Air leak detection - EAS woes!

I’m sure this has been flogged to death and then some but I didn’t find a response to a similar question online and I’m pretty much just rambling out loud here but hopefully the huge knowledge base here will know. Can a leak on the EAS be detected using a UV type dye similar/the same as used on an AC system to nail down a leak? I’ve had a slow leak on my EAS for a wee while now and it needs addressed so as not to burn out my pump.

The situation - my EAS inflates as normal, works as normal (ignoring a recent pump failure prior to valve block rebuild), goes from empty tank to full tank in about 8-9 minutes or so with the door open etc, and crucially, the air bags do not lose any air at all overnight; no low corners indicating a bad bag and she will sit up nice and high for days on end with no problems. The tank however will have emptied itself to about 20 psi over say two days. This morning it was full at 130 psi and over 4 hours dropped to 90 psi. I’m monitoring this on my inline pressure gauge plumbed in on line 6 between the level block and the tank.

What I’ve tried - I found that about a few weeks ago my diaphragm valve in the valve block was leaking and air was moving back through valve block, through the air dryer and out into the air. This was found by the bubble mixture method. I’ve stripped the block down and did a full rebuild from X8R, using the Vaseline in the right places and it sealed it up nicely. I’ve been round and round the while system with more bubble mixture but haven’t found anything since despite this weep of air showing on my air pressure gauge. I also ran a temporary line between the gauge and the tank thinking maybe there was a leak in the line but it’s just the same. I’ve also capped off the tank from the rest of the system using a black plug just after the valve block and seeing the same effect - air leak leaking, so I don’t think it’s the tank and it’s plumbing, it’s somewhere in the valve block. Should also note that watching the gauge the leak is there whether the engine runs or not.

With no bubbles appearing anywhere I’m at a loss and don’t really want to pull the valve block apart again but not know where is “bad” nor do I want to chop up my EAS adding in manual valves etc. in my mind this opens more problems further down the road. So going back to my original question - in this scenario would UV dye in the EAS work? Thanks!

You don't want any liquid of any kind in the eas system.

is the tank rusty? it is possible to be porous

8v_chris said:

I’m sure this has been flogged to death and then some but I didn’t find a response to a similar question online and I’m pretty much just rambling out loud here but hopefully the huge knowledge base here will know. Can a leak on the EAS be detected using a UV type dye similar/the same as used on an AC system to nail down a leak? I’ve had a slow leak on my EAS for a wee while now and it needs addressed so as not to burn out my pump.

The situation - my EAS inflates as normal, works as normal (ignoring a recent pump failure prior to valve block rebuild), goes from empty tank to full tank in about 8-9 minutes or so with the door open etc, and crucially, the air bags do not lose any air at all overnight; no low corners indicating a bad bag and she will sit up nice and high for days on end with no problems. The tank however will have emptied itself to about 20 psi over say two days. This morning it was full at 130 psi and over 4 hours dropped to 90 psi. I’m monitoring this on my inline pressure gauge plumbed in on line 6 between the level block and the tank.

What I’ve tried - I found that about a few weeks ago my diaphragm valve in the valve block was leaking and air was moving back through valve block, through the air dryer and out into the air. This was found by the bubble mixture method. I’ve stripped the block down and did a full rebuild from X8R, using the Vaseline in the right places and it sealed it up nicely. I’ve been round and round the while system with more bubble mixture but haven’t found anything since despite this weep of air showing on my air pressure gauge. I also ran a temporary line between the gauge and the tank thinking maybe there was a leak in the line but it’s just the same. I’ve also capped off the tank from the rest of the system using a black plug just after the valve block and seeing the same effect - air leak leaking, so I don’t think it’s the tank and it’s plumbing, it’s somewhere in the valve block. Should also note that watching the gauge the leak is there whether the engine runs or not.

With no bubbles appearing anywhere I’m at a loss and don’t really want to pull the valve block apart again but not know where is “bad” nor do I want to chop up my EAS adding in manual valves etc. in my mind this opens more problems further down the road. So going back to my original question - in this scenario would UV dye in the EAS work? Thanks!

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No to UV dye and as far as I'm concerned, it's no to Vaseline. Have you checked the dryer for leaks, they rust like the tank.

Datatek said:

No to UV dye and as far as I'm concerned, it's no to Vaseline. Have you checked the dryer for leaks, they rust like the tank.

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Yes, I’ve had the dryer out and apart, replaced all of the o rings and the ballast type stuff in there too. I had the tank out a while ago as it has service rust on it. Took it back to bare metal with a poly carbide disc and coated it with por15. There wasn’t anywhere obvious on it that seemed to be holed or at least corroded enough to have a hole. I’ve also thrown loads of bubble mixture up and around the tank and couldn’t see any bubbles. That aside though, the pressure still drops when the tank was capped off with a blanking push fit plug.

