P38 eas compressor excessive running SOLVED

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mgmayo

mgmayo

Active Member
Posts
133
Location
Co.Mayo, west of Ireland
Having had a 95DT which I have now parked as a donor/offroader as I bought a 98DHSE. Previous owner said he had fitted a new eas block and recon compressor. This I am happy with as they are labelled as such.
However I didnt have it long when the compressor started going on and on and on!! Sound familiar. I followed all the advice on here and changed the compressor etc. There are no leaks in the system.
However it persisted with the excessive running so I investigated the pressure side of things, doubting the pressure switch I looked at replacing it. While looking for an alternative, spurious part I discovered that the original engages the pump at 110 psi and switches it off at 145psi. I fitted a pressure guage in the cab to monitor the pressure and concluded that it builds easily to 120psi but struggles to get the last 25psi. I tried 2 more compressors incl a twin piston one with plenty of capacity but they also struggle to get to the high psi.
In sourcing an alternative switch I had to go look to USA sites. Most of these sites noted that a normal air suspension should not run higher than 120psi or it will excesssively shorten its life. Therefore I got an adjustable switch. I now have that set to 100psi cutoff for the compressor and all works well with the compressor not coming on often or for long. Food for thought?
I have tried to source a similar or fixed range switch(120off 90on) in Ireland and UK but cannot find one that I can recommend.

I hope my story can inform/help someone out there
 
mgmayo said:
Having had a 95DT which I have now parked as a donor/offroader as I bought a 98DHSE. Previous owner said he had fitted a new eas block and recon compressor. This I am happy with as they are labelled as such.
However I didnt have it long when the compressor started going on and on and on!! Sound familiar. I followed all the advice on here and changed the compressor etc. There are no leaks in the system.
However it persisted with the excessive running so I investigated the pressure side of things, doubting the pressure switch I looked at replacing it. While looking for an alternative, spurious part I discovered that the original engages the pump at 110 psi and switches it off at 145psi. I fitted a pressure guage in the cab to monitor the pressure and concluded that it builds easily to 120psi but struggles to get the last 25psi. I tried 2 more compressors incl a twin piston one with plenty of capacity but they also struggle to get to the high psi.
In sourcing an alternative switch I had to go look to USA sites. Most of these sites noted that a normal air suspension should not run higher than 120psi or it will excesssively shorten its life. Therefore I got an adjustable switch. I now have that set to 100psi cutoff for the compressor and all works well with the compressor not coming on often or for long. Food for thought?
I have tried to source a similar or fixed range switch(120off 90on) in Ireland and UK but cannot find one that I can recommend.

I hope my story can inform/help someone out there
Click to expand...

If the compressor struggles to raise pressure over 120 psi it is duff simple as that. If a gauge is connected to the compressor outlet a standard compressor in good condition should produce 170 psi + within seconds of start up. If a compressor will not do that it is faulty. This significant differential above system working pressure is needed, or full working pressure will be very slow to build.
 
wammers said:
If the compressor struggles to raise pressure over 120 psi it is duff simple as that. If a gauge is connected to the compressor outlet a standard compressor in good condition should produce 170 psi + within seconds of start up. If a compressor will not do that it is faulty. This significant differential above system working pressure is needed, or full working pressure will be very slow to build.
Click to expand...
Either what Wammers has said or there is a leak possibly on the storage side.
Lowering the pressure lowers the response time of the system.
 
Hi guys,
Yes I agree with your info and had tested for the 170psi performance. One of the 3 compressors i was using was performing to this. In the original setup the storage side was not leaking as the comp would come on first thing in the day. But after a bit of travelling it would and struggle to get to the 145. While i am now running at 100 psi I dont notice any differance in normal running. If I want to go to offroading height yes it is slightly slower, or also if going from access to normal. However these are settings that are not often used. My experimenting was in an effort to see if the high pressure was required. Yes a good compressor will do 170psi but it will wear out quicker when running at 145psi than at say 120psi. Figures on a USA site selling comparable compressors say they will work at 145 for 25% duty cycle while at 120 its 60%. Therfore of course it will last all the longer. There are countless posts on here with frustrated owners due to failing compressors. While my point is by running at the lower pressure it will last far longer with adequate performance. I had similar problems on the 95DT which I never got to the bottom of, also a friend with a 2001 model has replaced his bags, block and comp but is haunted by the regular long/hot running of the comp. Sorry for the long winded explanation. I hope tomorrow to do a video to show the system running as low as 80psi.
 
If the EAS system is in good order, the compressor does not run excessively and will last 10 years or so.
What you have done is a bodge IMO to avoid fixing a problem. It may mask the problem for a while or it may bite you when it is most inconvenient.
The airbags only require 50 to 60psi at normal ride height unladen so it will of course come up to height, albeit slowly with your reduced pressure.
Given that LR spent millions developing the system, I wonder why they did not think of running at a lower pressure?:rolleyes:
 
Can only agree with datatex here.

I had 500kg of stuff loaded in the back of mine today and it raised from lowest position to normal in no time
Would like to see it try at reduced pressure..
 
I got from airbagit.com usa, I don't think they ship abroad I got it via a friend. Part no.
AIR-PRESSURE-SW-00
I can't get suitable one over here. This is adjustable, again I would go for a 120psi.
Otherwise no signs of leaks on block. It was a recon unit 2yrs ago. However I do intend to rebuild the block from the 95dt and fit it sometime. However now that I am working at lower pressure it doesn't bring on the comp very often so maybe no leaks just a failing comp.
 
I think this is a good solution. I have thought about it too. I agree that we need to chase leaks as a priority though.

However, the chance of leaks, due to the strain on every seal is much higher at 150psi than it is at 120psi. In fact, even though I have rebuilt my valve block twice, and have new GenIII springs, my 150psi leaks down to 130 each night. I too have a gauge in the dash. If it continued to leak down past 130 I would be very concerned; and solve an actual leak, but its sits at 130 for days, so I figure that the imperfection/issue is not a catastrophic one.

All I am doing now is making the pump run from 130 to 150 every single time I drive, when it may rarely have to run if the shut off was 130. The system works perfectly otherwise.

Thanks for your post.
 
glenhendry said:
I think this is a good solution. I have thought about it too. I agree that we need to chase leaks as a priority though.

However, the chance of leaks, due to the strain on every seal is much higher at 150psi than it is at 120psi. In fact, even though I have rebuilt my valve block twice, and have new GenIII springs, my 150psi leaks down to 130 each night. I too have a gauge in the dash. If it continued to leak down past 130 I would be very concerned; and solve an actual leak, but its sits at 130 for days, so I figure that the imperfection/issue is not a catastrophic one.

All I am doing now is making the pump run from 130 to 150 every single time I drive, when it may rarely have to run if the shut off was 130. The system works perfectly otherwise.

Thanks for your post.
Click to expand...

If it goes down from 150 to 130 each night either the connection on the tank, the pipe or tank itself is leaking or the threads on the pressure switch, blow off valve, but most likely NRV1 or the o'ring sealing it to the block is leaking. The pressure storage side is very simple to diagnose there are not a lot of areas it can leak.
 
Interesting. Surprised at how fast it responded with the lower pressure. If no air is escaping I struggle to see why the compressor will last longer though. I also have a 1995 DT with a pressure gauge fitted (not that it makes much odds as the air system has had most of it replaced at one stage or another) and my compressor kicks in at (IIRC) about 130 - 135 psi. However, it only runs for a little while each time. I lose no air overnight at all. This is the second pressure switch - not statistically significant but at least it is consistent! I'll let you know when my compressor next needs a refurb. Been in there a while now.
 
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