Air Leak

[ziaptrn]

Hello all - I've been following this thread after having had 'air issues' with our rig. In the interest of gathering information to have and/or share in the future - does anyone have a part number for the internal wet/dry check valve located in the front main tank?
I'd like to save it since one never knows!

John

[dandick66]

UPDATE 22 MAY

I installed the new replacement pressure control check valve on Friday 19 May - the first one I received was defective.  I started the engine and the pressure built up to 127 PSI.  The rear tank dropped about 10 PSI, thereby indicating the valve is functioning properly.  I drained the wet tank and both the front and rear tanks held pressure.  I drained the front tank and the rear tank held pressure.  Then I drained the rear tank and the front tank held pressure.  I did restart the engine and let pressures build up between each scenario.  Here is the timeline and pressure readings I recorded.                              
19 May 1430 Front 126/Rear 118 (Following governor cutoff and regeneration).     
19 May 1910 Front 111/Rear 104.  (Approximately 5 hours, 15 PSI drop front, 14 PSI rear)
20 May 0630 Front 91/Rear 91. (Approximately 11 hours, 20 PSI drop front, 13 PSI rear)  
20 May 1900 Front 79/Rear 79.  (Approximately 12 hours 12 PSI drop front, 12 PSI rear)
21 May 0700 Front 67/Rear 67.  (12 hours, 12 PSI drop front, 12 PSI rear)
21 May 1830 Front 59/Rear 59. (Approximately 12 hours, 8 PSI drop front, 8 PSI rear)
22 May 0700 Front 49/Rear 49.  (Approximately 12 hours, 10 PSI front, 10 PSI rear)

I’m not exactly sure what my data indicates.  It appears that the front tank dropped pressure a little faster than the rear until they equalized and then they dropped pressure equally.  It leaks about 1 PSI/hour.  I don’t know the accuracy of the transducer and gauges, but I’m assuming it’s +/- 2 percent.  I have not installed the new spring brake hose yet, but I don’t think that affects any readings since it has no pressure when the parking brakes are engaged.        

 

[96 EVO]

Dan, does your coach have Valid air leveling?

[dandick66]

23 minutes ago, 96 EVO said:

Dan, does your coach have Valid air leveling?

Yes, Vaild leveling system 
VTL01K049

[96 EVO]

Does the compressor run often?

Do you have it disabled, like many of us do when parked long term?

[dandick66]

1 minute ago, 96 EVO said:

Does the compressor run often?

Do you have it disabled, like many of us do when parked long term?

Yes, I have the compressor disabled.  I mounted a switch near the dash and test it periodically.  

[96 EVO]

Ok, you may be losing system air right through that compressor like I was.

Did you see the long thread where Frank removed the head off his compressor and cleaned the reed valve and '0' ring below it?

Worked wonders for me, reducing overnight system air loss!

[dandick66]

 

4 minutes ago, 96 EVO said:

Ok, you may be losing system air right through that compressor like I was.

Did you see the long thread where Frank removed the head off his compressor and cleaned the reed valve and '0' ring below it?

Worked wonders for me, reducing overnight system air loss!

I haven’t seen that thread, but I’ll search for it. 
       
Looking at my air system diagram, the supply to that compressor is only connected to the front tank. Would it cause the rear tank to drop, too?

[96 EVO]

Believe they will equalize.

No guarantee this is where you are losing air, but if your compressor is easy to get to, it's an easy job.

Leave your compressor powered up, and if it starts running frequently, like every few hours, it may be worth doing. 

[dandick66]

1 hour ago, 96 EVO said:

Believe they will equalize.

No guarantee this is where you are losing air, but if your compressor is easy to get to, it's an easy job.

Leave your compressor powered up, and if it starts running frequently, like every few hours, it may be worth doing. 

Ok. The compressor isn’t the easiest thing to get to, but I can access it. I see a .25 inch line running from the front tank to the Valid compressor tank. Out of the compressor, there’s a “T” to the Valid tank and a 3/8 line that runs to the front, rear and tag manifolds.  Could I just plug the .25 and 3/8 lines temporarily and bypass/eliminate the compressor?

[96 EVO]

Should work.

[dandick66]

Ok. I’ll try that a little later today…

1 minute ago, 96 EVO said:

Should work.

 

[96 EVO]

If it's easier, you could just temporarily replace the PPV at your front tank with a plug, and leave your elec compressor off, and see if your overnight system air loss slows down.

[TommyL]

Don’t forget to check drain cock on aux. compressor. Changed ours,now holds air for several days.

Tommy & Cheri .

08 camelot

[dandick66]

1 hour ago, 96 EVO said:

If it's easier, you could just temporarily replace the PPV at your front tank with a plug, and leave your elec compressor off, and see if your overnight system air loss slows down.

Yes, that might be easier.  I’ll let you know how it goes. 

[96 EVO]

I'm sure your getting sick and tired of crawling around under your coach by now 😬!

[dandick66]

2 minutes ago, 96 EVO said:

I'm sure your getting sick and tired of crawling around under your coach by now 😬!

