[David and Teresa]

Hello all! I have air leaks that, so far, I haven't been able to find. I watched the videos on Newell's air systems and found them very helpful in understanding how these systems are designed. I bought a leak detector, a few DOT compression fittings, and with bubble soap and lights, started checking all the connections mapping my system as I went.

In all the bays, left side and right, I didn't find any leaks. The front and rear 6-packs seemed fine. Inside, I found a small leak in a 1/4" push-in fitting in the break system under the dash. I replaced it with a compression fitting. I found a leak in the driver's chair, but the previous owner had a cut off valve installed. I closed it and the leak stopped. I still have the dash gauges to check as soon as I can figure out how to get to them. All the toilet connections are good. I have 3 air doors that I haven't got to to check.

I have not been able to get under the coach due to another issue with HWH that only allows the coach to get to travel height.

The results so far: the 120v pump comes on every 4.5 minutes. This seems like a sizable leak to me. Usually, it's been holding for about 45 minutes.

I turned off the 120v and turned on the 12v (which I never turn on). Sure enough, about 45lbs, the pump comes on, however, it's extremely noisy and the gauge doesn't change. I'm thinking the pump is gone. It's a little difficult to get to behind the Aqua Hot overflow tank.

My main question at this point is: Could a defective 12v pump cause the leak? Does anyone know a replacement model? What should I check next?

[CaptainGizmo]

Hi David,

Have you watched my latest video where I cover chasing down leaks in detail?
https://youtu.be/Auf0pzEPGfs?si=paeCfXLZewpfweo8

Your coach is older, but there are still the Usual Suspects I'd like to remind you of...that a lot of folks miss:

1. Your compressor CAN leak from the output fittings, but you'll only detect them when the compressor is RUNNING.

2. Check valves at the tanks can leak (backflow) and cause the compressor to continually cycle since the air is getting lost into the brake system (which notoriously leaks anyways but most don't care since the engine is running to constantly replenish that system.)

3. Modern coaches have an Air Doubler, in which many owners will forget to turn off. The ram-piston constantly works to create high pressure to the air reel and can be the culprit for VERY short cycles.

4. Your Parking Brake and Trailer Charge (Peterson) valves under the dash.

5. I would hope that 12v backup compressor is check-valved to prevent air being lost through it. So I wouldn't suspect it's the source of your leaks.

Once you get under your coach, you'll be able to check all the tanks. I've found our coach has FIVE air tanks!!!!

Hope these help a bit.

[David and Teresa]

Hi David,

Have you watched my latest video where I cover chasing down leaks in detail?
https://youtu.be/Auf0pzEPGfs?si=paeCfXLZewpfweo8

Your coach is older, but there are still the Usual Suspects I'd like to remind you of...that a lot of folks miss:

1. Your compressor CAN leak from the output fittings, but you'll only detect them when the compressor is RUNNING.

2. Check valves at the tanks can leak (backflow) and cause the compressor to continually cycle since the air is getting lost into the brake system (which notoriously leaks anyways but most don't care since the engine is running to constantly replenish that system.)

3. Modern coaches have an Air Doubler, in which many owners will forget to turn off. The ram-piston constantly works to create high pressure to the air reel and can be the culprit for VERY short cycles.

4. Your Parking Brake and Trailer Charge (Peterson) valves under the dash.

5. I would hope that 12v backup compressor is check-valved to prevent air being lost through it. So I wouldn't suspect it's the source of your leaks.

Once you get under your coach, you'll be able to check all the tanks.  I've found our coach has FIVE air tanks!!!!

Hope these help a bit.

[David and Teresa]

Thanks! Nice video. I did check with the compressors running. I need to get behind the dash to check everything there. I don't have a Doubler on my coach. Watching the video, my vintage has way fewer air lines and fittings than yours. It's such a fast leak, I'm surprised I can't hear it with just my ears!

[BusNit]

Check those pocket door valves. Well known to leak and be creator of air loss in quick fashion. Also check the step cover if you have one. That solenoid valve may be in the ceiling of the forward bays. You will find the leak with patience. I am doubting that the leak is from the air gauges themselves but it is possible. Mine are still tight after 30 years.

[David and Teresa]

This morning I checked the rear closet pocket door. Newell didn't make it easy to access. I have no idea how to access the other two. All connections were fine and not leaking. When low on air, this door would slowly close, so I thought it would be the first one to look at.