8v_chris said:

Yes, I’ve had the dryer out and apart, replaced all of the o rings and the ballast type stuff in there too. I had the tank out a while ago as it has service rust on it. Took it back to bare metal with a poly carbide disc and coated it with por15. There wasn’t anywhere obvious on it that seemed to be holed or at least corroded enough to have a hole. I’ve also thrown loads of bubble mixture up and around the tank and couldn’t see any bubbles. That aside though, the pressure still drops when the tank was capped off with a blanking push fit plug.

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Where are you measuring pressure when the tank is capped off and where is the cap.
Have you removed the filter/silencer at the rear of the valve block and checked for leaks there?

Datatek said:

Where are you measuring pressure when the tank is capped off and where is the cap.
Have you removed the filter/silencer at the rear of the valve block and checked for leaks there?

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I have a T piece I fitted into line 6 just after the pipe for the tank leaves the valve block. One end runs on to the tank as it should the other to my wee gauge.

When capped off, I just pulled the pipe to the tank out and replaced it with a small length of pipe with the cap in it so the pressure reading is being taken from the valve block to the plug. Hopefully I’ve described that properly!

I’ve had the exhaust silencer off but can’t feel anything, it’s also been sprayed with bubble mixture but no bubbles appear.

8v_chris said:

I have a T piece I fitted into line 6 just after the pipe for the tank leaves the valve block. One end runs on to the tank as it should the other to my wee gauge.

When capped off, I just pulled the pipe to the tank out and replaced it with a small length of pipe with the cap in it so the pressure reading is being taken from the valve block to the plug. Hopefully I’ve described that properly!

I’ve had the exhaust silencer off but can’t feel anything, it’s also been sprayed with bubble mixture but no bubbles appear.

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From your description, it doesn't sound as though you are reading tank pressure but pressure remaining in the system so I must be misreading it.

Soapy water is the best leak finder for EAS. Squirt over every joint, and anywhere else you suspect leaks.

I'm also confused about your tank check. With the system off, the tank pressure should be blocked by NRV-1 from the diaphragm valve & dryer. NRV-2 will be open allowing tank pressure to one side of Inlet valve.

Check for pressure at the dryer port with system off. This will always happen if NRV1 is leaking. Alternatively, it requires both Inlet valve and Exhaust valve to be leaking air.

Inlet & Exhaust valves could also be leaking through the bases. Easy to check by taking the solenoids off & squirting soapy water around the bases while solenoids are off.

Datatek said:

From your description, it doesn't sound as though you are reading tank pressure but pressure remaining in the system so I must be misreading it.

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pwood999 said:

Soapy water is the best leak finder for EAS. Squirt over every joint, and anywhere else you suspect leaks.

I'm also confused about your tank check. With the system off, the tank pressure should be blocked by NRV-1 from the diaphragm valve & dryer. NRV-2 will be open allowing tank pressure to one side of Inlet valve.

Check for pressure at the dryer port with system off. This will always happen if NRV1 is leaking. Alternatively, it requires both Inlet valve and Exhaust valve to be leaking air.

Inlet & Exhaust valves could also be leaking through the bases. Easy to check by taking the solenoids off & squirting soapy water around the bases while solenoids are off.



View attachment 300839

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Sorry for the confusion, I’m either not explaining it well or I’ve fitted it incorrectly. I’ve attached a photo. You can see line 6 with a T piece running to the tank, the upright connector runs to my gauge. When I pulled the right pipe that runs to the tank and replaced it with the cap to block the pipe (where my finger is) it’s measuring the air left in the system, not the tank as it’s now open to the atmosphere as unplugged. When I had the tank blocked off and the pipe cap on the compressor ran very briefly, got to pressure and then pressure began to drop as soon as it knocked off.

The valve block does not retain much air when off - i.e. just the main gallery as I described above. It could also be the gauge leaking internally - many cheap gauges do leak. (I have several !! )

Go back to basics. Reconnect the tank line normally & pressurise it. Then check all joints for leaks with soapy water.

pwood999 said:

The valve block does not retain much air when off - i.e. just the main gallery as I described above. It could also be the gauge leaking internally - many cheap gauges do leak. (I have several !! )

Go back to basics. Reconnect the tank line normally & pressurise it. Then check all joints for leaks with soapy water.

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I was doing this again this afternoon but can’t find anything. I’m thinking it must be a leak at the valve block but it’s either on the underside where I can’t see when it’s all in place or else it’s internal somewhere which is where I thought I had a good idea with the UV dye but it seems not. Really thought I was onto something there!! There’s no air bubbles around the base of the inlet or exhaust valve on top, so I guess they’re good in that respect?

