Member Since: 02 Feb 2008
Location: Warwickshire
Posts: 30
Pressure increases too slow when filling reservoir...
I really wasn't expecting this on my 2016 - D4 @ 40k miles but I keep getting the 'Only Normal Height Available' warning, along with CA120-64 (6C) plus UO421-68 (28) codes.
Using the GAP Tool, the Gallery Pressure 'normally' reaches 1777kpa from lower to normal level, in just less than 3 minutes.
However recently, it is sometimes taking up to 3.5 minutes, which I suspect is triggering the codes and warning.
All the four corner heights are approximately the same, stable over a few days when parked unused and with no apparent leaks.
So, I'm thinking, step one would be replacing the desiccant or opting for the repair kit?
Once I have removed the lower acoustic cover, will I be able to tell which compressor, etc is fitted, without actually removing it? So that I can order the correct whatever.
Or am I heading up the wrong path? 😉
Thanks 👍
13th Mar 2022 1:15 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5044
The compressor is part of the service schedule, so yes inspect/replace the desiccant and filters as it's likely they're shot by now. You should expect to see an AMK compressor when you remove the cover. Leave the pistons and cylinder seals alone and just focus on the desiccant and cleaning the exh valve.
It's possible you could have a reservoir leak though less likely. Use a small brush and air line if available to clear any detritus from the top of the reservoir, as this is where crud gathers and becomes wet eventually eating through the tank wall. yµ (idµ - eAµ) ψ=mψ
13th Mar 2022 3:25 pm
skipyskiphire
Member Since: 02 Feb 2008
Location: Warwickshire
Posts: 30
Thank you PROFSR G, that all makes sense and is very helpful 👍
I assume I will need to completely remove the Compressor from the vehicle to access the Air Dryer?
13th Mar 2022 8:53 pm
PROFSR G
Member Since: 06 Mar 2017
Location: Lost
Posts: 5044
Yes you can remove just the drier if preferred, it's easier to do on the AMK which will bring the exh valve with it. The Hitachi has a grub screw, but it's doable also.
Personally I just remove the complete unit for inspection and cleaning, but I leave the bracket in place as the bolts can often be rusted and seized.
See what unit you have fitted and it's condition, then go from there. yµ (idµ - eAµ) ψ=mψ
13th Mar 2022 11:11 pm
skipyskiphire
Member Since: 02 Feb 2008
Location: Warwickshire
Posts: 30
Thanks again 👍
Message received, understood and much appreciated!
14th Mar 2022 9:12 pm
skipyskiphire
Member Since: 02 Feb 2008
Location: Warwickshire
Posts: 30
Update....
I opted to remove the whole unit (which I'd recommend). There was a little white crud/powder on the dryer, so I dismantled it. There was a very small amount of moisture in the bottom of the blue inner casing and between the inner and outer casings but the desiccant 'looked' dry and the filters were slightly soiled.
I purchased 4x4 Air Seals AMK 'Air Suspension Compressor Air Dryer Filtration Standard Repair Kit excluding Electrical Exhaust solenoid' and following their instructions, cleaned and replaced the filters, all O rings and I cleaned both the exhaust ports of a little white grease.
The solenoid 'looks' fine and I sprayed a little contact cleaner into the centre as instructed.
Alas, on my outward journey last night, the warning message appeared again 😒 but it never appeared on my return journey a few hours later.
The Gallery Pressure 'normally' reaches 1776kpa from lower (238kpa) to normal level, in around 3 minutes.
However, sometimes it may take up to 3.5 minutes (from 143kpa to 1777kpa), which seems to trigger the codes and warning.
I've checked this morning and again, all the four corner heights are approximately the same, the gallery pressure was 240 last night and 234kpa this morning. The tank looks in good condition and there are no apparent or audible air leaks.
Is there a way of 'testing' both the compressor and the solenoid?
Or where to go from now?
