R

Rudolf

Member
Evening guys.

So…. A couple of weeks ago I noticed the EAS pump running a lot in short bursts. From start up or from any height increase it runs on and off in about 4 second bursts, this might go on for 15 minutes before it settles down. In all other respects the system works perfectly. I can’t find any leaks and she doesn’t lose height when parked. I rebuilt the compressor but to no avail. Do any of the esteemed fraternity have any thoughts?
 
Rudolf said:
Evening guys.

So…. A couple of weeks ago I noticed the EAS pump running a lot in short bursts. From start up or from any height increase it runs on and off in about 4 second bursts, this might go on for 15 minutes before it settles down. In all other respects the system works perfectly. I can’t find any leaks and she doesn’t lose height when parked. I rebuilt the compressor but to no avail. Do any of the esteemed fraternity have any thoughts?
Click to expand...
Is this with the bonnet open?
 
Loose wire? Have you tried recording a trace using diagnostics?
 
Will it not show which circuits are open and if it really is running erratically? I'm thinking thermal switch here.

Guess worn brushes might also cause sporadic start-up. Or dodgy connector block.
 
Grrrrrr said:
Will it not show which circuits are open and if it really is running erratically? I'm thinking thermal switch here.

Guess worn brushes might also cause sporadic start-up. Or dodgy connector block.
Click to expand...

Compressor circuit is a bit basic on diag. If the thermal switch is duff it's usually totally duff it does not do a slight fail usually. Checking connections to pressure switch maybe an idea, that is the only thing in the valve block that has any effect on the compressor circuit. Even then it's an indirect link. The pressure switch has a narrow working band, compressor on 120 psi +- 7 psi. Off 140 +- 7 psi. So if it's getting duff the differential on to off, off to on can be quit low. Or quit high if it has varied in the other extreme. You would need a slight leak as suggested earlier to spring it into action though.
 
wammers said:
Compressor circuit is a bit basic on diag. If the thermal switch is duff it's usually totally duff it does not do a slight fail usually. Checking connections to pressure switch maybe an idea, that is the only thing in the valve block that has any effect on the compressor circuit. Even then it's an indirect link. The pressure switch has a narrow working band, compressor on 120 psi +- 7 psi. Off 140 +- 7 psi. So if it's getting duff the differential on to off, off to on can be quit low. Or quit high if it has varied in the other extreme. You would need a slight leak as suggested earlier to spring it into action though.
Click to expand...
RAVE gives a cut in pressure of 104 to 116 psi cut out pressure 138 to 152 psi so maximum differential is 48 psi, minimum differential 22 psi.:)
 
Datatek said:
RAVE gives a cut in pressure of 104 to 116 psi cut out pressure 138 to 152 psi so maximum differential is 48 psi, minimum differential 22 psi.:)
Click to expand...

Suppose that depends on which part of RAVE you read. Pressure switch in electrical diagrams is listed as low 8.5 bar 120 psi and high 10 bar 140 psi. Actually 8.5 bar is 124.95 psi and 10 bar is 147 psi. So i think for illustrative purposes the round 120 and 140 works pretty well. I mean Land rover don't even know that a bar is 14.7 psi so you can't expect total accuracy everywhere. :D:D
 
wammers said:
Suppose that depends on which part of RAVE you read. Pressure switch in electrical diagrams is listed as low 8.5 bar 120 psi and high 10 bar 140 psi. Actually 8.5 bar is 124.95 psi and 10 bar is 147 psi. So i think for illustrative purposes the round 120 and 140 works pretty well. I mean Land rover don't even know that a bar is 14.7 psi so you can't expect total accuracy everywhere. :D:D
Click to expand...
120+/-7 psi & 140+/- 7 psi could give a differential of as little as 6 psi, pretty unlikely I think, there is no indication of pressure in the wiring diagrams in my version of RAVE.
 
Last edited:
Datatek said:
120+/-7 psi & 140+/- 7 psi could give a differential of as little as 6 psi, pretty unlikely I think
Click to expand...

Unless you have a slight leak on NRV1 and the pressure switch is duff then you may get compressor running quit often don't you think?
 
The quoted 8.5 bar is 124.95 psi. -7 = 117.95 psi. +7 = 131.95 psi. 10 bar is 147 psi. -7 = 140 psi. +7 = 154 psi. So the highest differential can be 36.05 psi and the lowest 8.05 psi. :);)
 
wammers said:
The quoted 8.5 bar is 124.95 psi. -7 = 117.95 psi. +7 = 131.95 psi. 10 bar is 147 psi. -7 = 140 psi. +7 = 154 psi. So the highest differential can be 36.05 psi and the lowest 8.05 psi. :);)
Click to expand...
RAVE quotes a cut in figure in Bar of 7.8 to 8 bar (114.6 to 117.6 psi), cut out 9.5 to 10.5 bar (139.65 to 154.35 psi) based on your figure of 1 bar = 14.7 psi. Minimum hysteresis 22psi. Nowhere in my versions of RAVE does it mention +/- 7 psi.
An 8 psi hysterisis would be pretty ridiculous, the pump would be cutting in and out all the time.
 
Datatek said:
RAVE quotes a cut in figure in Bar of 7.8 to 8 bar (114.6 to 117.6 psi), cut out 9.5 to 10.5 bar (139.65 to 154.35 psi) based on your figure of 1 bar = 14.7 psi. Minimum hysteresis 22psi. Nowhere in my versions of RAVE does it mention +/- 7 psi.
An 8 psi hysterisis would be pretty ridiculous, the pump would be cutting in and out all the time.
Click to expand...

Somebody should have told the technical illustrator who did the wiring diagrams then. And advised him what a bar was. To many anomalies and contradictions. So if the compressor is supposed to cut off at between 9.5 bar and 10.5 bar. Nominal would be 10 bar, half a bar is 7.35 psi. Near enough to +- 7 psi for me. Seeing as Land rover seem to think a bar if 10 bar = 140 psi is 14 psi it would be exactly +- 7 psi what do you think? Get your glasses on lower figure is 7.2 to 8 bar.
 
Last edited:
Datatek said:
120+/-7 psi & 140+/- 7 psi could give a differential of as little as 6 psi, pretty unlikely I think, there is no indication of pressure in the wiring diagrams in my version of RAVE.
Click to expand...

Look at the diagram for the pressure switch. It states [0] < = 8.5 bar 120 psi. [1] > = 10 bar 140 psi. Every version of RAVE shows this from 1995 to the last one edition 20.
 
Last edited:
You must log in or register to reply here.

Similar threads

B
P38A P38A 1996 4.6 Auto HSE EAS slow to lower and rise + random height change to extended height + compressor running too frequently.
Replies
9
Views
1K
Datatek
Datatek
Flossie
P38A Eas issues
2
Replies
22
Views
1K
Datatek
Datatek
Montyjohn
P38A Adding a valve to manually fill EAS tank and why did my pump fail again?
Replies
14
Views
960
Datatek
Datatek
J
P38A p38 EAS - immediate drop of pressure
Replies
11
Views
627
Mark Piercy
Mark Piercy
B
P38A EAS compressor running almost continuously
Replies
7
Views
2K
Mark Piercy
Mark Piercy