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Armyair

New Member
Hi,
After replacing my height sensors recently in a spate of tlc I noticed my rear suspension was deflating overnight on both sides. This had occasionally happened previously.
Having also noticed my new compressor running for long periods I used my faultmate to read a pressure switch open fault.
I decided to pump the suspension to max and then disconnect my battery to disable the self levelling on the suspension for further diagnostic and again both rear airbags deflate.
My current feeling is the o-rings in the valve block probably require replacing as I believe (correct me if I'm wrong) each side at the rear has its own air supply and the common connection is the valve block.
I intend to replace the pressure switch at the same time but I'm wondering if I'm barking up the wrong tree to start with.
Any thoughts / advice is welcome. Also does anybody know the procedure for resetting ride heights using vehicle explorer on a fault mate would be as once this fault is nailed will require doing.
Thanks again for any help!
 
The pressure switch open fault maybe that the compressor is constantly running to keep up with a leak, see what you get when you find and seal the leaks. That fault could disappear. Check the pipe work and connections to the valve block and the bags and the bags themselves with soapy water.
 
Cheers Wammers
I was thinking along the same lines as you with the switch open due to a leak and the compressor running to rebuild pressure but what are your thoughts about both rear shocks loosing air as I thought they were independent of each other once their feeds leave the valve block. Hence it was unlikely both failed together and the common component was the seals in the valve blocks.
Does that theory sound reasonable?
 
Armyair said:
Cheers Wammers
I was thinking along the same lines as you with the switch open due to a leak and the compressor running to rebuild pressure but what are your thoughts about both rear shocks loosing air as I thought they were independent of each other once their feeds leave the valve block. Hence it was unlikely both failed together and the common component was the seals in the valve blocks.
Does that theory sound reasonable?
Click to expand...

You mean bags not shocks. Think you have a leak, check as said. Then you will know what you have. Compressor could be running and being controlled by thermo switch and never reaching a pressure to close the pressure switch. So you may lose that fault. But whatever you have find it quickly or you will be knackering the compressor big style.
 
Thanks, The vehicle isn't a daily runner as its a weekend renovation project for the better half. We both have other reliable vehicles for daily use as I wouldn't like to rely on it until I've finished my restoration of it. Next in line is a full engine rebuild so its going nowhere in a hurry lol. Ironically living in Warks I have a number of friends who are project engineers at Gaydon LR. They all claim to be working on the new Disco's and forever claim the next gen is leaps and bounds better than the last;
They also never manage to explain why my Jag is more reliable when they are constantly boasting their designs are better than their sister companies. Lol
 
If you have a leak in one airbag, unless it's a very serious leak, the EAS will try to keep it level and deflate others.
If the airbags are more than 7/8 years old they will almost certainly be leaking.
Also worth checking for exhaust blows that might have melted an airline. Not likely to be the valve block IMO.
 
Cheers Datatek.
The rear air springs were both inflated. Then I immediately disconnected the battery as I thought this might take the EAS self levelling out of the equation. I left the vehicle in a garage for a week and on my return both rears were equally deflated.
I'm just brainstorming but thought that as the rear air springs have different air lines from the valve block and are fairly new it pointed at the common part as in the valve block.
By disconnecting the battery before leaving it I thought the EAS could not operate.
Both front air springs were still inflated. I will inspect the rear air lines again however up to now have not seen an obvious leak.
Does this alter your opinion any?
 
Last edited:
You really do need to do a soap test on it. Otherwise you are guessing, work through it step by step.
 
Armyair said:
Cheers Datatek.
The rear air springs were both inflated. Then I immediately disconnected the battery as I thought this might take the EAS self levelling out of the equation. I left the vehicle in a garage for a week and on my return both rears were equally deflated.
I'm just brainstorming but thought that as the rear air springs have different air lines from the valve block and are fairly new it pointed at the common part as in the valve block.
By disconnecting the battery before leaving it I thought the EAS could not operate.
Both front air springs were still inflated. I will inspect the rear air lines again however up to now have not seen an obvious leak.
Does this alter your opinion any?
Click to expand...
Dissing the battery is not a good way of disabling the EAS, pull the relay under the passenger seat (RHD) or leave the tailgate open.
I would still say airbags 1st, air lines second, a pin hole in the airlines is all that's needed. There are 2 separate valves for the rear airbags plus the exhaust valve which make the valve block unlikely.
Wammers is the expert on the valve block internals, he'll shoot me down if that is not correct:)
 
Datatek said:
Dissing the battery is not a good way of disabling the EAS, pull the relay under the passenger seat (RHD) or leave the tailgate open.
I would still say airbags 1st, air lines second, a pin hole in the airlines is all that's needed. There are 2 separate valves for the rear airbags plus the exhaust valve which make the valve block unlikely.
Wammers is the expert on the valve block internals, he'll shoot me down if that is not correct:)
Click to expand...

