Help with Air Tanks and leaks

[jacwjames]

What is strange is that ~2 months ago I checked all the air bags and fittings for leaks and did not find any.  Air pressure would stay up for ~4 days before low air alarm came on.

What are the odds that all the PPV's fail at the same time.  Talk about planned obsolescence. 

 

[96 EVO]

32 minutes ago, jacwjames said:

 

What are the odds that all the PPV's fail at the same time.  Talk about planned obsolescence. 

 

Probably about the same as winning a lottery!

You don't have those 'auto' drains on your tanks do you?

[jacwjames]

2 hours ago, 96 EVO said:

Probably about the same as winning a lottery!

You don't have those 'auto' drains on your tanks do you?

No auto drains, is that a benefit?

[96 EVO]

I can live without them.

I open my drains frequently looking for moisture, especially since replacing my dryer, and discovering the 'no name' desiccant filter that came installed on the new dryer, wasn't drying the air!

The auto valves are convenient I suppose, but to me they are an unnecessary failure point if they don't completely close. They may be a good thing for a D.P buyer that doesn't know the braking system is any different than their SUV.

 

Edited November 30, 2021 by 96 EVO

[David Pratt]

If you own a coach that does not lose air pressure or air pressure loss is minimal consider yourself lucky. The chassis air in your coaches will leak air, that is the nature of the beast.

I was going through some old Monaco Inc. Files and found this information that was sent to me by Bill D. years ago and thought it might be of interest to the Group, especially in this discussion as this question of what is the allowable leak down rate on a coach is often discussed here on the Forum.

D.O.T. Standard Allowable Leak down. Rev. 06-03-2004

The Department of Transportation (D.O.T.) standard for allowable leak down in the air systems is as follows.

1. A 4 PSI drop in the front air system in a 2 minute time period is allowed.

2. A 4 PSI drop in the rear air system in a 2 minute time period is allowed.

This translates into a 120 PSI drop in a one hour time period. In other words, both needles would be allowed to go to zero PSI in one hour.All of the control valves, relay valves, check valves, etc., have allowable leak rates, even for new components. It is not within the Scope of Monaco Inc., or any Manufacturer, to completely eliminate air leaks. Therefore, the D.O.T. sets the standard for allowable leak down rules in the interest of safety. However, Monaco, Inc.'s leak down rate is set as follows:

Monaco, Inc. Allowable Leak down

1. A 6 PSI drop in the front air system in a one hour time period.

2. A 6 PSI drop in the rear air system in a one hour time period.

This translates into an approximate 60 PSI allowable leak down rate, for each air system, in the overnight park mode(10 Hours). This is an extremely small air leak. The Monaco, Inc. and other Manufactures standard is 20 times more stringent than the D.O.T. required safety standards, which allows 120 PSI per hour.

[tmw188]

Well there you have it.

[Paul J A]

BUT, was the "Standard" ever attained and confirmed before the NEW coach went out the back door to the parking lot. Thank god it's a pressurized leak. Much easier to find.

[jacwjames]

Well, that much of a pressure loss may be acceptable but it still doesn't give a warm and fuzzy feeling.  Like I said, ~4 months ago it would take +4 days for my low air alarm to come on.  Then in TX is was overnight, that was concerning enough but then at one point I parked the coach to look at an exhibit in the one of the national parks and 30 minutes later the low air alarm came on.  This didn't happen again but at that point I decided to high tail it home. 

Today I made 6 ramps to get the coach off the ground so I could completely drain the air.  I then pulled 2 of the 4 PPV valves off, one has the accessory ports and the other doesn't but I think I'm just going to go ahead and standardize.  There are a couple check valves I'm going to go ahead and replace and a larger PPC I'm going to change, I want to fix this problem once and for all.

I took the time to take the 2 PPV's apart.  Both springs were extremely corroded and one of the diagrams did look like it was cracked where it flexes.  There is a small hole at the top of the spring cover that allows air in, this must contribute to corrosion.  Since the spring is on top any flacks off the spring, this may contribute to the leaks.   Here's a picture of the two PPV's. 

