Another Air Bag / Height Sensor Issue

Hi all

I have an issue, I've spent considerable time on here searching for the definitive answer and can't quite get it right.

Ok, I sold my 300 and bought a TD5 ES a couple of months ago, and it has been excellent until recently. Its started to sit down overnight on the offside. It lifts back up on start up, and usually is ok through the day, although it did appear to be dropping whilst driving at least once. I lifted it up today with the dash button and went under armed with a squirty of soapy water and the air bag appears to be ok. In fact both look as though they have been replaced fairly recently. I then noticed that the offisde bump stop was AWOL, and then saw that the height sensor on this side had split at its lower mounting and on the whole looked pretty weak.

Now, could this be the real reason that the car is squatting overnight? Or should I also be looking elsewhere? If this is my problem, will disconnecting the battery before fitting a new sensor remove the need for re-calibration?

I would be grateful for any help and information that anyone could provide please, thanks.

Hi, sounds similar to problems I've had. I would check the valve block next to the compressor for leaks. One of my valves is leaking through the electrical contacts, I'm just waiting for a replacment to arrive which I HOPE will fix the problem.
I also noticed that one of the ride height sensor has some damage (split at attachment point) but this should only affect the tilt of the car

good luck

Chris

Disconnecting the battery before unplugging the height sensors is very wise indeed, unless you want the car dropped on you ;-)

You may or may not need to recalibrate after fitting new height sensors - depends whether the new ones are sufficiently close in values to the old. I've certainly got away with it.

David

Hi Rosedale,
I also had a similar problem, it was the airbag.
Nothing showed on the "Fairy Liquid" test - it was really intermittent!
It was less than 3 yrs old, so I thought it can't be the airbag.
I stand corrected it can be the airbag!
Mine died on me 50 miles from home - limped home @ 20 mph with limited suspension, hitting the bump stop regularly.
When I got home the bump stop was no longer there.
Maybe I was lucky, I think I was, but get it sorted soon or your air-suspension compressor will die!
Mine was only 2 weeks from symptoms till collapse.
New airbag sorted it.
I've owned my D2 for 8 yrs
Best of luck

airhook

The soapy water trick is "unreliable" for the air springs themselves unless the leak is NOT under where the bag rolls over itself.

Treat the airbags AND height sensors as "serivce items" and replace them every couple of years.

If the height sensor is broken, ie split end, then yes that could cause the issue, but it would be unlikely to cause the back to sit right down, it would more likely produce an uneven affect with the rear suspension.

Hi Rosedale,
just to reinforce what I said earlier regarding the valve body. I replaced both air bags (£150) only to find that it isnt them!! so as it only takes 5mins to check the valve body, I would recommend doing it before buying new bags (although as others have said its best to treat them as replacable items).

Good look

Chris

Hi all, thanks for your advice. I'm going to have a look at the valve block as Chris suggests, is there a particularly good method for checking it?

Firstly start car and let suspension rise, then turn car off.
probably worth disconnecting the negative battery lead, as the slabs unit still has power when ignition is turned off.

If the whole black box can just be unbolted from underneath the passengers side door, then do that. My bolts were seized, but its still quite easy.
Take the lid off the box, use a 7mm socket/spanner to undo the 2 bolts on bottom left side of box - this holds the valve block in place. use a 10mm spanner to disconnect the pipe from compressor to valve block (compressor end of pipe), you can now lift the valve block up and out of the 'black box', detach both electrical connections.

Your suspension will still be up as the valve block 'should' seal the system. Use soapy water or 'leak detector' and spray all around the valve body including in both sets of electrical connections (this is mine was leaking from). I also checked that the central pipe (to compressor) wasnt leaking (mine was).

only takes 5 or 10 mins to do this

Hi Chris, thanks for that. I've just had a quick look at the car and realised that I think it is sitting down on both sides. The reason being that I have a missing bump stop on the offside, so this is settling further than the nearside which obviously rests on its remaining bump stop. I am thinking that in this case it is definitely losing air somewhere other than the bags which points as you say to the valve block. The joys of a Disco 2! I am replacing the bump stop tomorrow, and so will get it up in the air and have a look in this direction.

Well, much investigation has finally revealed...............nowt. The valve block appears ok as do the pipes. I've replaced the offside bump stop and the car no longer drops to the axle, obviously, but it remains up on the nearside dropping only 20/30 mm on switch off. Think I'm going to replace the offside bag and have done with it. Oh, and I've now got a leak from the transfer box, just enough to brass me off.

Rosedale said:

dropping only 20/30 mm on switch off..

Click to expand...

(at least)this is normal behaviour