[Richard]

Reese,

I think we may have some confusion on relief valves.

There is one valve that is at the bottom of the air dryer cannister located behind the driver tag tire. It will pop every time the air compressor on the engine runs through a pressure build cycle. That only happens when the engine is running. Many people will refer to this as the unloader valve. It does two things. It releases the pressure on the engine driven air compressor, and it exhausts any water collected in the bottom of the air dryer when it pops.

There is a small safety valve in the bottom of the wet tank, located underneath the coach, that is intended as a safety device to keep the entire system from seeing too high of a pressure. They are spring loaded and release pressure above a certain point. They can be bought to relieve at different pressures. They look like this https://www.mscdirect.com/browse/tnpla/3...yAQAvD_BwE

I am completely puzzled by your mention of a relief valve on the firewall. Please describe it, or take a picture and post it. I have never seen a Newell with a pressure relief valve on the firewall. I have seen a quarter turn valve on the firewall that is used to supply air to the air doubler. It would release pressure on the system if opened.

So, did you try reducing the pressure on the compressor to 60 psi? What happened?

[rcantrell52]

Richard,
I do a good job of confusing people. The valve that I mentioned is what the service writers call the pressure relief valve. It is located in the compartment with the air compressors.The other tanks and valves I have not seen. I have not gone underneath the coach. I will try and post a picture.
Sorry for being so dense. I appreciate all of your comments.

Sincerely,
Reese Cantrell

[encantotom]

if it is the same as several of the newells i have had, that is the head pressure release on the compressors. when the compressor shuts off, then it releases the pressure going to the compressor so it can start up next time (at full pressure, the compressor will not have enough force to start pumping) and at the same time uses that to blow moisture out of the dryer bowl at the compressor. that either goes to a small tank like an overflow tank or directly under the coach.

my two cents worth.

tom

[Richard]

Is it safe to assume that you want to use an external compressor to keep the coach aired up, instead of using the onboard compressor?

If the answer is yes, is it safe to assume that you want to figure out why the external compressor causes the coach to "hiss" when over 90 psi?

If the answer to both questions is yes, I cannot help you any more without you running the trial I proposed. That is set the compressor to 60 psi and report the results.

If the answer to question one or two is no, then I will find something else to obsess over.

[rcantrell52]

Richard and Tom,
Thank you for your comments. I talked with the Newell Service tech this afternoon that worked on the air leaks last week. He stated that I am hearing the valve in the Air Dryer release pressure. When he was working on the coach last week he had the same situation happen. When the engine was running the Air Dryer function normally. The tech told me not to use the Air Port In, but the port that had the doubler and turn the bulb valve off. 
The answer to both questions is Yes. I will be able to get to the coach either Thursday or Friday PM and try the 60 PSI on the external air compressor. I will let you know the results. Unfortunately I am not mechanically inclined. I can teach a physician how to implant a permanent pacemaker or defibrillator, but I am useless when trying to repair a car much less a Newell Coach. 
Thank you for your input and suggestions.

Reese Cantrell
Newell Coach 1242

[rcantrell52]

Had an opportunity to go to the coach today. I plugged the hose into the out port and started the compressor. The regulator went to 120 PSI, but the pressure gauge on the coach did not move from 40 PSI. Talked to the tech and it appears that the valve was closed and the air could not move to the tanks. Did not have any tools with me to open the valve. Newell ask me to try the Air In port again. Started to hear the air leak at 40 PSI. Newell Service Department believes that the air leak is coming from the Air Dryer. The leak is very noticeable on the driver's side of the coach at the tag axles. 

Reese Cantrell
Newell Coach 1242

[Richard]

Well that is where the air dryer is located, behind the tag on the drivers side.

This is the first time I have ever heard of the air dryer leaking when using external air. In my opinion that is not normal and deserves some attention. I may be overreacting, but I tend to address abnormal behavior on critical systems.

[rcantrell52]

Richard,
I appreciate your feedback. Abnormal behavior on critical systems? Safety issue? Convenience issue? Can you provide further information as to the seriousness of this leak? Is the coach drivable? What is the fix?

Reese Cantrell
Newell Coach 1242

[rcantrell52]

Is this the Air Dryer leak that has occurred with 1242? Is there more than one Air Dryer tank? In some of these posts the location of the tank is different than 1242.

http://newellgurus.com/showthread.php?tid=1443



Reese Cantrell
Newell Coach 1242

[johnkosir]

steerable tags only have 4 tanks not the13 that the older ones have, on 712 the 2 tanks parrell to the frame are for the brakes, the 2 smaller ones 90 degrees to the frame are for the house. there is a check valve between the the tank that gets its air from the 120 volt compressor that is to stop air from going to the dryer may be it is leaking