Druim · Sep 12, 2014

wammers said:
You answered to quickly. And your point is?

If you want to be accurate, be closer to the accurate

no offense but I know about pressure, may be down on other points
FYI: Doing fiscal measurements on oil/gas/BS&W at work and need to be accurate, sometimes as high as 700 Bar the numbers makes a huge difference
Apart from that, not really fussed

To me 14.5 is fine but 14.7 what the hell it isn't fiscal

:kettlepot:

wammers · Sep 13, 2014

Druim said:
If you want to be accurate, be closer to the accurate no offense but I know about pressure, may be down on other points
FYI: Doing fiscal measurements on oil/gas/BS&W at work and need to be accurate, sometimes as high as 700 Bar the numbers makes a huge difference
Apart from that, not really fussed To me 14.5 is fine but 14.7 what the hell it isn't fiscal:kettlepot:

If you used 14.7 you would be erring on the side of caution. At 700 bar whats 140 psi amongst friends. Point is Land rover seem to have had several people using different versions of bar. Which makes people that get easily confused more confusedider.

Druim · Sep 13, 2014

Workshop manual, fairly accurate
Mounted on the valve block is a pressure switch which
senses air pressure and signals the ECU to operate
the compressor when required.The compressor will
operate when the pressure falls between 7.2 and 8.0
bar (104 and 116 lbf/in2). It will cut out at a rising
pressure of between 9.5 and 10.5 bar (138 and 152
lbf/in2).

From electrical diagran, - not that accurate
8.50 Bar - 120 psi
10 Bar - 140 psi

Worst case holding the two together hysteresis = 18 psi (WSM = 22 psi)

All in all, the pressure switch used are not the best or mounted in wrong position, tank location would probably be better

wammers · Sep 13, 2014

Druim said:
Workshop manual, fairly accurate
Mounted on the valve block is a pressure switch which
senses air pressure and signals the ECU to operate
the compressor when required.The compressor will
operate when the pressure falls between 7.2 and 8.0
bar (104 and 116 lbf/in2). It will cut out at a rising
pressure of between 9.5 and 10.5 bar (138 and 152
lbf/in2).

From electrical diagran, - not that accurate
8.50 Bar - 120 psi
10 Bar - 140 psi

Worst case holding the two together hysteresis = 18 psi (WSM = 22 psi)

All in all, the pressure switch used are not the best or mounted in wrong position, tank location would probably be better

Correct a bit misleading. However if i am in an airliner landing at a high level air field in fog i hope the altimeter is using 14.7 as a reference.

Rudolf · Sep 16, 2014

Thanks for all the suggestions guys, to be honest I'm not seeing much which fits the symptoms though. I thought about the thermal cut off and pressure switch, but why does it settle down after a while? I did wonder if there might be a constriction in the pump to tank circuit, such that the pump cuts in the local circuit builds up pressure and the switch cuts out, then the pressure bleeds away to the tank and the cycle repeats, eventually the tank is up to pressure and the pressure is held and the pump switched off. that would fit the symptoms, but is it a likely scenario? I'm not that familiar with the inside of the valve block. In answered to the questions asked. no the bonnet isn't open, this is whilst driving and no I haven't rebuilt the valve block, although I have considered it.

mozz smith · Sep 16, 2014

HI , How long have you owned this beasty ???

Datatek · Sep 17, 2014

Rudolf said:
Thanks for all the suggestions guys, to be honest I'm not seeing much which fits the symptoms though. I thought about the thermal cut off and pressure switch, but why does it settle down after a while? I did wonder if there might be a constriction in the pump to tank circuit, such that the pump cuts in the local circuit builds up pressure and the switch cuts out, then the pressure bleeds away to the tank and the cycle repeats, eventually the tank is up to pressure and the pressure is held and the pump switched off. that would fit the symptoms, but is it a likely scenario? I'm not that familiar with the inside of the valve block. In answered to the questions asked. no the bonnet isn't open, this is whilst driving and no I haven't rebuilt the valve block, although I have considered it.

Just a thought, is there a lot of clicking from the valve block when the compressor runs too often? If so it could be a dodgy height sensr assuming leaks have been eliminated, otherwise fit new O rings to the valve block and pay particular attention to the non return valves, also check/replace the diaphragm.

Rudolf · Dec 26, 2015

Merry Christmas one and all. Just for completeness I should say (albeit rather late) that Datatec hit the nail on the head. Checking the height sensors revealed erratic responses from the OSF and changing that solved the problem! I think it was just changing height all the time and running out of air, although you could not see any real height change. Onwards and upwards to the next problem, see new thread on blend motors...

Druim

Well-Known Member

wammers

No longer with us, RIP

Druim

Well-Known Member

wammers

No longer with us, RIP

Rudolf

Member

mozz smith

Well-Known Member

Datatek

Well-Known Member

Rudolf

Member

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