Agreed Keith. Less likely to be solenoid valves, as both rears have to leak as well as exhaust to let air out. Not impossible if they are contaminated by drier break up. But you would ask why fronts, that would just be as contaminated are not leaking, when there is slightly more pressure in them in an unloaded car to support the weight of the engine. First off as said previously, would be to check bags, lines to them and lines in general back to valve block and connections to valve block. If all that is proven sound then the valve block would come into play.
 
Thought I'd update you with the results of this air leak. After a month or so of leak checking and being unable to locate it at the rear I decided to bite the bullet and take it to an independent.
After two days I got a phone call back saying that he couldn't find any leak on the rear as both rear air springs were new and having jacked the body away from the chassis to inspect the rear air lines still nothing then as a last ditch he sprayed the valve block itself.
After 15mins bingo finally a bubble appeared from between the rear offside air valve and block.
Finally after months I have a fully working air suspension again as I replaced the valve block with a new one sourced myself as he said with over 15years experience on P38s he had never seen a seal kit work for any length of time.
On disassembly and inspection of the old valve block it appears worn under the valve itself as if the leaking air has worn a grove or the valve operation itself has pitted it.
I thought I'd post the solution to this long standing problem for any who may be stumped with similar symptoms.
 
Armyair said:
Thought I'd update you with the results of this air leak. After a month or so of leak checking and being unable to locate it at the rear I decided to bite the bullet and take it to an independent.
After two days I got a phone call back saying that he couldn't find any leak on the rear as both rear air springs were new and having jacked the body away from the chassis to inspect the rear air lines still nothing then as a last ditch he sprayed the valve block itself.
After 15mins bingo finally a bubble appeared from between the rear offside air valve and block.
Finally after months I have a fully working air suspension again as I replaced the valve block with a new one sourced myself as he said with over 15years experience on P38s he had never seen a seal kit work for any length of time.
On disassembly and inspection of the old valve block it appears worn under the valve itself as if the leaking air has worn a grove or the valve operation itself has pitted it.
I thought I'd post the solution to this long standing problem for any who may be stumped with similar symptoms.
Click to expand...

As long as the block itself is undamaged, fitting new "O" rings brings it back to "New" spec. No reason if the "O" rings are good quality why the life should be any shorter. I've done a few with no problems.
You should look at changing the air dryer. If there was corrosion present that would suggest humidity in the system, also check the air tank has no water in it.
 
Mmm.
No leaks but still an unserviceable EAS. The bags are new, the valve block is new (the old still leaks from under the valve even after a new o-ring has been installed). The fault now shows as a random rear bag lowering then inflation on listening excessive valve switching followed by compressor running and finally culminated in a hard EAS fault my better half explaining why she had removed the faultmate from the glovebox to the kitchen table and a recovery truck rid home!
The Fault code was pressure switch open and I suspect the thermal cutout stopped the compressor and the bump stops beckoned.
Once home the fault was cleared the EAS recharged and the vehicle left overnight to see what happened.
First the front right dropped then later seemed to have inflated and both rears dropped.
So I pumped the EAS again disabled the EAS ECU left it for two days and not a mm dropped.
My thoughts are now the Valve block is being told to randomly operate and so I think I may have a faulty EAS ECU as I've seen a recall for a similar fault on cars of my year from LR or a faulty valve driver! As the suspension is now 48hrs and it still hasn't dropped! any ideas or does my theory hold. There is definately no air spring or line leaks. Checked, Double checked and triple checked as has the independent!
 
As above , Definitely sounds like a driver pack problem on the valve block, they overheat and eventually short out and work incorrectly
 
Thanks. Glad I'm not barking up the wrong tree. Best I tighten my belt and buy a new driver pack. I'm not going to fit a 12yr old 2nd hand unit just to get the same fault again down the line. Hopefully his will leave me to get on and lift the heads off and sort the gaskets.
No rest for the wicked with a P38 on the drive.
I think this has been payback for ribbing my mate on his new motor!
 
Armyair said:
Thanks. Glad I'm not barking up the wrong tree. Best I tighten my belt and buy a new driver pack. I'm not going to fit a 12yr old 2nd hand unit just to get the same fault again down the line. Hopefully his will leave me to get on and lift the heads off and sort the gaskets.
No rest for the wicked with a P38 on the drive.
I think this has been payback for ribbing my mate on his new motor!
Click to expand...
Before you fork out for a new driver pack, check the connectors in the EAS box for corrosion and also the earth point.
It may also be a duff pressure switch as it logged that error.
 
datatek said:
before you fork out for a new driver pack, check the connectors in the eas box for corrosion and also the earth point.
It may also be a duff pressure switch as it logged that error.
Click to expand...

+1. Seeing as how driver pack has nothing to do with pressure switch think that is good advice. :)
 
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