P38A EAS dropping at rear

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After refurbishing my spare valve block found the exhaust valve was leaking at the rate of one bubble per five mins !! Sorted that, but wanted to do an overnight test. Got these gauges on eBay for £30 for all five. Used my garage compressor as the ar tank (I know it holds air for weeks), and loaded the four corner gauges with 60 psi, and left the tank port at 100 psi. Much easier than watching soapy water for hours on end !!

18 hours later, all 4 corners are same pressure, and -5 psi on tank port. I suspect it's the tee-piece or other joint, but might be Inlet valve plunger wear.

Valve Block Leak Test.JPG
 
pwood999 said:
After refurbishing my spare valve block found the exhaust valve was leaking at the rate of one bubble per five mins !! Sorted that, but wanted to do an overnight test. Got these gauges on eBay for £30 for all five. Used my garage compressor as the ar tank (I know it holds air for weeks), and loaded the four corner gauges with 60 psi, and left the tank port at 100 psi. Much easier than watching soapy water for hours on end !!

18 hours later, all 4 corners are same pressure, and -5 psi on tank port. I suspect it's the tee-piece or other joint, but might be Inlet valve plunger wear.

View attachment 217900
Click to expand...

I like that. Did the guages come with adapters? Presumably they require batteries?
 
Grrrrrr said:
I like that. Did the guages come with adapters? Presumably they require batteries?
Click to expand...

The gauges are 1/8 NPT, so I bought some NPT-BSP adapters so I could use my existing 1/8 BSP push-fits. Fitted them with Loctite 577 so no leaks.

Yes they need 2 x AAA batteries each. They power up when you press a button, or apply pressure. Cannot seem to switch off while pressure is applied, so all five have been on for 24 hours now & still showing full battery indicator !! The blue light goes off after 5 mins, but display is still active.

Planning to mount them on a board, so if necessary will build a small 3V PSU.
 
pwood999 said:
The gauges are 1/8 NPT, so I bought some NPT-BSP adapters so I could use my existing 1/8 BSP push-fits. Fitted them with Loctite 577 so no leaks.

Yes they need 2 x AAA batteries each. They power up when you press a button, or apply pressure. Cannot seem to switch off while pressure is applied, so all five have been on for 24 hours now & still showing full battery indicator !! The blue light goes off after 5 mins, but display is still active.

Planning to mount them on a board, so if necessary will build a small 3V PSU.
Click to expand...

I'll send my kit down there to be tested!
 
Update on this saga. After sorting all the seals on two valve blocks I have found the real cause of the issues, and there's several different issues.
  1. Scratches & wear on the air-bag airlines where they enter the valve block. Installed compression fittings in to valve block and now these joints are all good with threads also sealed with Loctite.
  2. Both blocks have internal valve leaks but different places.
    • Block-1 has a slow leaks internally through the rear corner valves to the main gallery, plus the exhaust valve. This allows the rear to sink a few inches overnight. Was easy to spot with tank pressure applied & exhaust valve removed. Normally the Inlet valve should hold tank pressure, but saw about 1 bubble per min from main gallery towards the exhaust valve.
    • Block-2 has a slow leak from the tank through the Inlet valve to the main gallery, plus a leak from rear right corner to the gallery. Consequently this corner equalises with the tank. Previously this block also had an internal exhaust leak allowing both tank & rear right to empty overnight. Fixed the exhaust valve so now the other valve leaks just equalise tank & right rear corner. The result depend on the pressure difference when the valves shut !!
Will add pictures to show the above later.

So with no leaks around the valve body sides, plunger seals or airlines, the real problem seems to be the valve plunger faces & probably weak springs. Inlet & Exhaust springs measure about 12mm, so ordered some 15x3mm springs to see if this helps. I will also try refacing the rubber to remove the circular dents we see on all valve blocks.
 
pwood999 said:
Update on this saga. After sorting all the seals on two valve blocks I have found the real cause of the issues, and there's several different issues.
  1. Scratches & wear on the air-bag airlines where they enter the valve block. Installed compression fittings in to valve block and now these joints are all good with threads also sealed with Loctite.
  2. Both blocks have internal valve leaks but different places.
    • Block-1 has a slow leaks internally through the rear corner valves to the main gallery, plus the exhaust valve. This allows the rear to sink a few inches overnight. Was easy to spot with tank pressure applied & exhaust valve removed. Normally the Inlet valve should hold tank pressure, but saw about 1 bubble per min from main gallery towards the exhaust valve.
    • Block-2 has a slow leak from the tank through the Inlet valve to the main gallery, plus a leak from rear right corner to the gallery. Consequently this corner equalises with the tank. Previously this block also had an internal exhaust leak allowing both tank & rear right to empty overnight. Fixed the exhaust valve so now the other valve leaks just equalise tank & right rear corner. The result depend on the pressure difference when the valves shut !!
Will add pictures to show the above later.

So with no leaks around the valve body sides, plunger seals or airlines, the real problem seems to be the valve plunger faces & probably weak springs. Inlet & Exhaust springs measure about 12mm, so ordered some 15x3mm springs to see if this helps. I will also try refacing the rubber to remove the circular dents we see on all valve blocks.
Click to expand...

Bubble? You have it in a liquid?
 
No soapy spray. Wait for picture.

