air springs (sls)

i have searched and read all the threads on this subject but i still am unsure of my problem, i have a 2000 td5 discovery , i have checked and double checked the springs for leaks, but if i park on a slope (NOSE UP) the bags deflate right down to the stops in about 1 min.i have checked the height sensors and they seem to be ok. if i park on the flat or down hill there is no problem, any ideas please.
UPDATE..today i drove my car over some very bumpy terrain i noticed after this that the springs had deflated whilst driving (something to do with the road maybe?)

also if i do park on a hill and before i get out, if i inflate the springs with the yellow height button a little bit then return the height to normal i can leave the car and the back dose not drop.
i hope this extra info will help someone solve my problem.

It could be the spring-seated vavles that hold the air in the bags - located between the compressor and the bags. Mine went down over a period of 1 week once (car didn't move all week) but haven't done it since - thought bags at fisrt but then after a bit of deduction put it down to the vavles not seating properly as a one-off. Biggest (and most expensive) worry for all bag-related leakages is that the compressor isn't running permanently as a result, until it goes pop. You can hear the compressor running from outside the car (it's behind the passenger sill, halfway down the car) and you can check if it's shutting itself off once the bags are full.

ould be interesting to park the car in the position it's in when it leaks, and see if the compressor is 'topping up' regularly.

should the compressor be running permantly then? ( whlist the car is running) ithougt it just topped the bags up as needed?

keithark said:

should the compressor be running permantly then? ( whlist the car is running) ithougt it just topped the bags up as needed?

Click to expand...

No! if it's running all the time it will eventualy burn out

Jason2 said:

No! if it's running all the time it will eventualy burn out

Click to expand...

Sorry! That's right - that was my point, but I didn't explain it very well..

You need to check that the compressor isn't topping up regularly.

Forgot to add, the other thing that made me realise that it was probably the valves having a one-off leak on mine is that both sides dropped slowly, not just one corner... a leaky airbag will often just drop one corner.

If you look at the schematics on the RAVE cd-rom you can see how the system works. The valves are all within the black compressor box behind the passenger sill.

Just to reiterate - the important thing (for your wallet) at this stage is to ensure that the compressor isn't running all the time, or very regularly. It will soon burn out if it is.

I'd love to have an LED on the dash to show when the compressor is running. Anyone done this? Do you think it would be hard? Maybe a relay running of the power supply to the compressor??

how could i check if it is the valves leaking? but the thing that puzzles me is it goes to the stops in a minute flat when parked uneven or up hill, is there an electrical connection to these valves, because i have noticed i dont get the discharge of air when i stop the car and get out anymore( sls) i think?

udate please read first post

look underneath the car, under the passenger seat and you'll find what looks like a battery box, there are two turnbuckle screws that will open the cover with a 5p piece. at the front end of the box you will see three narrow pipes going into the valve block. a little soapy water on them may identify if the valves are leaking? you can get to it without jacking the car.

if the bags (and the pipe joints on the bags) arn't leaking, then they are the next link in the chain, bar pipes themselves leaking.

thanks for all your replies i hope i can now solve this problem my car is lhd so i take it this box is under the drivers seat? by the way is this a different box to the one that houses the compressor or the same one. sorry but im not with the car at the moment.

keithark said:

thanks for all your replies i hope i can now solve this problem my car is lhd so i take it this box is under the drivers seat? by the way is this a different box to the one that houses the compressor or the same one. sorry but im not with the car at the moment.

Click to expand...

It's the same box that houses the compressor. Black box, 'bout the size of a shoe box? I would imagine that's it's still on the nearside/RHD Passenger side, even though yours is a LHD

keithark said:

but the thing that puzzles me is it goes to the stops in a minute flat when parked uneven or up hill

Click to expand...

Obviously you need to try and catch the source of the leak during this time! Have the soapy liquid ready! Or to be fair, if it's coming out that fast, you should be able to hear it?

Hi Keith One of my problems I had was every now and then (it could be every two to three weeks) the back end would sit down this was due to suspension air bags. Possible problem is leaks where you cannot see them and they don't always leak it just depends at what angle the car is sitting. Land rover recommend these bags are replaced every 5 years as the rubber starts to crack and you cannot see it unless you remove them like I did then put some air into them (use tyre pump) while immersing them in large bucket of water you should look for bubbles if you see them or any cracking where the rubber is attached to the ends replace them. last thing you want is the suspension to give way totally like mine did I was lucky I was not going fast but it could have gone on open road with caravan in tow. I dread to think what could have happened. Regards PS if changing them buy 2 new ones (check out ebay) and get some new top mounting clips the old ones will probably be corroded and you will only need 4.

mrfix it, if the bags were leaking would the car go down on bothsides equally? how fast they deflate sometimes leads me to think it has to be a valve problem, or maybe both ,the car is 7 years old with only 70,oookm, but i do live in a hot dusty climate! out with the soapy water again this weekened i think! thank yoiu all for your help,
keith

keithark said:

mrfix it, if the bags were leaking would the car go down on bothsides equally? how fast they deflate sometimes leads me to think it has to be a valve problem, or maybe both ,the car is 7 years old with only 70,oookm, but i do live in a hot dusty climate! out with the soapy water again this weekened i think! thank yoiu all for your help,
keith

Click to expand...

Hi again Keith My car would sometimes go down in about 10 minutes the bags have seperate air control valve to allow them to inflate to differant extents so if one bag leaks it will not nessaseraly let the other down as well. there is compleat air compressor on ebay with all the valves see item 170135538617. My car is 1999 therefor about same age have a word with Island 4x4 01795 580332 and ask them how many air bags they sell. I find it is usually a good indication of componants failer. I go by the idea if they have not sold many it is the last part I would look at. also as Land rover recomend they are replaced at 5 years it is because they have experanced this problem on the Range Rover which has had this type of system for much longer than the Discovery. I would not have found the leak using soapy watter with the units still fitted to the car as the leaks was next to the steel rings that attach the rubber to the base and top plastic mounts. Regards

the deflation of the bags is controlled by a third solenoid controlled valve attached to the acutal compressor.

during normal driving, the compressor will kick in and supply air to the valve block, if it recieves a signal to do so from either ride height sensor.

the valve block will direct the air to one or both of the bags depending on the signal it recieves from the one or both ride height sensors

the computer will allow for a certain amount of movememnt in the ride height sensors before kicking in the compressor. it will also talk to the body control computer ecu to make sure that all the doors are closed (as a saftey measure) before making any adjustments to the compressor or suspension. the compressor only works when needed.

the only places that could leak are:
the bags
the pipes supplying the bags from the valve block
the control valve block
the exhaust valve block.
any of the connections in this chain.

pipes themselves are unlikely to leak, the connections at each end might.
the bags you have tested....
the valve block and the exhaust valve are now possible candidates.

a leak in one side will not cause the other to leak unless you have a control malfunction from the computer or the valves are sticking/leaking.

it is an easy 1/2hr job to remove the compressor unit with valve blocks and inspect and test it. however, you will need the chassis supported on stands so the car dosent drop onto its axle. with a 12v supply you can test all the operation of the valve soleniods and compressor, leaks can be ironed out on reassembly.

Battenburg, thank you for that very detailed reply, that made things much clearer for me.
keith