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NewellCrazy · 04-01-2013, 11:43 PM

Here is the information Gordon is referring to.

It bugs me that the leveling valves seem to be a chronic problem, and there is not a good way to diagnose which one is giving you the problem.

So, I made a little jig to test the valves with. It was pretty simple, although the threads on the valves are 1/2-20 that is really close to 1/4 NPT, so I cheated and used a 1/4 NPT pipe coupling. On the side that mates to the valve, I used a brass washer robbed from an old valve, and used epoxy to seal the 1/4 NPT coupling to the washer. I drilled a hole in the washer to simulate the setup on the manifold distribution block in the coach. so to use the jig I applied air through a regulator, and put a soap bubble over the hole in the washer. I increased the air pressure using the regulator until I saw a bubble form. I called that the leak pressure.

I conducted a little experiment with the help of another. I was sent two old KIP valves that he had, I had two old AV brand valves, and two brand new HWH valves I just bought. My goal was to determine the cause of the chronic failures.

I disassembled all three sets and took some measurements of the springs and valve seats. I also used the jig to determine the pressure at which the valves started to leak by. To be more accurate, I should have used a 12 VDC source and cycled the valves a few times. Maybe next time.

Here are the data:
New/Used Brand Spring Ht Durometer Leak Pressure
New HWH (AV) 0.52 47 100+
New HWH (AV) 0.54 50 100+
Used AV 0.47 49 55
Used Kipp 0.54 35 10
Used Kipp 0.56 34 10

AV Urethane seat 100+
Reworked seat, lapped 70
New valve old seat 70
Old valve, new seat 100+

The experiment seems to indicate that significant deterioration in performance. No wonder we can't keep air in the bus. You can also see that the hardness of the seat, and spring height does not explain the change in leakage. I concluded it had to be degradation of the contact between the valve seat and the valve body.

I had made a new seat for one of the old valves out of same cast-able urethane I had in the office. First indication is that something like that may work to refurbish the valves, since that reworked valve did achieve near new leak rates. I do not know how long that material would hold up under use

I also tried lapping the valve and valve seat together using finger pressure and a light lapping compound (toot-paste). The lapping raised the leak pressure 15 pounds but did not fix the leak.

I also swapped an used seat into a new body, and a new seat into an old body to determine if the leak was seat or body related. One single data point indicates it's the seat.

It makes sense that the seat would be degraded by air blowing past it. The valve body is brass and the seat seems to be some moderately hard polymer. That was my initial thoughts anyway, but I had to prove it to myself before going to the next step.

I had two goals. One to make a device to be able to test the valves easily. Mission accomplished. Total cost about two dollars. The second was to ultimately be able to recondition the valves to seal in an easy and inexpensive manner. I will have to get some different urethane's to try now. I'll report back later on what I find.

Of course if the valve is not opening, that's a different problem, and requires a new coil. But generally people complain about them leaking.

Guys, don't throw the old ones away, there may be help on the horizon.

Just wanted to update you on the little jig I made. I used it today to test all 12 leveling valves on the coach. Four would not hold 100 lbs pressure without leaking.

It took about 1.5 hours to test them all. I marked the solenoid coils on all with the correct position, and then I unscrewed the nut that holds the coil on. I did that instead of unhooking the wiring. After that it's a quick job to unscrew the valve body and screw them onto the jig. Since I knew the new ones will hold at 100 lbs, I set the regulator on my air compressor at a 100 and just popped the jig on and off with a quick disconnect.

I had two new ones, so I had to try something on the other two that were leaking. I stole the idea of putting in a piece of material from HoosierDaddy. I used a pick to dig out the old seal material and used a piece of hard rubber to replace what I dug out. Actually I cut up a squeegee that I had in the shop. It was the right thickness, and seemed about the right hardness. I used a little silicone adhesive to seal it in the cavity. I tested the "fixed" valves and they held 100 psi, so I put them in. We'll see how they hold up with time. I know which ones they are so they'll be easy to check.

I have been looking at the old valves with a microscope to see what was going on. All of the failed ones have microscopic cracks around the sealing area. The new ones are perfectly smooth.

