bursts of noise from suspension compressor

Hi folks,

Our 2004 Td5 Disco has started making strange noises at the air compressor. The suspension system is working fine, no leaky airbags, been there done that and the height sensors too. Immediately after the Disco has been driven and is parked, as the ignition key is turned to the off postion, a loud vibration can be heard from the compressor. It happens in roughly two second on-off bursts for up to ten seconds. It continues after the key has been removed from the switch.

Is this a known problem?

I would have thought the power would be removed from the compressor with the ignition switch removed, so could this be air leaking back through a valve? After it stops the air supension gives its usual gentle hiss as it lowers slightly when you get out.

Puzzled.

Mine does that.

Like a little " Uzi " burst under the car.

Been like it for the 3 years I,ve had it. ( not saying its right though ! ).

Del.

Mine too does this, very rare tho. I thought it was the fuel lift pump, because it happens normally when I switch the engine on and then off within a couple of seconds. My idea was it was self purging the air out of the fuel lines.

Mine does it too, its just the suspension levelling itself. Nothing to worry about.
Mark

My drive slopes. If I reverse on to it it pumps up like that. If I drive on forwards you hear the air being released instead.

Like others have said it quite normal so don't worry about it.

He did say the ignition was on the off position, so how can the compressor put air in to the bags without power?

I wondered about that with mine as the workshop manual suggests it won't run the compressor with the ignition off but it does seem to on mine just as you leave the car.

If you later put stuff in it waits till you run the engine before pumping up as it should.

I just put it down to one of those things it does.

This behaviour is perfectly normal - the sls system remains "live" for up to 20mins after the ignition is turned off.

Hi Guys,

Thanks for so many responses, I appreciate them.

We've had the Disco for six years and it has only started this loud noise from the compressor unit at ignition switch-off over the past four days. It doesn't do it every time though. We still get the hiss of air as the SLS levels the vehicle after you've parked, I think this is the noise some of you are describing? This new noise happens in short loud bursts before the usual levelling hiss starts.

I've a bit more time over the weekend, I'll see if I can get it to do it more often to see if there is a pattern to when it does it.

Thanks again.

Mine does it when you park it on slightly uneven ground, I presume it's just bursts of compressor to level the vehicle! Not heard it when parking on level flat ground.

Its not a "normal" noise unfortunately, its the sound of the compressor when it's a little "worn". It should be much quieter in opreation. I could get my old one to do at will.
it normally happens when you park the car up and switch off the engine quickly whilst the compressor is still self levelling the vehicle. If you park up and wait a few seconds (5-10) before you switch of I doubt you will ever hardly hear it. I could monitor it by watching the SLS light I have on the dash, and when the noise occured it was always on.

Urban Panzer said:

Its not a "normal" noise unfortunately, its the sound of the compressor when it's a little "worn". It should be much quieter in opreation. I could get my old one to do at will.
it normally happens when you park the car up and switch off the engine quickly whilst the compressor is still self levelling the vehicle. If you park up and wait a few seconds (5-10) before you switch of I doubt you will ever hardly hear it. I could monitor it by watching the SLS light I have on the dash, and when the noise occured it was always on.

Click to expand...

Never seen my sls light on when it does it! Compressor doesn't seem to make this noise at other times only when stopped! Doesn't make that noise when I select off road height!?!

probably did not make it clear, the SLS light Im refering to I fitted myself as a mod to the supply line of the compressor so I can monitor when its working, this is an easy way to keep an eye on its "normal" operation and when its running to much, ie if you have a leak or the compressor is failing. Mine to did not make any noise when "using" it for offroad mode, but it made the awful noise discussed here when parked up sometimes, few weeks later and it was running a hell of a lot longer after start up etc (monitoring light) then finally gave up completely.

Thanks for the ongoing chat and inputs guys.

Yesterday the Disco was used quite a lot and didn't make the noise once. We let it stand for a few seconds after coming to a halt before turning the key to off and no noise, just the self levelling hiss after we got out . Hmmm. The pump sounds really smooth when doing its normal job. I checked the air input filter to the compressor too, behind the rear n/s light cluster. It was bone-dry, not even condensation in the plastic pipe leading to the compressor, so no evidence of moisture in the compressor from there at least.

We'll see how it behaves today.

it's just the car trying to level it's self, but the compressor should be pretty much quiet in operation ,so you could have a lot of wear on it

The car can only level itself by dropping the rear end if its been loaded up, and at the point it only opens the valves to release air an lower the rear. The compressor cannot be operated with the engine of (lift the rear) so when it does make the noise, its when it was trying to level it up but the ignition was switched off before the cycle was completed.

The tale goes on! We only ocassionally get the noisy bursts of sound from the compressor after stopping the engine, often we just get the usual levelling out hissing sound. But, sometimes when we switch the engine off and pull the key out the compressor makes bursts of much more noise than usual but they stop as soon as the driver's door is opened and start again for a few seconds after it is closed and the door locked with the remote. We've not worked out a way of making it do this, it just does it sometimes, so it's hard to do any tests. I need a lamp across the compressor to prove it is really that that is running, it sounds like it but is it?

I know the levelling system is suspended if a door is opened but what is happening suggests the compressor can still be operated with the engine off and key out. So why is the compressor pretty quiet the rest of the time and doing its job well but noisy and running in short staccato bursts after the engine is shut down? It's only been this way for a few weeks. Surely if the compressor were getting worn out we'd have the noise all of the time?

Hmmm What opens the air outlet valves? Could this noise be part of the valve mechansim trying to operate but failing and making the noise? If the SLS system tries in bursts to down-level that might be what I hear and then when it works we get the hiss as usual and all is OK.

hello i have a rangr rover l322 05 plate and the pressure swith that works the air suspension needs replaceing can some please tell me how to locate it thanks jim