I ran the coach until it was travel height then shut it off. It will hold in this position in travel mode for about a day before pancaking. While up, I was able to check the tag axel air bags, the height control, All the connections on the air tank in front of the passenger drive axle, the air dryer connections, the front air bags, and an air line that I think is going up the the bedroom slide seal. I only have the one slide out. No leaks.

I'm now about 10.5 minutes before the 120v pump comes on. The brake air holds solid, for at least the hour I was in the coach monitoring everything.

Where to look next? Richard, I need a bread crumb.

[Richard]

Hi David,

Sorry for the delayed help. I was on a air leak mission to help another guru who desperately needed it.

Ok, first things first. On the ping tank in the passenger rear well is a check valve. It allows air from the tank, and therefore the supply side of the air system, to flow towards the 12V pump. It does not allow air from the 12V pump to flow to the entire house system. That way the 12V pump is trying to air up the suspension. There are some piping connections at the 12v pump along with a regulator that provide air to the potties, doors, and slide seals. WARNING WARNING WARNING. I have seen this done about as many different ways as different Newells I have looked at. So when looking at yours think concepts and principles of how the air is flowing. Showing you a picture of mine may do you more harm than good.

There are some air leaks that are really difficult to locate. Areas to check are the shuttle valve solenoids that control the air dumps on the waste tank. The air cylinder for the dump mechanism can also leak internally.

The doors are a real puzzle to find the valve. Look at the carpeted ceiling areas adjacent to pocket doors to gain access.

Take a look at the blowoff valve on the bottom of the big air drier located in the tag drive wheel well.

Take a look at the push pull valve to open the generator. Also try to gain access to where the gen slide is located and listen with the sniffer.

Is it safe to assume that you are NOT leaving the HWH leveling system in AUTO level when parked.

The water separator bowls at the 120V pump and at the rear six pack are KNOWN gremlins.

[David and Teresa]

Hi David,

Sorry for the delayed help. I was on a air leak mission to help another guru who desperately needed it.

Ok, first things first. On the ping tank in the passenger rear well is a check valve. It allows air from the tank, and therefore the supply side of the air system, to flow towards the 12V pump. It does not allow air from the 12V pump to flow to the entire house system. That way the 12V pump is trying to air up the suspension. There are some piping connections at the 12v pump along with a regulator that provide air to the potties, doors, and slide seals. WARNING WARNING WARNING. I have seen this done about as many different ways as different Newells I have looked at. So when looking at yours think concepts and principles of how the air is flowing. Showing you a picture of mine may do you more harm than good.

There are some air leaks that are really difficult to locate. Areas to check are the shuttle valve solenoids that control the air dumps on the waste tank. The air cylinder for the dump mechanism can also leak internally.

The doors are a real puzzle to find the valve. Look at the carpeted ceiling areas adjacent to pocket doors to gain access.

Take a look at the blowoff valve on the bottom of the big air drier located in the tag drive wheel well.

Take a look at the push pull valve to open the generator. Also try to gain access to where the gen slide is located and listen with the sniffer.

Is it safe to assume that you are NOT leaving the HWH leveling system in AUTO level when parked.

The water separator bowls at the 120V pump and at the rear six pack are KNOWN gremlins.

Thanks Richard,

Since your coach and mine are one number apart, I would think they would be as similar as two coaches could be. The blow off valve is good. The gen bay valve is good but the slide is difficult to get to, so I'll try to figure that one out. I'm leaving it in travel mode while parked. Actually, I can't manually raise or lower the HRW due to some problem there, which I'll sort out later. My water separator at the 120v is good, recently replace at my last Newell visit a couple of years ago. The rear I've taken out and just have a gauge there. It's good.

I think I'll focus on the 12v pump area next.

[David and Teresa]

After taking out the water softener and Aqua Hot overflow, it gave me complete access to the 12v air pump. I have an air leak at the pump output. All other fittings are good. Since the pump is not pumping, I'm wondering if there are internal leaks within the pump as well.

Anyway, It's a Thomas 406ADC38/12 12v pump. Quite pricy at a little over $400. Is there a better alternative or should I just replace with the same make and model?

[Richard]

Hmmmm disconnect the pump and cap the line. See what happens with your air useage