If the fix holds up over time, then it will be an incredibly inexpensive solution compared to replacing valves at 80 per shot and hoping you got the right one.

On yeah, one more thing the valves that were bad must have been the ones that came with the coach, there was a 04 93 code on the valve body.

After several attempts with so so results, I am pretty confident that I have found a way to repair the leaking valves. If the valve isn't opening, that's another issue.

The repair involves removing the solenoid, then removing the center piece that is inside the solenoid. When you open that up, you will find a spring and a steel core. In the bottom of that core you will see the valve seal. Mine have been black, green, and blue depending on who made the valve.

I take a steel pick and remove the first 1/4 inch of the old seal. I have two solutions that work equally well. One is more time consuming than the other. The first is I have used Permatex High Torque RTV sealant to make a squirt into the cavity where I just removed the seal. I leave it quite proud (sticking up above the surface) and after it cures I put it on the belt sander and ground it flat. It seals like a charm. The Permatex High Torque is available at most auto parts places. Other RTV's do not cure as hard as this one. Remember I tested the durometer on the original valves and this particular brand and grade replicates the original seal. A tube of it will probably fix three or four hundred valves. HOWEVER, there is one HUGE problem with this approach. It takes about two weeks for the RTV to completely cure. If you try to put it back in before then, the seal will deform and fail. I tested this, take my word.

The second solution was to use a two part cast-able urethane. I obtained such a material from McMaster Carr http://www.mcmaster.com/#urethane-ca...mpounds/=gm3q3 in 60D durometer. The closest they had to the original hardness. You have to be very precise on your mixing ratios, because the ratio determines the final hardness, but other than the measuring this technique is much easier. Dig out 1/4 inch of the old seal, mix urethane, drizzle just enough into the cavity that the surface forms a little bulge above flat. Let cure for 24 hours. No post sanding or flattening required.

Cost of the urethane is about $35.00. It would probably do a 1000 or more valves in the smallest quantity they sell.

