P38 EAS DIAHAPRAM ISSUES

The EAS on my P38 has been source great pain lately it keeps blowing it's diahapram every few days. Resulting in air being pumped straight out exhaust valve. I'm at loss what try next I'm not getting any fault codes and been leaked tested. The parts I've replaced already are: Valve block both refurbed, driver pack, pressure switch, relife valve.

What happens is soon as replace diaphragm it works for day or 2 fine then same fault again. Could it be the ECU at fault? Need help as driving me mad.

Dab90 said:

The EAS on my P38 has been source great pain lately it keeps blowing it's diahapram every few days. Resulting in air being pumped straight out exhaust valve. I'm at loss what try next I'm not getting any fault codes and been leaked tested. The parts I've replaced already are: Valve block both refurbed, driver pack, pressure switch, relife valve.

What happens is soon as replace diaphragm it works for day or 2 fine then same fault again. Could it be the ECU at fault? Need help as driving me mad.

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ECU has nothing to do with the diaphragm valve. Have you left the spring out that goes below the diaphragm valve? When power is supplied to compressor the diaphragm solenoid is also activated. This directs air to below the diaphragm sealing it against the exhaust port in the fill/exhaust gallery. The spring must be present to provide an initial seal against the port until air pressure builds to seal it properly. Have you got the diaphragm the correct way up?

No the spring is fitted and the diaphragm right way round.

Dab90 said:

No the spring is fitted and the diaphragm right way round.

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Duff diaphragms then or solenoid is failing. Check that solenoid connections are sound.

Tried different diaphrams from different suppliers and 2 different solenoids.

Dab90 said:

Tried different diaphrams from different suppliers and 2 different solenoids.

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Has to be bad wiring connections then. The same relay that powers the compressor powers the solenoid. Check pins in the plugs.

The solenoid wiring and driver pack all good. I check out the relay.

Dab90 said:

The solenoid wiring and driver pack all good. I check out the relay.

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If the compressor is running there is nothing wrong with the relay.

Yeah pump runs the air just gets pumped out exhaust valve. Something in system causing it stick on both valve blocks it's had.

Are the NRV `s working

As far as I'm aware NRV working had sane issue on both valve blocks that just been refurbished. Anyway test NRV for certain?

Dab90 said:

Yeah pump runs the air just gets pumped out exhaust valve. Something in system causing it stick on both valve blocks it's had.

Click to expand...

The fill system, compressor, diaphragm valve, pressure switch, drier, NRV1, tank etc have nothing to do with any other part of system. They are a separate entity. All they are there to do is fill the tank as required. I will say again, when tank pressure drops below 120 psi as signalled by pressure switch ECU pulls compressor relay to power compressor, at the same time the relay also powers the diaphragm valve solenoid. The diaphragm valve diverts air to below the diaphragm to push it onto the exhaust port in the fill/vent gallery. Air then passes via a 8 mm pipe into the bottom of the drier. It then passes from bottom of drier to top and into valve block via another 8 mm pipe past NRV1 into the pressure switch gallery and to tank via a 6 mm supply pipe. When 140/150 psi is attained as signalled by pressure switch the ECU drops relay pull. The compressor stops and the diaphragm solenoid power is removed, it drops and vents air from under the diaphragm via a 4 mm pipe into the harness. This allows high pressure air from the fill/vent gallery to expel to atmosphere in the opposite direction of filling thus expelling any moisture collected in the drier whilst filling. Either the solenoid is not being powered because of bad connections, it is duff or incorrectly assembled simple as that.