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Help with Air Tanks and leaks


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Earlier this summer I had checked my air systems over pretty good and did not find any problems. 

Fast forward to now, I am on a trip.  I noticed a couple days ago that over night when I was ready to leak and turned the key my low air alarm came on.  In the past I could go days without the tanks leaking down.  So today I crawled under the coach and started to spray down fittings.  On both the front and the rear tanks there are (I believe) pressure protection valves that supply air to air leveling, I have a air schematic for a 1999 Windsor and it shows it as n15759dc  and a search gets me this   https://www.anythingtruck.com/product/070-KN31000.html.  There are two on the rear tank and two on the front tank.  All 4 are leaking air, and it looks like where the two parts are attached together with screws. Hers a picture of the front two, as you can see leaking pretty bad.   I'm going to ask the question, is this suppose to be that way, is this how they relieve pressure. 

Air pressure stays up while traveling.

The schematics that I have do not explain how these pressure protection valves work, the couple websites I went to did not provide explanation.  Can someone take a shot on it in layman's terms.  The air bags seem to stay up, I've boon docked 3 or 4 nights with the jacks up and the coach has stayed level. 

I am in a remote area right now and would not attempt to fool with these now.   I could not find any other leaks. 

Should I be concerned. 

 

 

 

Air Valve Leak.jpg

Edited by jacwjames
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I had a reply from CountyB on the IRV2 forum.  He as an endless supply of documents and provided me with the following.  The valves are designed to leak within a set pressure and where I saw mine leaking was at the exhaust vent.  I believe all the valves that were leaking were in the air leveling circuit and since I had aired up and then used the jacks to lift he coach they may have been exhausting because of that.  The air bags have to exhaust from some where and it seems like a likely place. 

I am going to do some more digging though as to why my system looses air faster then before. 

Bendix PR-4 pressure protection valve.pdf

Also, I just checked my air pressure gauge and it has not lost pressure in the last 4 hours. 

I checked the front Pressure Protection Valves, since I could spray them down by reaching over the tire, and they are not leaking now. 

 

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Jim,  first let me say I'm not an expert on anything, but I believe you are on the wrong track concerning PPVs ( pressure protection valves ).

PPVs on my Windsor have no vent.  What they do is allow air through to the suspension etc. until the pressure drops for some reason below it's preset pressure then it stops that flow to protect the brake system.  Mine leaked at the gaskets like yours.   They were pretty easy to replace except the ones that had some extra ports.  They showed the threaded ports on line but they were not threaded when I received them.  I finally had to find that particular one locally.

Edited by Ray Davis
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I've already decided these aren't an issue. 

I will do a brake leak down test tomorrow but I think I'm over reacting.  

I guess I'm getting old and paranoid. 

Just think how many people drive these rigs without any knowledge or concern, just get in and drive.  I've spent 100's of hours working on my rig this year.   Two days before I left on this trip I did a complete lube and inspection of the undercarriage. I believe it's in pretty good mechanical condition.  But if your not smart enough to have some concerns you probably shouldn't be driving one of these beasts. 

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1 hour ago, Jdw12345 said:

What exactly is a “Brake Leak Down Test”?

Test air leakage rate: With a fully-charged air system (typically 125 psi), turn off the engine, release the service brake, and time the air pressure drop. The loss rate should be less than 2 psi in 1 minute for single vehicles and less than 3 psi in 1 minute for combination vehicles.

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41 minutes ago, Jdw12345 said:

I see, I misunderstood what the op was looking for, I thought he said he had air leaks while the coach was parked not rolling down the road. 

If you have air leaks parked you probably have air leaks rolling down the road, just depends on how bad and whether the air system can keep up.

 

 

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I did a brake air test this morning, I charged the system and then held the brake pedal down for 3 minutes had the air guage did not move at all.  Did it again for 1 minute with the same results so I'm good there.  Also tested the park brake, charged the air system, released the brake, turn key off and watched the air pressure gauge, it did not move after 1 minute.

I have been doing some more research and my version of the PPV should not be leaking.  Not sure why/how all 4 started to leak at the same time just seems odd.

Any opinions on if this is a immediate fix situation.

Now I'm not sure whether I should pack it up and home and fix (only ~1500 miles away). 

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So your air brakes work per DOT test, your air leveling holds air, seems your only concern is that the tanks leak down over a night or two? That would not stop me at all. For today's cost of driving 1500 miles home you can as well have a truck shop replace the leaky valves on your way if you have no resources to do it yourself. An overnight leak down of the tanks would not concern me that much at all. Since your multiple valves started leaking at the same time, I would check for water/sludge in tanks, then the drier.

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3 hours ago, Flyinhy said:

Test air leakage rate: With a fully-charged air system (typically 125 psi), turn off the engine, release the service brake, and time the air pressure drop. The loss rate should be less than 2 psi in 1 minute for single vehicles and less than 3 psi in 1 minute for combination vehicles.

