EAS Diaphragm Valve question

[p38arover]

It was a toss up whether to put this question here or in Technical Chatter. It relates to both RRC and P38A EAS valve blocks. Mods feel free to move it to TC if you think it should go there.

I did a valve block rebuild back in June just before my trip to Echuca and all was well. However, two days into the trip I found the compressor couldn't keep up with air loss. It took a while to find it but I did. I have a problem with air leaking out of the exhaust port as the pressure builds. So I had to swithc off the EAS and rely on inflating the airsprings manually

The EAS SID pointed toward the diaphragm valve as the culprit as did my examination of the EAS block diagram.

Research on the 'net indicates the diaphragm valve is prone to failure. But what type of failure? I've pulled mine out and can see no faults with it and it is 20 years old.

I tried a replacement but the air still leaked out. I'm starting to think the NRV on the air tank line has failed. It appears to be the only other thing that can fail and supply air to the exhaust port (assuming the suspension stays up). I'll pull it out and replace the O-rings again tomorrow.

What I'd also like to know is how the diaphragm valve itself works. Looking at it, it's operation isn't obvious and, reading PaulP38A's notes, it looks like it can be replaced with a simple rubber disc so it isn't a complex thing.

[ian4002000]

Whilst locating problems with my EAS I installed a y piece, tanks valve and a ball valve on the air tank line. This has enabled me to test and refill the tank easily and depending on where you put the valve may be able to stop the leak. If you can post a picture of the valve you suspect is leaking it may help me to supply more info. Most of the valves just have O rings and you should be able to find the leaking one with a spray bottle.
At one point in testing I pulled the valve block from the housing and manually pressurised it to check for leaks. This was really good for finding leaking O rings.
Ian
Bittern

[p38arover]

Hi Ian. I can manually inflate my system. I also have an EAS disable switch fitted.

There were no leaks from air lines - it was rushing out the exhaust silencer!

I pulled the valve block again and swapped the air tank NRV with another from the same valve block. The system is now holding air. I have no idea why the NRV was leaking, it had a new O-ring and didn't have any sticky lube on it.

I'll see how it goes over the next week.

[Boblofty]

Hi Ian. I can manually inflate my system. I also have an EAS disable switch fitted.

There were no leaks from air lines - it was rushing out the exhaust silencer!

I pulled the valve block again and swapped the air tank NRV with another from the same valve block. The system is now holding air. I have no idea why the NRV was leaking, it had a new O-ring and didn't have any sticky lube on it.

I'll see how it goes over the next week.

This may be a bit late Ron, but did your replace your 'O' rings with the red ones being sold on the net. After a number of rebuilds, I have discovered that the red ones (and they are touted as superior rubber), fail for some inexplicable reason, twice on the NRV's. Went back to the black originals as specd' by Land Rover and not a problem since.
Cheers Bob

[p38arover]

Hi Bob, no, the O-rings were black from kits supplied by Rover Renovations in the USA.