Leaking Non Return Valves in the Valve Block

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mcapinha

mcapinha

Active Member
Posts
549
Location
Portugal
Hi all!

I've come to the conclusion that I have at least one bad Non Return Valve: after replacing all the o-rings in the valve block I noticed that the Rangie was performing it's little dance, with the front springs. RR.net suggests this is a bad valve that allows some pressure into the front springs that ends up being released if the front gets too high.
So, i took out the block and the valves seemed ok. Gave them a good cleaning and was extra carefull installing the top of the block, to prevent any problems. But now I have a constant leak from the air silencer :doh:
Any ideas on how I can be sure that the valve is shagged ? Visual inspection revelead no problems.

Thanks :)
 
Hi JT,
I'll share everything I learn :)

Took out the block, rotated the valves and still no joy. It is still leaking from the silencer whenever the compressor is off. If the compressor is on it does not leak (if it did, it would indicate that the diaphragm was shot).

Can someone verify my findings about the correspondence between the Non Return Valves {1,2,3} as indicated by RAVE and the actual paths in the block ?
dsc06614copy.jpg



Also, here's a picture of my NRVs. They don't look to bad to me..
dsc06615copy.jpg


Thanks :)
 
mcapinha said:
Hi JT,
I'll share everything I learn :)

Took out the block, rotated the valves and still no joy. It is still leaking from the silencer whenever the compressor is off. If the compressor is on it does not leak (if it did, it would indicate that the diaphragm was shot).

Can someone verify my findings about the correspondence between the Non Return Valves {1,2,3} as indicated by RAVE and the actual paths in the block ?
dsc06614copy.jpg



Also, here's a picture of my NRVs. They don't look to bad to me..
dsc06615copy.jpg


Thanks :)
Click to expand...

From what i can see these valves look ok. But have a close look and file (with a very fine file) any lip on the conical guide tips that could snag and cause the valve not to seat squarely. You will have a couple of selonoid valves (the inlet and exhaust) with a different type of seal on them than the valves for the airbags. Instead of having an external spring they have a spring in the end of the selonoid piston. Stretch this spring about 2.5 to 3 mm to increase the pressure on the seal which over time develops a depression in the rubber seal end. Also if you have fitted the modified diapragm valve from the Dutch company, it is much stiffer than the OEM valve and sometimes needs more spring pressure to get it to seal properly, stretch the spring for this by 2.5 to 3 mm also.
 
Thanks for the great input (as always), Wammers.

Probably won't have a chance to get the block out (for the 6th time) until the weekend, but I'll let you know how it went.
Is it a straightforward job to get the springs out of the inlet and exhaust solenoids? I didn't notice that they were "serviceable" when I changed the o-rings :confused:
 
mcapinha said:
Thanks for the great input (as always), Wammers.

Probably won't have a chance to get the block out (for the 6th time) until the weekend, but I'll let you know how it went.
Is it a straightforward job to get the springs out of the inlet and exhaust solenoids? I didn't notice that they were "serviceable" when I changed the o-rings :confused:
Click to expand...

Surely you changed the O rings on the solenoid valves. When you remove the coils to remove the valves themselves you have four screws under each one. Two to hold it in position and two phillips to hold valve together. Remove the valve then the phillips screws and pull the valves apart you will find a piston and a spring. On the four corner valves the springs are on the outside of the piston on the inlet and exhaust they are in the end of the pistons. Or at least they are on mine. They are a much weaker spring and if the rubber seal has a depression in it from use the spring pressure is reduced so i stretched mine about 3 mm all is now well.
 
Yup, did all the o-rings in every valve.
I did undo the philips screws on one of them but nothing came apart, and to be honest, was not very willing to break one of them :) Will be more persistent this time.
 
mcapinha said:
Yup, did all the o-rings in every valve.
I did undo the philips screws on one of them but nothing came apart, and to be honest, was not very willing to break one of them :) Will be more persistent this time.
Click to expand...