Always wondered if you would actually be able to see a 2 or 3psi drop with these little 0-150psi gauges 🔍.

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Jim, when I was working on my air leaks, I ended up replacing all four of those valves.  Being 20 years old (the coach) and not being that expensive I replaced them for peace of mind.  Pray safe travel for you and yours. God Bless, Ed & Sylvia

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23 hours ago, jacwjames said:

There are two on the rear tank and two on the front tank.  All 4 are leaking air,

James.....that part looks serviceable. I'm not familiar with that particular valve but it looks similar to a QR-1 valve and those only have an o-ring and a flat disc with a spring. Any small piece of dirt will not allow the disc to seal and cause a slight leak.

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3 hours ago, Ivan K said:

So your air brakes work per DOT test, your air leveling holds air, seems your only concern is that the tanks leak down over a night or two? That would not stop me at all. For today's cost of driving 1500 miles home you can as well have a truck shop replace the leaky valves on your way if you have no resources to do it yourself. An overnight leak down of the tanks would not concern me that much at all. Since your multiple valves started leaking at the same time, I would check for water/sludge in tanks, then the drier.

I just changed the air dryer cartridge ~4 months ago and checked my tanks when I did my last lube jog this month.  No sign of condensation.

One big difference is that the coach has sat for extended periods of time over the last 4 years. 

Earlier this year I had been reading about leak down etc so for the heck of it I started the coach and parked it and it took +4 days for the air tanks to bleed down.  The air bags don't leak down at all, they'll stay up for +1 week easy.  Only reason why I started to investigate was that after a night boon docking, when I went to start the coach the low air alarm went off, that's why I started checking.

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4 hours ago, 96 EVO said:

Always wondered if you would actually be able to see a 2 or 3psi drop with these little 0-150psi gauges 🔍.

Hum, lets see if I wait 15 min instead of 1 min then look for less than 30 psi drop I probably could see that.

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5 hours ago, jacwjames said:

Any opinions on if this is a immediate fix situation.

Now I'm not sure whether I should pack it up and home and fix (only ~1500 miles away). 

I wouldn't call off my trip over leaking PPVs,  not unless you are having difficulties maintaining pressure, and I think you said earlier that maintaining was not a problem.    I bet you can't even hear them leak.    I replaced mine because they bubbled,  but I could not tell any difference except the new ones didn't bubble. 

As I recall I had 3 like this.  eyJ3aWR0aCI6NDM1LCJoZWlnaHQiOjQzNSwiZml0IjoiY29udGFpbiIsIndhdGVybWFya2VkIjp0cnVlLCJrZXkiOiJhc3NldHMvaW1hZ2VzLzI1OTI5MTAvcHJvZHVjdC83ZWZmODE2Y2Q3OWRiY2IzYzE1MTIzMzdmZTM1Zjc0MS5qcGciLCJ2ZXJzaW9uIjoyfQ==.jpg?s=3460df4f7fdd409116c0d1e2482142dfcc059165b91663c4ad42a11d8f32bea8

and 1 like this    eyJ3aWR0aCI6NDM1LCJoZWlnaHQiOjQzNSwiZml0IjoiY29udGFpbiIsIndhdGVybWFya2VkIjp0cnVlLCJrZXkiOiJhc3NldHMvaW1hZ2VzLzg2MjM5MTYvcHJvZHVjdC80MTgwODhjMTk3NWFlMzMyY2M3MmQ3OTdkZWY1ODgwNC5qcGciLCJ2ZXJzaW9uIjoyfQ==.jpg?s=b6f5777ee81562f2b6f76d57fafbaefa6fa500d85a9d4c4e55a8b0b64e9fc846 When it arrived those ports on top were not drilled out or threaded                          This type is not as common as the other 3.   I finally found one at a truck parts about 40 mi from me.

 

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When I was under the coach just before I left I did not hear any leaks.  Where I am parked now there is a transformer station ~100 yards away which loud, I can't hear air leaks over that. 

Just checked my air pressure and it has not dropped since I tested the brakes this AM.  Maybe I'm hallucinating.

 

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Replaced all my pressure protection valves got them from advanced auto they sell World American brand (American made) well known in the trucking industry for $15 at that price makes no sense to try to fix the gasket. WAKN31000 was a exact replacement for me.

Roy 2003 Dynasty

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So I cut my trip short and headed home. 

One issue was that the rate of air loss was all over the place.  Most times it would be overnight  but one time I stopped and when I started the rig ~30 minutes later the low air alarm went off.   There was only one time that I heard one of the PPV's leaking air and then closing.   While driving I would always maintain between 100-120 psi.  

In AZ I spent about an hour trying to find a shop, good luck with that especially on a Thanksgiving weekend.  My gut feeling was to high tail it home so that's what I did. 

Left Holbrook AZ about 11AM Saturday and got home today to E TN.    I did take the time to stop at the Hot Springs National Park in AR just to say I've been there. 

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