You got that right!  I can’t wait to get this fixed…

[Frank McElroy]

7 hours ago, dandick66 said:

UPDATE 22 MAY

I installed the new replacement pressure control check valve on Friday 19 May - the first one I received was defective.  I started the engine and the pressure built up to 127 PSI.  The rear tank dropped about 10 PSI, thereby indicating the valve is functioning properly.  I drained the wet tank and both the front and rear tanks held pressure.  I drained the front tank and the rear tank held pressure.  Then I drained the rear tank and the front tank held pressure.  I did restart the engine and let pressures build up between each scenario.  Here is the timeline and pressure readings I recorded.                              
19 May 1430 Front 126/Rear 118 (Following governor cutoff and regeneration).     
19 May 1910 Front 111/Rear 104.  (Approximately 5 hours, 15 PSI drop front, 14 PSI rear)
20 May 0630 Front 91/Rear 91. (Approximately 11 hours, 20 PSI drop front, 13 PSI rear)  
20 May 1900 Front 79/Rear 79.  (Approximately 12 hours 12 PSI drop front, 12 PSI rear)
21 May 0700 Front 67/Rear 67.  (12 hours, 12 PSI drop front, 12 PSI rear)
21 May 1830 Front 59/Rear 59. (Approximately 12 hours, 8 PSI drop front, 8 PSI rear)
22 May 0700 Front 49/Rear 49.  (Approximately 12 hours, 10 PSI front, 10 PSI rear)

I’m not exactly sure what my data indicates.  It appears that the front tank dropped pressure a little faster than the rear until they equalized and then they dropped pressure equally.  It leaks about 1 PSI/hour.  I don’t know the accuracy of the transducer and gauges, but I’m assuming it’s +/- 2 percent.  I have not installed the new spring brake hose yet, but I don’t think that affects any readings since it has no pressure when the parking brakes are engaged.        

 

Losing 1 psi an hour it way way below the DOT spec of 2 psi/min (or 120 psi/hr).  I'd say your finished looking for leaks with the brakes not applied.  Time to move on and replace the leaking parking brake hose.

[96 EVO]

3 hours ago, Frank McElroy said:

Losing 1 psi an hour it way way below the DOT spec of 2 psi/min (or 120 psi/hr).  I'd say your finished looking for leaks with the brakes not applied.  Time to move on and replace the leaking parking brake hose.

Absolutely, but he seems like me, and want's his air system as tight as possible.

[Frank McElroy]

53 minutes ago, 96 EVO said:

Absolutely, but he seems like me, and want's his air system as tight as possible.

Yes, his is about like mine but for me what is most critical is that with the coach leveled, it stays level for weeks. 

Mine stays level for months even though the main air tanks slowly, over days, lose air. 

I'll auto level and shut off the system.  My aux air compressor circuit breaker is removed - don't need it because the coach stays level for months. 

I used to leave the auto level on and it kept tweeking by adding or removing air every 10 minutes or so as we moved about the coach.  But for me, I found out just turning it off the auto level system was a much better solution.

[96 EVO]

10 minutes ago, Frank McElroy said:

Yes, his is about like mine but for me what is most critical is that with the coach leveled, it stays level for weeks. 

Mine stays level for months even though the main air tanks slowly, over days, lose air. 

 

 

Same!

I'll leave my auto level on for the day after I set up, shut it down before I go to bed.

At home, mine stays level without the system turned on forever, and my driveway where it sits is on a slight slope.

[dandick66]

I decided to not crawl under the coach too much today.  I did pull the front tank PPV and put a plug in the tank.  I let the pressure build up and I’ll see how it is in the morning.              
                                                 
I did notice the coach squatting in the passenger rear.  I sprayed around the Valid manifold, but didn’t see any signs of leaking.  I’ll investigate it more later this week.

I did do some failure analysis on the PCCV.  I can see why the check valve part didn’t work.  The spring actually broke in 2 places and there’s a lot of rust.  I guess that proves that you should drain your tanks…

[jacwjames]

1 hour ago, dandick66 said:

I decided to not crawl under the coach too much today.  I did pull the front tank PPV and put a plug in the tank.  I let the pressure build up and I’ll see how it is in the morning.              
                                                 
I did notice the coach squatting in the passenger rear.  I sprayed around the Valid manifold, but didn’t see any signs of leaking.  I’ll investigate it more later this week.

I did do some failure analysis on the PCCV.  I can see why the check valve part didn’t work.  The spring actually broke in 2 places and there’s a lot of rust.  I guess that proves that you should drain your tanks…

All my PPV's started to land and I replaced.  I took each apart and they all  had corrosion.  The initial ones were all installed upside down.  The top has a hole it and it should be pointed down, which I assume was to release condensation. 

[dandick66]

1 hour ago, jacwjames said:

All my PPV's started to land and I replaced.  I took each apart and they all  had corrosion.  The initial ones were all installed upside down.  The top has a hole it and it should be pointed down, which I assume was to release condensation. 

Jim, 

That’s interesting.  The valve in the picture has a small piece of red plastic in the top.  The new valve was open at the top.  I emailed WABCO and they couldn’t tell me if the new valve was supposed to have the plastic piece or not.  They did however, tell me it didn’t matter which way the valve was oriented.  I can see that if the valve was mounted downwards, the water could not accumulate in the bottom.  I think I’m going to reorient the one I just installed.  
Back under the coach tomorrow.  I think I’m going to put a cooler under there…

[jacwjames]

Here is the installations instructions of the PPV that I found with the orientation shown. 

I had initially installed mine wrong and when I posted a picture on IRV2 someone said they were installed upside down.  Searched a bunch of sites and finally found the instructions.  Changed all of mine to the correct orientation. 

PPV installation instructions.pdf