balance valve block installed, could it be both airbags or a slow leak remains in the Valve block balance controller?


Any further thoughts please?

[Graeme]

The left side going down less than the right will be due to the left side having taken on some of the weight from the right having dropped due to leaking. Get it up to off-road height then spray around the fold with soapy spray looking for air bubbles.

Both front and rear cross-link valves are closed by default, only opened at slow speed combined with significant articulation.

[coolum]

Thanks Graeme


Steve