P38A Help on EAS Problem

All,

Firstly apologies for the long thread, but thought I should provide as much info as possible.

I had my air pump pack up this week, the piston inside had broken - it would work but it sounded like a bag of bones and no air came out.
I had noticed recently that it had been getting very hot, but had been assured all was normal.
The car was not dropping on any side and settled overnight as expected, but not to the extent of being on its bump stops. However, if left, after a few days it would settle to Access height.
And no EAS or height sensor faults were showing on my Nanocom.
All bags have been replaced in the last year.

Anyway, I have a spare pump and have connected that. Suspension back up.

However, I was not entirely happy with the notion that it was just the pump that had packed up and not something else that has overworked the pump to cause it to pack up. So I decided to do some EAS checks as per the "How to" at the top of this forum.

1) Soapy water check all round shows no leaks and spare pump is working as it should.
2) Removed exhaust silencer with compressor/engine running and did test. Now I'm not sure sure if this should happen or not. The info says no air should escape from the exhaust, but after a short while I get a large spurt of air out (which made me jump first time!!) and the pump turns itself off. After few seconds the pump starts again and the same happens, etc. Is this correct or is my Diaphragm or the two sensors F*(ked!!?
3) Compressor cycles on and off frequently - With the engine running, and a door open, the pumps runs and then shuts down as it should, not restarting until I close the door. Not sure if it is the temp or pressure controlling this, but pump is not excessively hot so would assume pressure sensor doing its job.
4) No faults on Nanocom and used the EAS area of it to open/close valves and change heights, etc, etc. Everything seems correct.

After doing these tests, the EAS has settled down and seems to now be behaving itself.

So, now I am wondering if I have an intermittent fault with one of the bits in the Valve block being worn? It is nearly 17 years old!

1) Diaphragm - because of the air out of the exhaust outlet.
2) Temp Sensor - because of the compressor frequent running.
3) Pressure Sensor- because of the compressor frequent running.
4) NRV - because of the above.
5) All of them!!

As I have already ordered a Valve block kit and have a pressure sensor - would just need the temp sensor to complete the set!!

So, could there be anything else, other than a worn part in the valve block that could cause the playing up and could have contributed to the pump packing up.

Thanks in advance

It does sound very similar to my problem earlier this year. My original pump thermal switch failed so bought a refurbed pump only to find it ran too often & was concerned about another thermal switch fail - obviously loosing air somewhere. I found no leaks anywhere (valve block, pipes, dryer, tank, bags etc) & was getting despondent. I eventually bought a bargain refurbed valve block & all is well. At least i can rebuild my old block at my leisure.
PS, i'm pretty sure the exhausted air from the exhaust port when the pump stops is normal operation as it's excess pressure being expelled.

I think the air from the exhaust when the pump stops is normal, it blows the dryer clean.sure I read that somewhere, then again it may be old age trying to catch up with me.

Yes the burst of air from exhaust port is definitely normal. They all do this. It's mainly the residual air between the diaphragm and the NRV+Dryer+Pump lines. So when the pump stops & diaphragm operates (same relay), then air dumps and the NRV closes under tank pressure. Air circuit is in the EAS Sys Info Doc.

Main thing to check there is no air leaking from the exhaust when the pump is not running. Internal leaks within the valve block between the different air circuits will cause pump to run more frequently, so worth fixing considering how cheap the kits are. BUT always use the better quality nitrile o-rings, and thoroughly clean any residual dryer dust from the block.

FYI, I left my exhaust silencer off for a few days as a way to monitor the pump cycling on & off, but it gets annoying after a while. Doesn't hurt anything doing this though.