Ok, if its going down overnight then you HAVE a leak somewhere,which doesn't mean that your pump isn't also knackered.
Have you thoroughly leak checked visually and with soapy water, car needs to be jacked up to check airsprings extended.
Waste of time asking for advice until you've done this as everything is guesswork.
IMO I would think you have had a leak for sometime and the pump has been running more often to cope with the airloss and is now unable to cope either because it's knackered or the leak is now to large

Tervueren said:

IMO I would think you have had a leak for sometime and the pump has been running more often to cope with the airloss and is now unable to cope either because it's knackered or the leak is now to large

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I was thinking this but he hasn't said he has had any problems before with it going down overnight. I reckon there just isnt enough air in the tank due to the worn compressor which failed to properly bring the car up giving the impression of a kneeling corner.

Replace the compressor seal and go from there, once thats done you can see how long the compressor runs for once the tank is pressurised and then see if you have any dropping overnight.

-Wills

Wills you may be right, but from his first post when i parked it i left it on normal height and this morning it is low on the drivers side front only which to me is a leak and as far as I can see he hasn't checked the airbags extended which is where all the nasties lurk

Paul you stated in a previous post you had used an independent compressor to test part of the system?

Do you still have access to the compressor, remove the pipe from the vehicles compressor and connect it to the independent compressor some how, if so vehicles suspension system should rise (if thers no air leaks or burst bags).

There maybe another way to check the vehicle compressor, you stated that the OSF airbag collapsed first if you remove the pipe from the airbag and kink it to stop the air escaping do the other airbags start to lift the vehicle if the OSF height sensor is moved manually, if so theres a good chance the system has just lowered its-self to the bump stops because of an air leak in the OSF airbag.

Hi ZZR, yes i still have the comp but when i tried that the air just blew out of the exhaust valve on the valve block. I will try your second option over the weekend and see what happens. failing that i see no option but to recon the pump and see what happens. thanks for your help.

Paul A said:

Hi ZZR, yes i still have the comp but when i tried that the air just blew out of the exhaust valve on the valve block.

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The compressed air should enter the valve block and be directed to either the airbags or the air reservoir tank , it should not be vented to atmosphere, if the air is coming out of the exhaust valve filter you may have an open/stuck valve.

You have tried connecting your independent compressor to the valve block which seems to rule out a compressor fault (at the moment), but if the compressor has run for a very long time the piston seal may have been damaged by over heating.




I would personally now proceed as follows:

1. Using the independent compressor, remove each airbag supply pipe one by one (possibly from the main valve block) if the airbag lifts, move on to the next one. If you have access to 4 axle stands support the vehicle while doing so, this will make checking the overall system condition easier, if all corners have been raised/supported and airbag condition checked, move on to the valve block.

WARNING NOTE. By using the above method there is no limit to the height/pressure available, so an airbag could burst/collapse with dangerous results.

2. Disconnect all electrical connections to the control coils on the suspension manifold block, supply air from the independent compressor to the air inlet port, if the air is escaping from the exhaust port, I'd be looking for a leaking/stuck valve spool (the reason for disconnecting the coils is the system self check/adjusts the vehicles height every few hours even with the ignition switched off).

If no air leak reconnect the valve coils and turn on the ignition, if the leak returns you have an electrical control problem.

3. You should now have isolated the main problem, why the suspension will not raise and hopefully carried out the repairs. Now refit the vehicles air compressor if the system doesn't lift you may need a compressor rebuild....

HI ZZR thanks for helping, i will try all these out over the weekend (if it stops bloody raining) I did notice that when i reconected the pump after trying the independant comp it didn't blow out of the exhaust valve, it only did this with the independant comp! Paul

Paul A said:

HI ZZR thanks for helping, i will try all these out over the weekend (if it stops bloody raining) I did notice that when i reconected the pump after trying the independant comp it didn't blow out of the exhaust valve, it only did this with the independant comp! Paul

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I'd have a look at the diagram/manual for the manifold valve block and see if theres a pressure relief valve set at a lower pressure than the compressors supplying?

Sorry to sound stupid but how would i do that, i have the cd rom manual but would it mention pressure values.

Paul in the front suspension section page 7 (system operation), there is a schematic diagram of the manifold block (inside the dotted line) and the rest of the suspension system outside the line.

There doesn't seem to be pressure relief valve listed, only a control pressure switch item 5. Although just above NRV3 to the right there is a valve that could be an over pressure safety valve (possibly marked as (5) ), but also on the other side of the diagram there is another item marked 5 which could also be the pressure switch.

There is a possibility that the passage ways inside the valve block have been drilled in such a way that 5 and (5) both meet at the same point on the valve block and they just feed a pressure switch, that is the wonders of schematics!!!

Just follow the schematic, but be warned a schematic is an outline of how the system works, not a definitive layout/location of parts in/of the system.


PS.The vehicles pressure switch cuts the system pressure at 150psi approx, how much pressure does other compressor produce?

Paul the schematic shows valve 13 in the open to atmosphere position, I suspect this is its normal position and is moved to the closed position after the compressor has started to run and produce pressure.

PS. Try connecting the independent compressor and then operating the suspension control system with all the doors closed and see what happens.