Many Thanks 👍
20th Mar 2022 11:01 am
Disco_Mikey
Member Since: 29 May 2007
Location: Dundee, Scotland
Posts: 20842
Find somewhere quiet, fill the table to 18bar, switch engine off and listen carefully
If the reservoir was effectively empty overnight, there is a leak somewhere My D3 Build Thread
Member Since: 02 Feb 2008
Location: Warwickshire
Posts: 30
Many Thanks
Trouble is, I'm not sure what is 'normal' on these readings or what noises are normal
It is very quiet inside my garage, so I started the car, lowered it to access height (exhaust valve shows 100% then 0%). At this point, the Gallery Pressure shows 221kpa which then very slowly rises to 255kpa (without the compressor switching on).
I then raise the car to Normal Height. The Reservoir Valve opens to 100%, the Gallery Pressure shoots straight to 1300kpa, the car rises swiftly to Normal Height and the Gallery Pressure rises to 1776kpa in just over 3 minutes (3:02), at which point the Reservoir Valve returns to 0%, the Compressor stops and the Gallery Pressure drops straight down to 330kpa but then very slowly creeps up to 460kpi over about 5 minutes.
Once the ignition was turned off, the only noise I could hear was a very quiet but high-pitched whistle (which may have incorporated a hiss too) which seemed to originate from the area between the engine and the main battery compartment, I'd guess about the same height as the bottom of the battery compartment and about 10cm in.
This noise stopped after a few minutes when the was a short electronic whirr followed by a relay noise from the fuse box next to the battery.
Then it was as quiet as a ghost (to my ears), no matter where I lay or listened.
When I switched on the ignition after a few minutes, the Gallery Pressure was 460kpa and when I checked 15 minutes later, the pressure was 477kpa.
What part of all this is normal?
Cheers
20th Mar 2022 2:15 pm
Disco_Mikey
Member Since: 29 May 2007
Location: Dundee, Scotland
Posts: 20842
Right, OK. If gallery pressure jumps straight to 1300kPa, then its likely not a leaking air tank
The gallery pressure should be 100kPa (ish) in a perfect world, but normally 200-250kPa is normal. Any higher is indicating a leaking valve block seal, whether front, rear or centreMy D3 Build Thread
Member Since: 02 Feb 2008
Location: Warwickshire
Posts: 30
Thank you 👍
So, with reference to my previous message(s), is there any advice on how I should proceed?
Is there a test for the solenoid or compressor, etc?
21st Mar 2022 9:13 am
skipyskiphire
Member Since: 02 Feb 2008
Location: Warwickshire
Posts: 30
After a lot of help from PROFSR G, for which I am very, very grateful, despite the low mileage (41k), the solution to this problem ended up being (fingers crossed) a new AMK Air Compressor.
If any other Members have similar symptoms or have doubts about the performance/efficiency of their AMK Air Compressor and have access to the Gap IID Tool or a similar Diagnostic Tool (Live Values), as a rough guide, 'my' old compressor filled the reservoir at around 9kPa/second, whereas the new one fills at around 30kPa/second.
We also found an anomaly in the measurement that the IID Tool displayed for the ‘Reservoir Pressure Sensor Supply Voltage’, in that it remained constant at 0.980 volts, whereas the voltage measured with a DMM at the ‘out’ pin on the Air Suspension Control Module and the Pressure Sensor plug shows 5.0 volts with good continuity between all three wires on the Control Module plug and the Pressure Sensor plug (Supply Voltage, Pressure Sensor Signal Voltage & Earth).
This anomaly proved to be a red herring and played no part in the cause of the Air Compressor fault.
21st May 2022 1:28 pm
Browny90
Member Since: 19 Jul 2016
Location: Ashbourne
Posts: 698
Hi Just a quick one, please can you tell me where you got your new compressor from?
I have exactly tgr same issue on my 2016 Landmark, higher milage though.. ~75k..
So ill probably just replace the compressor as a start point as the age and milage would suggest it's that anyway..
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