Looking at the valve block from the driver side there are five valves on top and two on bottom. The first one on the left is the inlet valve the next two and the two below them are the four corner valves. The forth valve is the outlet valve the fifth one above the diaphragm block is the exhaust valve. The exhaust valve only operates to unload the compressor when it stops, this air is blown backwards through the airdrier to dry any moisture out of it and send it to atmosphere. Only the other six valves operate the EAS. For the suspension to rise the inlet valve and any of the four corner valves must be open. For the suspension to go down the outlet valve and any of the four corner valves must be open. If you have a constant leak from the exhaust port and none of the corners is deflating then it must be leaking from the tank circuit. If you have a constant leak from the exhaust port and one corner is dropping then you have a leak on that corners dedicated valve and the outlet valve. It is a question of tracing the leak through the various valves. Trial and error i am afraid.
 
Well, I'm out of ideas:
Assembled the block in the workbench and with some 6mm and 8mm piping I connected it in a way that I could test it's operation. Setup a pressure gauge in the tank port and manually ran the compressor (powered by a PC PSU). I got only get to 6bar, because my PSU only delivered 10A and the compressor seems to require around 20. No leaks, pressure stayed constant, so moved the valve block into the RR.
All was well with no leaks from the exhaust, as I stopped the compressor a few times to check this. As soon as it hit 10bar, the compressor stopped (pressure switch) and the leak revealed itself once more :(
With the VB in place, disassembled the first (looking from front of car) and 2nd valves (inlet and exhaust) and the last one (diaphragm). Disassembled the inlet and exhaust solenoids and switched the plungers (also lengthened the spring by 3mm, as Wammers suggested). Once reassembled, it ran fine for a while, did some short trips, but after a longer trip, had the exhaust leak again :(
Since messing with the 3 solenoids seemed to have helped, I'm guessing the Non Return Valves are fine...

Help ? :)
 
mcapinha said:
Well, I'm out of ideas:
Assembled the block in the workbench and with some 6mm and 8mm piping I connected it in a way that I could test it's operation. Setup a pressure gauge in the tank port and manually ran the compressor (powered by a PC PSU). I got only get to 6bar, because my PSU only delivered 10A and the compressor seems to require around 20. No leaks, pressure stayed constant, so moved the valve block into the RR.
All was well with no leaks from the exhaust, as I stopped the compressor a few times to check this. As soon as it hit 10bar, the compressor stopped (pressure switch) and the leak revealed itself once more :(
With the VB in place, disassembled the first (looking from front of car) and 2nd valves (inlet and exhaust) and the last one (diaphragm). Disassembled the inlet and exhaust solenoids and switched the plungers (also lengthened the spring by 3mm, as Wammers suggested). Once reassembled, it ran fine for a while, did some short trips, but after a longer trip, had the exhaust leak again :(
Since messing with the 3 solenoids seemed to have helped, I'm guessing the Non Return Valves are fine...

Help ? :)
Click to expand...

Looking from front of car, first valve on top is inlet, fourth valve is outlet fifth one is exhaust. The second and third from front of car on top and the two directly below them are the four corner valves.
 
wammers said:
Looking from front of car, first valve on top is inlet, fourth valve is outlet fifth one is exhaust. The second and third from front of car on top and the two directly below them are the four corner valves.
Click to expand...

In mine (LHD), counting from the front of the car (the grille), the 3rd and 4th valves are the ones for the airbags: they are directly above the only two in the bottom of block, and aligned with the air hoses for the bags:
copyofimg2232.jpg

(image stolen from the interwebs)
 
mcapinha said:
In mine (LHD), counting from the front of the car (the grille), the 3rd and 4th valves are the ones for the airbags: they are directly above the only two in the bottom of block, and aligned with the air hoses for the bags:
copyofimg2232.jpg

(image stolen from the interwebs)
Click to expand...

That is of course correct talking from memory through a haze of JD fumes is never a good way to describe anything.:confused::confused::confused:
 
Last edited:
To wrap this up, as it may help others, I'm re-posting what I wrote at another forum:

Replaced the 3 o-rings in the NRVs with standard ones (black) but it did not fix my problem.
So, I went back to the drawing table: with the tank full I removed the first valve (exhaust) to find it pressurized. This should not happen as the inlet valve is closed and no air should pass through. I then removed the inlet valve (which resulted in an empty tank) and found that the smaller, inner o-ring was bent out of shape. So I installed one of the older o-rings in the inlet valve and.. the leak went away!

Now, there's one thing that I didn't check for: the presence of air in the exhaust valve could (also) be caused by a leaking valve from the airbags. To be 100% sure that this was a leaking inlet valve, I should have depressurized the springs also.

