Hi All,
I could do with some advice please from a D3 suspension guru.
compressor and tank were changed about four years ago.
I recently got the yellow warning after about 3 miles into most journeys.
Stop turn off and restart it would run for hours without problems.
Fault was air pressure rising too slowly.
when I checked it compressor temperature was over 100 deg.
I changed the compressor, but think I have an air leak because it seems to run too often.
if I watch the suspension data when I switch off all valves are closed but the gallery pressure drops rapidly to 99 at about 10 units a second.
Also if I run the compressor to fill the tank it runs and stops normally after 20 seconds or so.
If I wait a couple of minutes and run it again it tops up again, even though all valves are closed.
Is this behaviour normal, sounds like a leak to me.
I have checked compressor and valve block in the compressor housing with soap and water, the new compressor did leak, but now leak free.
Any pointers to common leaks which would cause this please, and is the gallery and tank pressure behaviour normal.
Regards
Bob
22nd Aug 2020 1:48 pm
Breg90
Member Since: 04 Feb 2017
Location: Falkirk
Posts: 348
You WILL kill your compressor again if you keep driving without fixing the leak.
Joints in the system are:
Entry to each bag on the top of the suspension tower
At the valve blocks (behind front bumper on driver side for the front, center valve block - between reservoir and compressor, rear valve block - on the side of PSR suspension tower.
Joints at the compressor/tank
You might have air bag leaks, reservoir leaks, or a chaffed through air line.
I've never done this, but there is a fuse for the air system that stops it self correcting when parked up. You measure the vehicle height at each corner, pull fuse, leave over night. Find out which corner has dropped. That will help focus the search.
Also get the suspension codes read and see what that tells you.
The longer you leave this the more expensive the solution will get.
Hope that helps,
AdrianSeries one 1949 - in bits, chassis is strapped to the ceiling in my garage (beside the canoe)
LR 90 - In bits
Disco 3 - currently in bits
Thanks Breg90,
I am not shure if the valve block by the compressor should shut the front and rear it feeds.
The pressure drop I described is there when all the valves indicate closed on the diagnostics.
I need to look the centre valve block function up to se how far the air gets when its parked up.
Thanks for your help.
Regards
Bob
22nd Aug 2020 2:56 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4658
What fault codes are you getting?yµ (idµ - eAµ) ψ=mψ
Hi Prof SRG,
Pressure rising too slowly is the error as described above.
I have been reading up and now believe I have an air leak between the reservoir blocl and the front or rear valve block.
I was asking if there are any known leak points on this pipe route.
I have just bought some quick connectors and stop valves to isolate the leak.
Regards
Bob
22nd Aug 2020 6:36 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4658
It's not just leaks that will throw that type of code. Basically anything that restricts air flow as well as leaks. Do you have the actual code? What type of compressor, and is it genuine or aftermarket?yµ (idµ - eAµ) ψ=mψ
22nd Aug 2020 6:43 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 4658
Deleted post duplication yµ (idµ - eAµ) ψ=mψ
22nd Aug 2020 6:44 pm
TT___50
Member Since: 07 May 2017
Location: God’s own Country
Posts: 171
As above would help to get the codes read.
Also try pulling fuse F26(?) and measure the height of each wheel. Recheck in the morning to see where it’s dropped.
Hi Both,
Thanks for the further advice.
The problem is described in detail in the first post, I apologise for its length.
The error is " C1A20 pressure increases too slowly"
I have checked the height following morning and there is no significant drop, at most a couple of mm.
The new compressor is a new original Hitachi.
It did leak on both tubes in the drier end cap, I changed it for an aluminium one and now there are no leaks on the compressor or reservoir valve block.
What I would like confirming is that the gallery pressure should not drop to zero when the engine is switched off.
I have read the description of the suspension operation and can't find any reference to it venting.
The reservoir pressure drops slowly, as described above.
I have some 6mm fittings coming to isolate the front valve rear valve and tank to investigate further.
Thanks for the continued input, if someone could confirm that the gallery pressure should not drop that would be very helpful
This is a duplicate of post in compressor failure thread appears dead, Admin please delete as appropriate.
EDIT
IMPORTANT The correct thread for the Voss fittings in the valve blocks is 1/8 BSP 9.7mm 28 TPI M10 x1
will fit.
Push fit fittings are available from the usual suppliers in this size.
After asking on the forum for info about the gallery pressure for an occasional pressure rising too slowly fault, I did not get much input.
So I decided to write up my findings and cure.
There is a lot of reluctance to approach the air circuit but under all the hype and technical bulletins it is very simple.
It consists of airbags on each corner, valve block front and back centre valve block called reservoir block and a compressor also incorporating an exhaust valve. Joined by 6mm nylon air lines.
We can find leaks by removing lines from the blocks and pressurising them with a simple rig consisting of a pressure gauge and couplings.
I made the rig using an oil gauge oil gauge adapter and shrader valve for an alloy wheel.
Cut the mushroom head off the valve and it fits in the adapter.
The threads on the couplings are 1/8 BSP compatible, same as the oil gauge adapter.
The adapter is intended to replace the oil pressure switch to install a guage, the pressure switch screws in the side.
To test the components we need to remove the appropriate line from the reservoir block by unscrewing the Voss connector, the block comes off the chassis by pushing up to release the mounting grommets from the bracket.
Lubricate round the pipe first with WD40 etc.
The voss connector will screw into the block but will not tighten down on the olive, this is not a problem for test as the olive is tight on the pipe and tapered, the O ring seal is in the body so will not leak.
For example remove the line feeding the front suspension, expect air release, although its probably empty, which is why we are here, use safety glasses.
Screw the voss connector into the gauge block and pressurise with tyre inflator or compressor to 4 or 5 bar, read the gauge pressure and leave for a period.
If the pressure drops you have found the leak.
The air bags can be tested by removing the appropriate line from front or back valve block.
The compressor and exhaust valve by removing the compressor line at the reservoir block and pressurising the compressor.
find leaks with soap and water.
Repairs can be carried out with push fit 6mm connectors and airline available from flybay or the famous rain forest.
An alternative jig is to use a cheap tyre inflator and appropriate couplings.
The 6mm airline will make a good seal to the type clip if it is wound tightly with about 6 layers of electrical tape, wind it from the tape roll it must be tight and flat.
Pressurise as above and leave to find leaks if the pressure drops
Click image to enlarge
Click image to enlarge
If you remove a voss connector carefully open the split olive with a screwdriver, don't open it more than required to ease it off or it will crack.
If you replace any voss with EDIT 6mm x M10 x 1 push fit connectors or use straight couplers to repair test for leaks, carefully use PTFE plumbing tape.
some new fittings leak under pressure.
My leak was the line to the front valve block chaffed behind the nearside wheel arch liner.
If you chase this line, no need to remove the whole liner remove the front and outer clips to the centre
nearside and bend it down.
To access the front valve block remove the front third clips on the offside and bend the liner up.
Happy leak hunting, I hope this helps members find air leaks, there is no magic in the air circuit.
Regards
Bob
30th Aug 2020 9:11 am
Breg90
Member Since: 04 Feb 2017
Location: Falkirk
Posts: 348
Quality investigation and write up there!Series one 1949 - in bits, chassis is strapped to the ceiling in my garage (beside the canoe)
LR 90 - In bits
Disco 3 - currently in bits
Cheers Breg90,
Thanks for the complement.
I hope it helps members diagnose and fix problems and realise it is easy to do.
I also found leaks on every push fit on my "new hitachi compressor" which is actually a clone, using this method, and a leaking delivery valve on the last one I removed.
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