But I did have the valve block ( minus electrics) fully submersed at one point. That’s how I found & fixed all the valve seal leaks.
 
pwood999 said:
Update on this saga. After sorting all the seals on two valve blocks I have found the real cause of the issues, and there's several different issues.
  1. Scratches & wear on the air-bag airlines where they enter the valve block. Installed compression fittings in to valve block and now these joints are all good with threads also sealed with Loctite.
  2. Both blocks have internal valve leaks but different places.
    • Block-1 has a slow leaks internally through the rear corner valves to the main gallery, plus the exhaust valve. This allows the rear to sink a few inches overnight. Was easy to spot with tank pressure applied & exhaust valve removed. Normally the Inlet valve should hold tank pressure, but saw about 1 bubble per min from main gallery towards the exhaust valve.
    • Block-2 has a slow leak from the tank through the Inlet valve to the main gallery, plus a leak from rear right corner to the gallery. Consequently this corner equalises with the tank. Previously this block also had an internal exhaust leak allowing both tank & rear right to empty overnight. Fixed the exhaust valve so now the other valve leaks just equalise tank & right rear corner. The result depend on the pressure difference when the valves shut !!
Will add pictures to show the above later.

So with no leaks around the valve body sides, plunger seals or airlines, the real problem seems to be the valve plunger faces & probably weak springs. Inlet & Exhaust springs measure about 12mm, so ordered some 15x3mm springs to see if this helps. I will also try refacing the rubber to remove the circular dents we see on all valve blocks.
Click to expand...
Think can supply new nrv's worth asking.
 
Last edited:
Wow gauges abound. You will be aware that a certain drop (from memory up to 25 mm) in a twenty four hour period is acceptable and within design spec.
 
Alan, the NRV's seem to be ok. No leak back through NRV-1 to Compressor or Diaphragm Valve.
Wammers, yes I know that 25mm is acceptable, but I have time to play during lockdown !!

Here's the pictures. Pressurised the Tank only, and I get bubbles at main gallery feeding corner valves. No leaks around the Inlet valve.

For some reason I have 4.0mm Exhaust & 2.5mm Inlet ?? Swapped them over using the 4.0 as Inlet, and it seems to seal better than the 2.5.
I cannot find anything online (here, rr.net or google), and none of the TSB's mention valve sizes.

1.Inlet Valve Internal Leak.JPG 2.Inlet+Exhaust Valve Size.JPG

After swapping the valves around, I also checked the exhaust silencer port with soapy water. There's no bubbles so I suspect the 2.5mm valve internal leak is not enough to open NRV-3 which is good on the bench, but eventually the pressure between Exhaust & NRV3 will open it & lose air.
 
pwood999 said:
Alan, the NRV's seem to be ok. No leak back through NRV-1 to Compressor or Diaphragm Valve.
Wammers, yes I know that 25mm is acceptable, but I have time to play during lockdown !!

Here's the pictures. Pressurised the Tank only, and I get bubbles at main gallery feeding corner valves. No leaks around the Inlet valve.

For some reason I have 4.0mm Exhaust & 2.5mm Inlet ?? Swapped them over using the 4.0 as Inlet, and it seems to seal better than the 2.5.
I cannot find anything online (here, rr.net or google), and none of the TSB's mention valve sizes.

View attachment 218322 View attachment 218323

After swapping the valves around, I also checked the exhaust silencer port with soapy water. There's no bubbles so I suspect the 2.5mm valve internal leak is not enough to open NRV-3 which is good on the bench, but eventually the pressure between Exhaust & NRV3 will open it & lose air.
Click to expand...

Ok play away. When you play you learn.
 
pwood999 said:
After refurbishing my spare valve block found the exhaust valve was leaking at the rate of one bubble per five mins !! Sorted that, but wanted to do an overnight test. Got these gauges on eBay for £30 for all five. Used my garage compressor as the ar tank (I know it holds air for weeks), and loaded the four corner gauges with 60 psi, and left the tank port at 100 psi. Much easier than watching soapy water for hours on end !!

18 hours later, all 4 corners are same pressure, and -5 psi on tank port. I suspect it's the tee-piece or other joint, but might be Inlet valve plunger wear.

View attachment 217900
Click to expand...
I would have fully refurbed your block so it worked as a brand new one for a very cheap price mate . If you ever need it doing.
tenor.gif
 
kurtjohnson10 said:
I would have fully refurbed your block so it worked as a brand new one for a very cheap price mate . If you ever need it doing.
tenor.gif
Click to expand...
Kurt,
I already replaced all the seals on both my valve blocks recently, including NRV o-rings & diaphragm valve. The only original parts remaining are the valve plungers & their springs and the NRV's themselves.

NRV-1 seems to be sealing ok, because when tank feed is pressurised, the only escape is past the Inlet & Exhaust valves. The other two NRV's only control the flow during air-bag inflation or deflation. There's some slight wear on the cone tips, so used the best one for NRV-1.

If you have valves with new rubber for better sealing that would be good ? I have done the refacing with emery on Inlet & Exhaust plungers on one block, and it seems to have held pressure for 48 hours, so better than before.

Pete
 
pwood999 said:
Kurt,
I already replaced all the seals on both my valve blocks recently, including NRV o-rings & diaphragm valve. The only original parts remaining are the valve plungers & their springs and the NRV's themselves.

NRV-1 seems to be sealing ok, because when tank feed is pressurised, the only escape is past the Inlet & Exhaust valves. The other two NRV's only control the flow during air-bag inflation or deflation. There's some slight wear on the cone tips, so used the best one for NRV-1.

If you have valves with new rubber for better sealing that would be good ? I have done the refacing with emery on Inlet & Exhaust plungers on one block, and it seems to have held pressure for 48 hours, so better than before.

Pete
Click to expand...
I have a full set of as new solenoids available Pete if you are interested :);).
 
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