Another Rear Air Suspension Thread.....!

[Palmo]

Hi All!

I know.....another Rear Air Suspension Thread! BUT..... I have searched and read loads of info including 'battenberg's' excellent thread 'Disco II Air Suspension - All you need to know..!' which has helped me get this far, but I am now stuck!!!!

The Story so far.....
I bought my 2000 D2 (ES v8 4.0 Auto) back in June. The previous owner told me that it had a new Air suspension Compressor approx 12 months ago. For the first month I had no problems, then one day whilst loading to return home from a weeks holiday, it sank to the ground on the O/S/R. To cut a long story short, about a week later I replaced both rear air springs. The suspension now stays level and raises and lowers as it should.

However...... during the past few weeks I have began to experience problems when my car trailer is attached (twin axle Brian James). The trailer itself causes no problems however, when I load a car on the following happens:
1. If the engine is not running and the suspension is left at 'normal' height both sides sink equally to the bottom. Attempts to raise the rear by starting the engine (with all doors shut) and pressing the raise button all fail. However, if I unload the car and start the engine, it begins to raise immediately.
2. Alternatively, if I leave the engine running and raise the suspension before beginning to load, the suspension sinks to just below 'normal' height. If I leave it to idle, it will raise back to the higher position after approx. 5 mins.
3. I have no issues driving once lowered back to 'normal' height once step 2 above has been followed.

Why does it only sink when subjected to a 'heavy' load? It didn't do this when I first got it before the rear springs needed replacing. I have taken the cover off the Compressor and it does indeed look like 'new' (it is spotless) and appears to be a genuine Land Rover part. Any suggestions? - it appears to me to be a problem at the compressor end - leak perhaps - valve block, rather than the airbags, which as stated were both replaced recently?

Any and all help greatly received as I don't want to get stranded miles away from home trying to load a car!!!!!

 

[bennybenny]

rip it off and fit springs ....simples .......ive done this and never looked back .....

 

[Palmo]

rip it off and fit springs ....simples .......ive done this and never looked back .....

Not really what I'm wanting to do as I think the D2 with Air Suspension drives a LOT better than when on springs + they are loads better for towing when they are working right. And there is the insurance aspect.....7 seats etc.....!

As mine appears to have a newish Compressor and has new air springs I'm getting there.....I think.....just need to sort this latest quirk out I hope!

 

[thought it was mine!]

plus the new mot in january, new rules, new changes what rules will be brought in on mods?

 

[Palmo]

plus the new mot in january, new rules, new changes what rules will be brought in on mods?

Completely agree with regards the MOT.....what I do know is any 'safety related items' that are fitted, must work as intended - I believe without exception. As most D2's have Air suspension, I presume this will need to work as intended, the grey area of course is whether this is a 'safety feature' in the same way as ABS, TC, SC etc. are?

With regards mods (not relating to safety items) I have not seen anything firm to suggest these will be treated any different to they are now. Interesting times ahead!

 

[sierrafery]

Keep the SLS cos it's marvelous ...especially if u want to tow things or load the rear.

So ... to get closer to the answer, next time when u want to leave the car make an effort, take off the compressor housings cover, and unplug everything there( all the 4 plugs, valves first) while engine still running..... then stop the engine and let it so. If it will stay on level this way it might be a management issue...if it drops is a valve leak (i suspect the exhaust valve which can't fully close under load. Anyway if u want to sort this out do that and report back...i will guide u further ... it's possible that u'll have SLS warning then but dont bother with it

 

[Palmo]

Keep the SLS cos it's marvelous ...especially if u want to tow things or load the rear.

So ... to get closer to the answer, next time when u want to leave the car make an effort, take off the compressor housings cover, and unplug everything there( all the 4 plugs, valves first) while engine still running..... then stop the engine and let it so. If it will stay on level this way it might be a management issue...if it drops is a valve leak (i suspect the exhaust valve which can't fully close under load. Anyway if u want to sort this out do that and report back...i will guide u further ... it's possible that u'll have SLS warning then but dont bother with it

Thank-you very much for the advise. I will indeed follow this, but I need to be clear on what you are advising.....obviously you're not saying to disconnect the airpipes themselves, I presume you mean unplug the electrical connectors.....however, aren't there 3 and not 4?
1. Power feed to compressor
2. Valve to right airbag
3. Valve to left airbag

Where and what is the 4th?

Regarding the SLS warning, this doesn't worry me as I have access to a diagnostic scanner that works very well with the Disco from past experience.

Many Thanks!

