Member Since: 24 Nov 2017
Location: Pontypool
Posts: 193
Air Suspension Issue/Question
So just before Christmas my air suspension which I knew needed attention gave up. I knew the rear air bags weren't the best and was getting an error (can't remember what it was now) but the upshot was I bought the a compressor overhaul kit, 2 new rear air suspension units and a valve seal kit for the valve block by the complressor.
Thes I fitted and everything is good apart from the compressor is a very active. Always comes on if left parked up for a few hours and sometines during a jjourney as well.
So today I had some time for a closer look and find out what is going on
The rebuild kit I ordered had the replacement Aluminium end cover and it is the push fitting which is leaking.
I also slackened off the pipe that goes from the resevoir valve block to the compressor drier and this pipe was under pressure without the compressor running.
Is this correct? Should the delivery pipe between the compressor and valve block be under pressure all the time even when the compressor isn't running?
While I was under there I also checked all of the fittings back to the rear air bags with leak detector spray and it appears this this is the only leak
20th Jan 2019 12:54 am
indy4x
Member Since: 24 Nov 2017
Location: Pontypool
Posts: 193
Anyone?
From memory, when I did the compressor and valve block overhaul at Christmas the air line between the valve block and dryer in the computer was pressurised, but I wouldn't stake my life on it
22nd Jan 2019 1:20 am
indy4x
Member Since: 24 Nov 2017
Location: Pontypool
Posts: 193
I did do a few searches on this site and elsewhere but failed to find a definitive answer, there was a thread what I found on this forum and have borrows this picture but as the OP was having issues in not sure it is correct
22nd Jan 2019 1:25 am
indy4x
Member Since: 24 Nov 2017
Location: Pontypool
Posts: 193
In the picture above, union 9 between the valve block and compressor is pressurised when the compressor is idle on my D3.
The OP has it the same so I am assuming it is correct
Either way I have a replacement pipe and push fit connector for the air dryer end cap so will fit and see where this takes me
22nd Jan 2019 1:30 am
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4619
indy4x wrote:
Anyone?
From memory, when I did the compressor and valve block overhaul at Christmas the air line between the valve block and dryer in the computer was pressurised, but I wouldn't stake my life on it
There should iirc be residual pressure from the dryer to the valve block. If you found a leak elsewhere and sorted it you should be fine now. This would explain the constant running of the compressor. What type of compressor is fitted, Hitachi or AMK?yµ (idµ - eAµ) ψ=mψ
22nd Jan 2019 1:47 am
indy4x
Member Since: 24 Nov 2017
Location: Pontypool
Posts: 193
Compressor is Hitachi
I only checked the work I did for leaks, didn't go further but porbably need to.
Its just noticable that after standing for a few hours the compressor will kick in when I start it
23rd Jan 2019 7:04 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4619
If it does it everytime you have a leak!yµ (idµ - eAµ) ψ=mψ
23rd Jan 2019 7:11 pm
indy4x
Member Since: 24 Nov 2017
Location: Pontypool
Posts: 193
I do but what I'm trying to ascertain is does the pipe from union 9 to the compressor stay pressurised when the compressor switches off. I appreciate the will be some residual pressure but does the EAS valve block stop pressure from the air tank bleeding back into the compressor?
If the valve is supposed to stop air going back from the tank to compressor then mine ain't doing it
One other question, with the IID tool, if monitoring the gallery pressure is this the pressure in the air tank?
25th Jan 2019 1:27 am
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4619
If you go into "live values on the IID you can observe the solenoid and exh valves operation. It will be displayed as either 0% or 100% open/closed. Air from the reservoir does not flow back into the compressor. The solenoid controls the flow of air to and from the reservoir, it must be either 100% open or 100% closed depending on the cycle of the compressor. (ie running - not running!)
The Gallery is a shared space within the reservoir valve block which ensures all valve blocks are subject to the same pressure. A pressure sensor monitors the "system" pressure alongside temperature sensors on the compressor and the motor.
Watch your live values! You should see the operation of the solenoid. Its easy to remove it and clean if necessary. Should you suspect any leaks externally, spray the area with soapy water, but from what you have said I suspect you might just be able to hear a leak.yµ (idµ - eAµ) ψ=mψ
25th Jan 2019 2:26 pm
indy4x
Member Since: 24 Nov 2017
Location: Pontypool
Posts: 193
Thanks for the comprehensive reply so yes I do have a problem with the compressor valve block letting air back to the compressor.
Valve block has been apart and new o rings fitted and gave it the once over to make sure it was clean of any chuff from the air dryer
Will monitor live values today but am tempted just to splash out on a new valve block as potentially I could once again take it to bits and not solve the problem
Let's see what the live values show 1st though
25th Jan 2019 2:39 pm
XDAndy
Member Since: 16 Jan 2018
Location: Gibraltar
Posts: 597
indy4x wrote:
Its just noticable that after standing for a few hours the compressor will kick in when I start it
PROFSR G wrote:
If it does it everytime you have a leak!
Just curious here. My disco always has the compressor kicking in on engine start, but suspensi9n goes up and down ok and doesn’t seem to drop on being left standing. I’d put this down to normal behaviour.
Are you saying the fact that the compressor runs on every engine start is a sign I need to investigate for leaks?
Kind regards
Andy
25th Jan 2019 3:23 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4619
If you drop the suspension and raise it back to it normal height the compressor will kick in to replenish the reservoir. So at that point before you switch the engine off the reservoir should be full, yes?
If you come back to the car after a few hours and start it, if the compressor kicks in again I would hold you have a leak. For comparison, I have just started my own a while ago after being parked for over 24hrs. The compressor did not kick in. Sometimes of course it does, but that depends on the conditions/ cycle when I last switched off!
Bring up live values, look at the solenoid whilst manipulating the suspension between the normal and lowered height settings. You should see the operation of the solenoid open/close. If it operates as described its possibly not the issue. That said, if you remove the feed pipe from the compressor to the reservoir, does the reservoir release its contents completely? If it does this seems wrong to me.yµ (idµ - eAµ) ψ=mψ
25th Jan 2019 3:52 pm
XDAndy
Member Since: 16 Jan 2018
Location: Gibraltar
Posts: 597
Yikes. Better get leak hunting then!
25th Jan 2019 4:13 pm
indy4x
Member Since: 24 Nov 2017
Location: Pontypool
Posts: 193
New valve block arrived today, late home from work so not time to fit, hopefully tomorrow night
30th Jan 2019 12:48 am
garrycol
Member Since: 06 Dec 2010
Location: Canberra
Posts: 1115
XDAndy wrote:
Yikes. Better get leak hunting then!
It is all normal for the compressor to kick on on start - depending on pressure in the tank it will run for a long or short time. If tank is basically toppped up it will only run for a short time. My car does not drop and the compressor always runs a bit on start.
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