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View Full Version : Help with compressor/suspension issue please


hpal
2nd January 2023, 05:06 PM
Hi All,
I've had a bad run with the disco lately, but need some help with air suspension issues. I thought I had a front valve block leaking so replaced it with a new genuine one, but turned out to be both Dunlop bags leaking (only 50,000kms) so replaced them with two new BWI brand Ines, now it doesn't drop overnight or at all, very good in that respect now. Then the compressor packed it in and I ordered a new Hitachi and fitted it. I also have a new centre air valve which I have not fitted yet. Now the new compressor ids behaving like the old one and doesn't seem to be cutting out when it should, I have also fitted a new genuine compressor relay which is working well too. If you would be so kind as to look at the YouTube video linked, you may be able to give me some clues. In this video I had dropped down to access height and the reservoir pressure was about 165 kph according to the Gap tool, then I flicked the height switch to go to normal height, the compressor cut in and built up to like 1800kpa then the compressor cut out on high temp (hope it hasn't done damage?)
The gallery pressure general running round was about 300 or 350 kpa which I thought would have been higher. Any height change seems to make the compressor run to 1800kpa then it shuts off and vents or something then the pressure settles in the two hundreds, just doesn't seem like enough and seems weird behaviour and same thing the old compressor was doing. I don't want to stuff this new compressor as it was very expensive. I'd appreciate and pointers if someone has come across similar before.
Should I change the centre reservoir valve for the new one maybe?
New hitachi compressor in d3 not behaving like it should - YouTube (https://youtube.com/shorts/ultOBv48ADk?feature=share)
DiscoJeffster
2nd January 2023, 05:15 PM
They have a high temp cutout and are designed to hit it. Once cooled enough it will continue to inflate to the desired height. They generally will not do more than one raise cycle before being too hot, which can be exacerbated if it’s also run through its startup tests etc.
BradC
2nd January 2023, 06:00 PM
This explains (mostly) how it generally works.

D3 EAS C1130-66 fault (https://www.aulro.com/afvb/l319-discovery-3-and-4-a/287454-d3-eas-c1130-66-fault-post3107860.html#post3107860)
hpal
3rd January 2023, 03:49 PM
They have a high temp cutout and are designed to hit it. Once cooled enough it will continue to inflate to the desired height. They generally will not do more than one raise cycle before being too hot, which can be exacerbated if it’s also run through its startup tests etc.
So crazy they designed a system that makes the compressor top out on high temp as part of normal running, and flog itself to death reaching 1800kpa only to then vent to 300! It can't be good for the piston seal. I don't remember (when my old one was running right) it staying on so long, do you know what the centre valve does, does it incorporate a relief valve and should I change the centre valve out in case it is giving me issues?
DiscoDB
3rd January 2023, 04:45 PM
The high temp trip is at 140degC when filling the reservoir back up (and 150degC when lifting). Under normal operation it shouldn’t hit the high temp trip.

When going from access height to normal height - my compressor runs the same and hits about 100degC on a 20degC day when filling the reservoir back up to something like 1750kpa.

Once at normal height - it holds that pressure (at least for the short time I was watching ) but I haven’t watched to see what is does once driving.
SeanC
3rd January 2023, 05:51 PM
I don’t think there is anything wrong with your compressor.
I have an AMK compressor with a slightly different algorithm than the Hitachi. You can choose the compressor brand with the Gap Tool.
Max. pressure is just over 1700kpa dropping to about 230kpa.
I ran 3 cycles of Access Height to Normal Height back to back.
First cycle form a cold start the compressor reached 60c
Second Cycle reached 80c.
Third cycle reached 92c
Your compressor took just over a minute.
Mine took just under 1 min 30 sec.
Your compressor is reaching a higher pressure in a significantly shorter time so I am not surprised it is generating more heat.
So I think all is as it should be.
josh.huber
3rd January 2023, 08:00 PM
I would change the Center especially if you have it. Mine goes up and down without any dramas, the centre valve does quite allot. If it's not fully shifting any valves, it'll be building up pressure and heat without filling the tank