Rear Air Pressure Low in Dutch Star

[rowekmr]

Hello

I got a 2000 Newmar Dutch Star 3851 on Spartan chassis that I was going to drive from my house to storage today and noticed during warm up that the rear air tank gauge was just above zero and did not rise at all.

I thought it the tank was less than a certain amount (75psi?) the audible low air warning would sound. There was a red light on in the gauge but no buzzer.

I released the parking brake and checked to see if it would move forward and it did twice. I thought below that threshold (75psi?) the spring brakes would apply themselves.

I shut off ignition and restarted and had same reading. I turned it off and applied brakes until the front gauge was at 50psi and restarted engine, listened to the buzzer and watched the front brake pressure rise but not the rear which stayed at the same mark the whole time.

Not knowing it is a gauge issues or something wrong with the system I shut down and left it here.

When I got the MH the front gauge wouldn't go over 100psi so had the filter replaced and some valve replaced and then both tanks would read 115-125psi.

I just picked up from shop 2 weeks ago and did a 360 mile round trip with no issues. Just thinking I had them repair the air horn system I think they replaced a solenoid.

Any ideas of what is going on?



Thanks

[ILVMYGT]

It sounds like you found the air purge valves and purged air and water from the tank but the pressure reads low. Can you screw a pressure gauge in the purge valve and see what the actual pressure is in the tank? It might take a few fittings to get the gauge plumbed in.

Does the alarm eventually go off if you continue to purge the tank? The pressure gauge and alarm could be 2 different sensors.

[rowekmr]

Well I got a chance to check some things out and here is what I found:
I raised the jacks and MH sat on deflated air bags. I started the engine and let idle.
After idling the front tank went slightly above 125psi when governor kick in.
Rear tanks stays at 25psi with a red light in the gauge but no buzzer sound.
Low air buzzer goes off after about 70psi in front tank
MH air springs raised at all 4 wheels.

I found the lanyard for the tanks and pulled on the one on the passenger side and it sounded strong. I pulled on it for awhile and check both air gauges (left ignition switch on engine off) and the air in the front tank was at 75 psi rear was still at 25 psi.

I started engine again until the front tanks reached 125psi and I heard the governor kick in then shut off engine and left ignition on.

I then pulled the lanyard on the other tank for the same length of time (90 seconds) and it sounded the same as the other tank. After 90 seconds I checked air tank and front was 75psi and rear 25psi.

I started engine and ran it until the air tank was again at 125psi then shut it off and put the jacks back down.

I am thinking it might not be the threaded rod for the height sensor if the rear suspension raises and lowers. Also from the sound of the air being released from the air tanks I am hoping it is just now a gauge issue.

I am wondering if it is safe to drive it to the shop.

[rowekmr]

Thanks for the info!
I am glad it happened at home and not 1 week ago when I was at Indiana Beach. Reminds me how even something small can stop your plans. I will check the tanks then try to crawl under it and look for that rod.

[imgoin4it]

Mine acted the same way when I lost the rear axel ride height rod after hitting a rough area in a construction area on the highway. Emergency roadside service brought and installed a new one and fixed my problem. Cost for the rod was $20.

[larry_cad]

The Spartan chassis for your motorhome has a mechanical link that controls the rear axle ride height. It is a notorious failure item. (from personal experience) It is referred to as "ride height control rod". It is a simple device to change if you have a 7/16" wrench and a spare ride height control rod. Or you can make a new one from threaded rod and two pivot joints. Don't drive the coach with it broken. You will tear up your driveshaft. It is approximately in the middle of the rear axle housing, near the "pumpkin" and should be connected to the frame up above it. One pivot joint or the other is broken.

If you send me your email address via a message, I will forward you a drawing of the rod, along with a bill of material you can use to make a new one for about $20. I carry a spare with me all the time now.

[dougrainer]

1. You have 2 tanks. Failure of 1 tank will NOT lock up the brakes.
2. There is a manual metal lanyard to each tank to release the air. Run the RV for 10 minutes to air up the tanks and then release each lanyard to determine which tank is which on the dash gauges AND determine if BOTH tanks are indeed full and you have a Gauge read out problem. If one tank does not release air, then you have found the tank/valve causing the problem.
3. Replacing the Air Horn solenoid will not cause your problem, it is down stream and IF they did anything wrong, you would hear air leaking out of it when trying to pump up the tank. Doug

[FIRE_UP]

rowekmr wrote:
Hello

I got a 2000 Newmar Dutch Star 3851 on Spartan chassis that I was going to drive from my house to storage today and noticed during warm up that the rear air tank gauge was just above zero and did not rise at all.

I thought it the tank was less than a certain amount (75psi?) the audible low air warning would sound. There was a red light on in the gauge but no buzzer.

I released the parking brake and checked to see if it would move forward and it did twice. I thought below that threshold (75psi?) the spring brakes would apply themselves.



I shut off ignition and restarted and had same reading. I turned it off and applied brakes until the front gauge was at 50psi and restarted engine, listened to the buzzer and watched the front brake pressure rise but not the rear which stayed at the same mark the whole time.

Not knowing it is a gauge issues or something wrong with the system I shut down and left it here.

When I got the MH the front gauge wouldn't go over 100psi so had the filter replaced and some valve replaced and then both tanks would read 115-125psi.

I just picked up from shop 2 weeks ago and did a 360 mile round trip with no issues. Just thinking I had them repair the air horn system I think they replaced a solenoid.

Any ideas of what is going on?



Thanks

First off,
The pressures at which things happen are this:

1. Low air warning buzzer, 60-65 psi depending on how accurate the gauges are and, how the pressure switch is calibrated but, that's very close to when it's supposed to alarm for low air.

2. Parking/Emergency brake auto-application: 20-45 psi. Again, depending on the accuracy of all involved.

For your rear air to climb to 75 only, well, it could be a false reading or, it could be that part of your system is developing a fault. I'm not schooled enough to point you at where to check on this issue. Keep us informed of whatever you find out.
Scott