[96 EVO]

Ah!

You've had plenty of moisture in you're air system at some point! 

[Ivan K]

32 minutes ago, 96 EVO said:

Ah!

You've had plenty of moisture in you're air system at some point! 

Not necessarily in the system, the inside part looks nice clean but the spring side is open to outside humid atmosphere. It still should not matter unless the membrane gave up.

[96 EVO]

9 minutes ago, Ivan K said:

Not necessarily in the system, the inside part looks nice clean but the spring side is open to outside humid atmosphere. It still should not matter unless the membrane gave up.

So that spring housing is vented to atmosphere?

[Ivan K]

5 minutes ago, 96 EVO said:

So that spring housing is vented to atmosphere?

 

[96 EVO]

Got it!

Needs to be at atmospheric pressure or the compressed air wouldn't be able to compress the spring.

[jacwjames]

Yes, it is vented to air.   I'm sure the corrosion doesn't help. 

I've got 4 of the PPV's on order.  Should have them in my hands by Friday, should  take too long to install.  I'll then check the rest of the fittings/connections and fix what's needed. 

[96 EVO]

The bits of corrosion off the spring is likely what damages the rubber seal.

Guess they are a wear item, that need to be replaced on occasion.

[tmw188]

So help me understand this. When you say low air alarm comes on you have the air leveling system on auto level? 

[Jimmer]

Where can I find the 03 Windsor pneumatic schematic?

 

[miacasa_2000]

Food for thought.   When I replaced all of mine I also replaced all the fittings with DOT approved swivel fittings. Reason being if I needed to replace the ppv again I would not have to take any airlines out of the fittings again and avoid all that goes along with that. I was a little concerned about leaks at the swivel so I checked them often and no leaks. 

Roy  2003 dynasty

[jacwjames]

12 hours ago, tmw188 said:

So help me understand this. When you say low air alarm comes on you have the air leveling system on auto level? 

No auto level.  The low air alarm comes on when parked with or without the jacks down.  The air bags stay up. 

The PPV's protect the air system from a catastrophic loss mostly to maintain braking capability and are plumbed between tank and the ride height valves.  When they leak the tank psi drop causing the low air alarm to come on.  While driving the compressor kept up with demand but when parked the air would leak down.  Sometimes taking overnight, other times faster which is when I decided to head home. 

 

8 hours ago, Jimmer said:

Where can I find the 03 Windsor pneumatic schematic?

 

I don't have a newer version of the air system for my coach but found this one somewhere.  I don't think they have changed much and based on the parts listed are the same as mine.   It even is color coded. 

AIR SYSTEM Dynasty and Windsor.pdf

1 hour ago, miacasa_2000 said:

Food for thought.   When I replaced all of mine I also replaced all the fittings with DOT approved swivel fittings. Reason being if I needed to replace the ppv again I would not have to take any airlines out of the fittings again and avoid all that goes along with that. I was a little concerned about leaks at the swivel so I checked them often and no leaks. 

Roy  2003 dynasty

I am going to look at the entire system and may replace some components that may be prone to causing problems.  There are a couple check valves in the system.  There is also one larger PPV valve on the rear tank that I have not been able to get a part number off of.  May have to remove to get a good look at it but first I am going to get all the smaller PPV installed and tested first before taking other stuff off. 

On 11/24/2021 at 8:39 AM, miacasa_2000 said:

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

I ended up ordering mine from Advanced Auto, they will be at the store Friday for pickup.  I ordered 4 but may get at least one spare to carry. 

After I dug into pulling one of the PPV's off they aren't that hard to change.  Having my coach raised ~6" on ramps it does make it easier but if a push I could get to them to change if stuck some where. 