I had wondered about the gauge but thought I’d bought a decent one. Short of trying a different one I’ve no way to test it.

When your talking about pressure in the dryer port how much is too much, or should there be nine at all ordinarily? I thought that the dryer wouldn’t retain any as it’s either heading to the tank or straight out through the exhaust?

You do realise that the system is expected to lose pressure, RAVE if I remember correctly specifies a drop over night of around 5/10mm as being acceptable.
I have never found the need to use gauges, if the system works, does not drop excessively and the compressor doesn't run too much then all is well.

Datatek said:

You do realise that the system is expected to lose pressure, RAVE if I remember correctly specifies a drop over night of around 5/10mm as being acceptable.
I have never found the need to use gauges, if the system works, does not drop excessively and the compressor doesn't run too much then all is well.

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Yeah I understand it will lose a bit of pressure but surely the tank shouldn’t empty itself overnight? I’m not seeing any drop in height, or nothing noticeable, it’s a loss of tank pressure I’m seeing.

8v_chris said:

I’m sure this has been flogged to death and then some but I didn’t find a response to a similar question online and I’m pretty much just rambling out loud here but hopefully the huge knowledge base here will know. Can a leak on the EAS be detected using a UV type dye similar/the same as used on an AC system to nail down a leak? I’ve had a slow leak on my EAS for a wee while now and it needs addressed so as not to burn out my pump.

The situation - my EAS inflates as normal, works as normal (ignoring a recent pump failure prior to valve block rebuild), goes from empty tank to full tank in about 8-9 minutes or so with the door open etc, and crucially, the air bags do not lose any air at all overnight; no low corners indicating a bad bag and she will sit up nice and high for days on end with no problems. The tank however will have emptied itself to about 20 psi over say two days. This morning it was full at 130 psi and over 4 hours dropped to 90 psi. I’m monitoring this on my inline pressure gauge plumbed in on line 6 between the level block and the tank.

What I’ve tried - I found that about a few weeks ago my diaphragm valve in the valve block was leaking and air was moving back through valve block, through the air dryer and out into the air. This was found by the bubble mixture method. I’ve stripped the block down and did a full rebuild from X8R, using the Vaseline in the right places and it sealed it up nicely. I’ve been round and round the while system with more bubble mixture but haven’t found anything since despite this weep of air showing on my air pressure gauge. I also ran a temporary line between the gauge and the tank thinking maybe there was a leak in the line but it’s just the same. I’ve also capped off the tank from the rest of the system using a black plug just after the valve block and seeing the same effect - air leak leaking, so I don’t think it’s the tank and it’s plumbing, it’s somewhere in the valve block. Should also note that watching the gauge the leak is there whether the engine runs or not.

With no bubbles appearing anywhere I’m at a loss and don’t really want to pull the valve block apart again but not know where is “bad” nor do I want to chop up my EAS adding in manual valves etc. in my mind this opens more problems further down the road. So going back to my original question - in this scenario would UV dye in the EAS work? Thanks!

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My guess would be the cones on the solenoids in the valve block. @kurtjohnson10 might be able to help you find a replacement.

Grrrrrr said:

My guess would be the cones on the solenoids in the valve block. @kurtjohnson10 might be able to help you find a replacement.

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On one of the three non return valves? I thought the fines were just there to help the rubber seal seat correctly. The valve block I have is a replacement so I’ve no idea if it’s a high mileage one or not.

Look at the diagram & understand the air flows. There's two easy ways to check for slow internal valve block leaks.

1) Reconnect everything without the gauge or tee pieces & fill the tank. Put a balloon over the exhaust silencer, and wait a few hours. If the balloon inflates then something in the valve block is leaking. (balloon will burst if you run the car with it there !! )

2) As above reconnect everything & fill the tank. Then connect your gauge to the drier using an 8mm to 6mm adapter. Wait a few hours. If the gauge rises then NRV-1 is probably leaking.

pwood999 said:

Look at the diagram & understand the air flows. There's two easy ways to check for slow internal valve block leaks.

1) Reconnect everything without the gauge or tee pieces & fill the tank. Put a balloon over the exhaust silencer, and wait a few hours. If the balloon inflates then something in the valve block is leaking. (balloon will burst if you run the car with it there !! )

2) As above reconnect everything & fill the tank. Then connect your gauge to the drier using an 8mm to 6mm adapter. Wait a few hours. If the gauge rises then NRV-1 is probably leaking.

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I like the balloon idea If you don't have a balloon, a condom will do just as well

Ok I’ll try those and see how I get on, thanks for your patience!

I have an as new valve block for sale and a brand new compressor for sale if needed. valve block is as new .