And now, I need to get a new compressor, because mine is shagged Rebuilt the piston and it still takes around 20minutes to reach 10 bar in the tank :(
 
mcapinha said:
To wrap this up, as it may help others, I'm re-posting what I wrote at another forum:

Replaced the 3 o-rings in the NRVs with standard ones (black) but it did not fix my problem.
So, I went back to the drawing table: with the tank full I removed the first valve (exhaust) to find it pressurized. This should not happen as the inlet valve is closed and no air should pass through. I then removed the inlet valve (which resulted in an empty tank) and found that the smaller, inner o-ring was bent out of shape. So I installed one of the older o-rings in the inlet valve and.. the leak went away!

Now, there's one thing that I didn't check for: the presence of air in the exhaust valve could (also) be caused by a leaking valve from the airbags. To be 100% sure that this was a leaking inlet valve, I should have depressurized the springs also.

And now, I need to get a new compressor, because mine is shagged Rebuilt the piston and it still takes around 20minutes to reach 10 bar in the tank :(
Click to expand...

Did you set the valves in the head correctly? Inlet blade should be totally flat and sit flat on head, blade above it should NOT hold it down it is not for that purpose it is there to prevent excess flexing and should be set with it nose a few thou (15 or so) above main blade. Exhaust valve blade should be totally flat, the anti flex blade above it should be bent back slightly so it does not hold exhaust valve onto seal. Air pressure alone opens and closes the valves. The other blades are just there as support to prevent too large a movement as air is pumped. I have seen these pumps with an O ring fitted in the groove in the piston seal retainer, this causes the seal to round and not seal properly remove it if fitted. Spread seal carefully and refit cylinder.
 
The valves were OK, disassembled them this morning, gave them a cleaning and installed them correctly (took my time to figure out how their were supposed to work and you've just confirmed my conclusions).
It is worth a shot to get a new o-ring for the cylinder, it should be pretty common. What's that seal product that you were suggesting ?
 
mcapinha said:
The valves were OK, disassembled them this morning, gave them a cleaning and installed them correctly (took my time to figure out how their were supposed to work and you've just confirmed my conclusions).
It is worth a shot to get a new o-ring for the cylinder, it should be pretty common. What's that seal product that you were suggesting ?
Click to expand...

What was that. I have just fitted piston seal and new cylinder from the place in Holland excellent up to now. How did you rebuild the piston?
 
mcapinha said:
Lol, something got lost in the translation :)

I also used the kit from the Dutch guys (Range Rover P38 EAS Pump Compressor SEAL + RING / LINER on eBay (end time 25-Oct-10 11:43:07 BST)). It didn't come with a new o-ring and I (mis)understood that you where suggesting some product to form a new seal:
Click to expand...


Ok if you have built the compressor correctly when running it should blow air past your finger over outlet easily. You should not be able to seal it with your finger. If it is not doing this something is wrong with piston seal/valves. It should take with a door open to lock EAS about 6 to 8 mins to fill tank and stop pump, no more. If you have de-pressurised system and leave doors shut it will fill tank and when there is sufficient pressure air bags all at the same time this will take considerably longer than 6 to 8 minutes. What you should be looking at to judge pump efficiency is the time it takes to fill the tank alone with a door open and the EAS disabled.
 
I've lost count to how many times I've depressurized the tank and stood by waiting it to fill up. I have a pressure gauge installed in the line that goes to the tank, so I know what's going on.
It is taking some 20 minutes to get it to 10 bar. Land Rover documents state 7.5, so this is about 3x longer :(
If I put my finger on the outlet, I can seal it for some time. Then pressure builds up and it eventually starts leaking past my finger (not the most scientific test, i know, i know).
 
mcapinha said:
I've lost count to how many times I've depressurized the tank and stood by waiting it to fill up. I have a pressure gauge installed in the line that goes to the tank, so I know what's going on.
It is taking some 20 minutes to get it to 10 bar. Land Rover documents state 7.5, so this is about 3x longer :(
If I put my finger on the outlet, I can seal it for some time. Then pressure builds up and it eventually starts leaking past my finger (not the most scientific test, i know, i know).
Click to expand...

Then your pump is weak it should not be possible to stop the air coming out after a very few seconds. Try it with the inlet filter removed.
 
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