P38A EAS dropping at rear

Datatek said:

The plus 1.5" may well be due to weight transfer as the front left dropped a lot.

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pwood999 said:

This morning the Front Left was significantly lower than all the others, so leak has moved from back to front !! Using my manual control box, I re-inflated FL again, and the RR dropped back to where it was last night. So rear leaks improved, but not perfect yet.

Much soapier water, and finally found a slow leak bubble on front left outlet on valve block. Air-bag connectors have no leaks at all. Manged to re-seat the line, and no bubbles so far, but I suspect that vibration while driving wont help.

As all the airlines have nicks & scratches from years in the collets, I'm gonna do them in stages. First step will be replace the last few inches at the valve block & join them using compression fittings rather than push fit. If this works then no need to replace the entire airline, plus I then have easy disconnect joints near the valve block.

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Datatek said:

Are the compression fittings made for plastic pipe? The plastic push fit work well in my experience with commercial air powered systems.

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pwood999 said:

Thanks for the picture. Did you have to heat the airline and then push into the former ?

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wammers said:

As said many times, the only things about a solenoid valve that can cause a corner to drop is a leak on the small O'ring under the valve seat or the solenoid end seal. Every other O'ring on a solenoid valve can only leak when the corner being filled with air.

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pwood999 said:

Agreed, which is why I bench tested the valve block fully. Doesn't explain the rear rising overnight though.

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wammers said:

Inlet valve possibly leaking pressurising gallery and overcoming weak or damaged rear solenoid valves.

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pwood999 said:

That's what I was looking for on the bench test. With 100psi at tank connection, and 60psi on corner outlet, the gauge didn't move at all. But then on the car the tank is 30psi higher, and the 1/2 inch rise was overnight.

For now I'm focussing on sorting the airlines where they enter the block, and not worried about 1/2" over 12 hours !!

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pwood999 said:

While I'm waiting for the compression fittings, today I re-checked the output on both my pumps. They seem to achieve >150 psi with gauge directly on the pump, but on the car I can only get the tank to 125psi because the pressure switch stops the pump. Same thing happens on my spare valve block on the bench. Tried two pressure gauges but result is same within a few psi.

So it seems I have two duff pressure switches, that both close at 120-125 psi. Surely it should be >140 psi according to RAVE ? Do these things change with age.

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pwood999 said:

The problem is it opens again just under 120 so pump kicks in again. There’s supposed to be the 120-140 difference so small adjustments in height that only use a little air don’t cause the pump to continuously stop & start.

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