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04-01-2013, 11:43 PM	#3
NewellCrazy Senior Member Join Date: Sep 2006 Location: Sugarland, TX or Salida,CO Posts: 1,867	Here is the information Gordon is referring to. It bugs me that the leveling valves seem to be a chronic problem, and there is not a good way to diagnose which one is giving you the problem. So, I made a little jig to test the valves with. It was pretty simple, although the threads on the valves are 1/2-20 that is really close to 1/4 NPT, so I cheated and used a 1/4 NPT pipe coupling. On the side that mates to the valve, I used a brass washer robbed from an old valve, and used epoxy to seal the 1/4 NPT coupling to the washer. I drilled a hole in the washer to simulate the setup on the manifold distribution block in the coach. so to use the jig I applied air through a regulator, and put a soap bubble over the hole in the washer. I increased the air pressure using the regulator until I saw a bubble form. I called that the leak pressure. I conducted a little experiment with the help of another. I was sent two old KIP valves that he had, I had two old AV brand valves, and two brand new HWH valves I just bought. My goal was to determine the cause of the chronic failures. I disassembled all three sets and took some measurements of the springs and valve seats. I also used the jig to determine the pressure at which the valves started to leak by. To be more accurate, I should have used a 12 VDC source and cycled the valves a few times. Maybe next time. Here are the data: New/Used Brand Spring Ht Durometer Leak Pressure New HWH (AV) 0.52 47 100+ New HWH (AV) 0.54 50 100+ Used AV 0.47 49 55 Used Kipp 0.54 35 10 Used Kipp 0.56 34 10 AV Urethane seat 100+ Reworked seat, lapped 70 New valve old seat 70 Old valve, new seat 100+ The experiment seems to indicate that significant deterioration in performance. No wonder we can't keep air in the bus. You can also see that the hardness of the seat, and spring height does not explain the change in leakage. I concluded it had to be degradation of the contact between the valve seat and the valve body. I had made a new seat for one of the old valves out of same cast-able urethane I had in the office. First indication is that something like that may work to refurbish the valves, since that reworked valve did achieve near new leak rates. I do not know how long that material would hold up under use I also tried lapping the valve and valve seat together using finger pressure and a light lapping compound (toot-paste). The lapping raised the leak pressure 15 pounds but did not fix the leak. I also swapped an used seat into a new body, and a new seat into an old body to determine if the leak was seat or body related. One single data point indicates it's the seat. It makes sense that the seat would be degraded by air blowing past it. The valve body is brass and the seat seems to be some moderately hard polymer. That was my initial thoughts anyway, but I had to prove it to myself before going to the next step. I had two goals. One to make a device to be able to test the valves easily. Mission accomplished. Total cost about two dollars. The second was to ultimately be able to recondition the valves to seal in an easy and inexpensive manner. I will have to get some different urethane's to try now. I'll report back later on what I find. Of course if the valve is not opening, that's a different problem, and requires a new coil. But generally people complain about them leaking. Guys, don't throw the old ones away, there may be help on the horizon. Just wanted to update you on the little jig I made. I used it today to test all 12 leveling valves on the coach. Four would not hold 100 lbs pressure without leaking. It took about 1.5 hours to test them all. I marked the solenoid coils on all with the correct position, and then I unscrewed the nut that holds the coil on. I did that instead of unhooking the wiring. After that it's a quick job to unscrew the valve body and screw them onto the jig. Since I knew the new ones will hold at 100 lbs, I set the regulator on my air compressor at a 100 and just popped the jig on and off with a quick disconnect. I had two new ones, so I had to try something on the other two that were leaking. I stole the idea of putting in a piece of material from HoosierDaddy. I used a pick to dig out the old seal material and used a piece of hard rubber to replace what I dug out. Actually I cut up a squeegee that I had in the shop. It was the right thickness, and seemed about the right hardness. I used a little silicone adhesive to seal it in the cavity. I tested the "fixed" valves and they held 100 psi, so I put them in. We'll see how they hold up with time. I know which ones they are so they'll be easy to check. I have been looking at the old valves with a microscope to see what was going on. All of the failed ones have microscopic cracks around the sealing area. The new ones are perfectly smooth. If the fix holds up over time, then it will be an incredibly inexpensive solution compared to replacing valves at 80 per shot and hoping you got the right one. On yeah, one more thing the valves that were bad must have been the ones that came with the coach, there was a 04 93 code on the valve body. After several attempts with so so results, I am pretty confident that I have found a way to repair the leaking valves. If the valve isn't opening, that's another issue. The repair involves removing the solenoid, then removing the center piece that is inside the solenoid. When you open that up, you will find a spring and a steel core. In the bottom of that core you will see the valve seal. Mine have been black, green, and blue depending on who made the valve. I take a steel pick and remove the first 1/4 inch of the old seal. I have two solutions that work equally well. One is more time consuming than the other. The first is I have used Permatex High Torque RTV sealant to make a squirt into the cavity where I just removed the seal. I leave it quite proud (sticking up above the surface) and after it cures I put it on the belt sander and ground it flat. It seals like a charm. The Permatex High Torque is available at most auto parts places. Other RTV's do not cure as hard as this one. Remember I tested the durometer on the original valves and this particular brand and grade replicates the original seal. A tube of it will probably fix three or four hundred valves. HOWEVER, there is one HUGE problem with this approach. It takes about two weeks for the RTV to completely cure. If you try to put it back in before then, the seal will deform and fail. I tested this, take my word. The second solution was to use a two part cast-able urethane. I obtained such a material from McMaster Carr http://www.mcmaster.com/#urethane-ca...mpounds/=gm3q3 in 60D durometer. The closest they had to the original hardness. You have to be very precise on your mixing ratios, because the ratio determines the final hardness, but other than the measuring this technique is much easier. Dig out 1/4 inch of the old seal, mix urethane, drizzle just enough into the cavity that the surface forms a little bulge above flat. Let cure for 24 hours. No post sanding or flattening required. Cost of the urethane is about $35.00. It would probably do a 1000 or more valves in the smallest quantity they sell. [ATTACH][/ATTACH][ATTACH][/ATTACH][ATTACH][/ATTACH] __________________ Sean If Ain't a Newell, It Ain't Wurt Oonin!