 

[Stoneytd5]

plus the new mot in january, new rules, new changes what rules will be brought in on mods?

ok so basicaly the new rules to mods in mot are as follows...if its ment to be fitted with a cat and isnt its a fail even if it passes an emissions test as to every thing else to do with modifications stays the same as its always done..... iam an mot testers personaly any one who says different is just scare mungering!!
as for you air suspension sinking early discovery 2's used to suffer with the height sensor boards playing up ( on the most common height point ) it sounds to me very much like this ie with the difference in heights with or without a car on your trailor....they also used to suddenly drop the suspension when you had gone over a speed bump to!! main dealer £27 each.

 

[sierrafery]

Off course i meant the electric plugs

The 4'th is the exhaust valve. I'll try to explain it briefly> the sensors are commanding the 2 air supply valves(or just the part that is lower) to open and the compressor to work when rising is necessary... if load removed from vehicle the sensors are opening the 2 valves(or just the valve from the part which is higher) and the exhaust valve to release air from the system. Unplugging everything while engine is running the sytem must remain "sealed" if no leaks cos nothing will let air out.... and so on... we'll get closer soon

this will help >

 

[Palmo]

Off course i meant the electric plugs

The 4'th is the exhaust valve. I'll try to explain it briefly> the sensors are commanding the 2 air supply valves(or just the part that is lower) to open and the compressor to work when rising is necessary... if load removed from vehicle the sensors are opening the 2 valves(or just the valve from the part which is higher) and the exhaust valve to release air from the system. Unplugging everything while engine is running the sytem must remain "sealed" if no leaks cos nothing will let air out.... and so on... we'll get closer soon

this will help >

Thanks for this additional information..... I will report back when I have investigated further!

 

[Palmo]

ok so basicaly the new rules to mods in mot are as follows...if its ment to be fitted with a cat and isnt its a fail even if it passes an emissions test as to every thing else to do with modifications stays the same as its always done..... iam an mot testers personaly any one who says different is just scare mungering!!
as for you air suspension sinking early discovery 2's used to suffer with the height sensor boards playing up ( on the most common height point ) it sounds to me very much like this ie with the difference in heights with or without a car on your trailor....they also used to suddenly drop the suspension when you had gone over a speed bump to!! main dealer £27 each.

Thanks for this also, I look at the ride height sensors as well and report back!

 

[sierrafery]

the test i suggested u is to figure out if the sensors or other components are doing the trick or not,...this step by step diagnose will lead u to the real fault ... u can replace them without any further thinking if u want then pray it was the good move(which is possible)... just disconnect the battery first or u'll need recalibration.

 

[Palmo]

the test i suggested u is to figure out if the sensors or other components are doing the trick or not,...this step by step diagnose will lead u to the real fault ... u can replace them without any further thinking if u want then pray it was the good move(which is possible)... just disconnect the battery first or u'll need recalibration.

Point taken!!!!!! I will follow your testing approach and report back. Thanks again!

 

[thebiglad]

In order or priority these are the main causeall items:

Air springs = 90% of problems

Ride-height sensors - 5-8% of problems

Compressor = 2-5% of problems.

Therefore it would seem logical to me that as you have a new compie and new springs it would be wise to just go ahead and replace both ride height sensors.

If you do decide to do this, please ensure that you:

1. Park on level ground:

2. Disconnect your main battery earth lead before starting work on the sensors. This will ensure that you don't need to re-calibrate them.

Good luck

 

[chosenview]

I have just had a bunch of warning lights up on the dash and the plugin has identified the valves as the problem.

I have checked microcat and it looks like the air compressor box is 1 unit. Does anyone have the part numbers for the control valves in the box?

Steve

 

[frostymorning]

Hello all.

New member here, but one who has read this forum before and used the advice to identify and repair problems with the airbags and sensors. Sorry if I'm going over old ground, but I seem to have a new problem and would appreciate some help with diagnosis.

One of the bags on my TD5 is leaking. Replacements were bought and I intended to fit them this weekend...but before I got a chance the car sank overnight and wouldn't rise as usual when the engine was turned on.

The compressor runs initially, but then cuts out and neither bag appears to inflate at all. It's now been like this for three days, despite numerous attempts at starting the engine and making sure all the doors were shut.

Where should I start looking?

 

[Soloby Rob]

rip it off and fit springs ....simples .......ive done this and never looked back .....

It's funny how the best advice is being rejected. You just can't beat KISS engineering.

 

[sierrafery]

jack it up from the towbar to 2/3 of normal height then try again... it would be good to plug in a tester and erase the fault codes cos there might be ecxeeded duty cycle codes for the compressor stored cos it overworked due to the leaky bag

 

[frostymorning]

I would if I had a towbar........ but thanks for the advice. I'll try it on axle stands.

And I've just got hold of a Nanocom Evolution. This is its first test.... so I don't really know what I'm doing yet. I connected it up and there were no faults showing for the SLS.

 

[sierrafery]

give it inflation command through nanocom....it must be under "circuit tests" menu or something cos i dunno how nanocom works