Prior to my trip I did buy some repair couplings for the tubing, I am going to revisit the different sizes and make sure I have all that I might need.  Since my coach is 20 years old stuff is bound to happen so I am going to be proactive in inspections and preventative maintenance.  That's why I just went ahead and replaced both my AC/Heat Pumps, hopefully one less thing to worry about. 

[tmw188]

Asking about it because I have never heard a alarm even after sitting a month, maybe it’s been disconnected? The coach will air up in 2-3 min. 

[David Pratt]

You should only get a "LOW AIR ALARM" when the Ignition is in the "ON" Position and the leveling system is in Manual or Travel Mode!

The low air alarm should not come on when in Auto Level Mode because the Leveling System cuts out the Chassis System when selected in Auto Level. When you are in Auto Level the leveling system only provides air to the Air Bags and not the Air Tanks. The Leveling Compressor will provide the air pressure need to keep the Coach Level.

In Manual Mode the Level of the coach is maintained by the Chassis Air System and when the air in the tanks get depleted it can cause the coach to go out of level. The Low Air Pressure Switch is located on the front air tank.

 

[jacwjames]

2 hours ago, David Pratt said:

You should only get a "LOW AIR ALARM" when the Ignition is in the "ON" Position and the leveling system is in Manual or Travel Mode!

The low air alarm should not come on when in Auto Level Mode because the Leveling System cuts out the Chassis System when selected in Auto Level. When you are in Auto Level the leveling system only provides air to the Air Bags and not the Air Tanks. The Leveling Compressor will provide the air pressure need to keep the Coach Level.

In Manual Mode the Level of the coach is maintained by the Chassis Air System and when the air in the tanks get depleted it can cause the coach to go out of level. The Low Air Pressure Switch is located on the front air tank.

 

I don't have auto level

The alarm is coming on when I turn the key to start the engine when the air drops below ~60psi(from memory).  In the past the air would stay up for days, now it goes off sitting over night and while on my trip it went off after <1 hour.  My air gauge shows both front and rear tank going down.  The PPV valves on both tanks were  leaking, at least 4 of them, still looking at the system to determine what else I may have to change to make sure it's fixed correctly.  I'm going to change the fittings and carry the old as spare. 

The schematic I posted before is for a Dynasty bat appears my system is pretty close.  The PPV were the same part number after I got 2 off, some the fitting numbers are different but I can find the fittings locally from different sources. 

[jacwjames]

Tore into the rear air tank fittings this afternoon.  I'm going to go ahead and change some of the larger 5/8" fittings since I have most of the other fitting/components removed and it would be easier to do it now then have to take everything back off later.  There is not enough clearance in some cases to rotate a part off without removing the adjacent one.  

Definitely a learning experience as to how everything is connected and interacts. 

I would suggest that if you have not looked at the air system on you coach that you take the time to do it.  In the event you have a problem it will save a lot of head scratching trying to figure things out. 

After checking around locally I have all the parts on order and/or will go pick them up locally tomorrow.   There is a local store that sells a number of items so I'm getting some of the connectors there.  One part won't be here until next week but I'll have enough to do in the mean time.  

I removed a 3rd PPV valve and took it apart, looks the same as the others.  On the rear tank there is a part that looks like a PPV but is larger and is a check valve from the front tank to the rear.  I removed the top cap which has no vent hole and the insides look like new, going to replace anyway. 

Any suggestions as to what thread sealant would work best. 

[Notn2bars]

Jim, glad you are able to figure things out.  The thread sealant we used was Rectorseal TRU-BLU pipe thread sealant.  It is an excellent sealant and none of our connections leaked after applying it.  God Bless, Ed & Sylvia

[jacwjames]

2 hours ago, We2dynasty said:

Jim, glad you are able to figure things out.  The thread sealant we used was Rectorseal TRU-BLU pipe thread sealant.  It is an excellent sealant and none of our connections leaked after applying it.  God Bless, Ed & Sylvia

OK, looks like they carry it at Home Depot, I'll stop and get some when I go get some other parts tomorrow. 

Thanks