Sadly, I'm unfamiliar with the systems on air-shift trannies. Hopefully, Bill N Y, MWrench, or others versed in those systems will join the thread.

quote:

Originally posted by towerguy:
Air pressure is normal although at times the alarm (low pressure) comes on and so does the low pressure light.

The transmission selector would not shift out of neutral and the odd thing is the air horns stopped working. I was looking around the engine bay and a friend pushed the horn and it suddenly worked. So naturaly I attempted to select drive and it worked. At this point, everything failed again so the transmission is now stuck in gear. The brakes will release but I can't get it out of drive. And guess what? With the trans in gear, you can't shut of the engine. the other thing I noticed was the gas pedal was either un-responsive or not responsive enough.

The yellow brake release was in its correct position. Even with the low pressure alarm sounding, the yellow knob could be pushed in and the brakes would release. If the pressure was actually too low, the brakes would not release.

Too many symptoms that are interactive. Need to start with some clear first steps.

1. Have you been able to restart the engine after using the engine bay switch to kill it? If not, check that switch. Some of them mechanically interlock until you physically reset them.

2. Do you have an air gauge on the dash (hopefully one that has two indicators on it) that you can observe both indicators going up to about 120psi and STAYING there as the engine idles? You should HEAR the air release at about the 120psi point and the indicators should stop rising. Don't try the horn or the brake pedal or the emergency brake until this is satisfied.

There are certain points as the pressure rises where things begin to function. Somewhere around 65psi the emergency brake may be releasable. The low pressure chimes normally continue until you get the pressure somewhere above 85psi. Any air suspension components normally don't function until you hit the 100psi point. If the pressure goes above 125psi and continues to somewhere around 150psi before you hear the air release the pressure is too high. Like I said, don't do anything until you get the pressure stabilized around the 120psi level.

If not, describe the sequence for us. My guess at this point is you have a leak or a failing compressor.

For an overview of the air components that applies to just about any system with air brakes, try reading through http://www.lowestpricetrafficschool.com/handbooks/cdl/en/5

Mike

Hi Mike,

When the sun comes up in the morning, I'll check the air tank. I went to the site you attached and some of it from my old CDL days came back to me. It has been too long so I'll see what I can find in the morning. It would be nice if it was just a problem of not draining the tank of oil/water. I also will need to remove the battery cable to see if that will reset the tranny to neutral. Bill

towerguy, I have an allison 4 speed and a 250 3208t cat motor. crawl under the coach and slide the shifter manually all the way and then come back one click. i can't remmember whether it is forward or back, but think it is forward and then back one notch. That will then put the transmission in neutral and let the engine crank and shut down. This happened to me once and scared the day lights out of me, till i read the book. I had acciently hit the shift lever while the coach had low air pressure. When this is done, crank engine and let the air pressure build up and try the shift. Hope this takes care of it! sky

Let me first start by saying "Working on a running motor is dangerous and should only be performed by a competent mechanic" Now that Legal is out of the way, perform these test at your own risk!

Your problem is low air psi. 40 psi is 3 times less then what it should be. 120 psi is the norm. As I see it now, you have one of 3 problems.

1) Air leak.
It could be the air compressor discharge line or it could be somewhere else in the system.
-Start up and let the coach idle until warmed up and the air psi stops building at an idle. Floor it and hold the throttle for 30 seconds. Don't worry, it's governed and wont blow up on you. "Floor it" means neutral, peg it and let er rip without holding back any.

Does the air psi rise any? Yes, shut it off and run around listening for air leaks. No, shut it off and let's check some more...

2) You could have a bad gov.
- Disconnect the small airhoses that goes to the air gov and put a plug in THE HOSE ONLY. The air gov is a device that can be bypassed for testing purposes. A lack of air to the gov will cause the air psi to build up. Does that work? Can you get the air psi up to a range of 110 - 125. This is the normal operating range of your coach.

3) You have a bad air compressor.
-With the small airhoses plugged off disconnect the air compressor discharge line and start it up.

Place your thumb over the air compressor discharge fitting at the head of the compressor and check to see if you can hold it down. If you can hold back the air psi with moderate thumb pressure and the small hoses are removed from the air gov then you have a bad compressor.

If you can't hold it back and there are no audible air leaks, then you have a bad air compressor discharge line or a bad air dryer.

-Follow me... The air compressor, discharge hose and air dryer are all in the system before the first check valve. Because the engine is running and loud you will not hear the air leak. When the engine is shut off you will not hear it leak because the check valve is holding the psi in the tanks.

To check this you'll need to hook up another air source to the discharge line and attempt to build up the air psi. This will help you find a leak before the first check valve or anywhere in the system.

I finally gave up and called in an expert, two hours later and I'm walking out the door in search of the rest of my family. The culprit was the air pressure governor/regulator. Total cost for mobile service was $287.04 which seemed very reasonable to me. The weekend is salvaged even though they gave my spot at the RV park away. If I have to dry camp at Wal-Mart, so be it. Everyone have a wonderful Memorial Day Weekend!!! Bill - The newest Barth owner with more to follow on the coach.

P.S. Special thanks to everyone that provided input and to Bill NY for getting me on the right track for a mechanic.

quote:

Originally posted by towerguy:
P.S. Special thanks to everyone that provided input and to Bill NY for getting me on the right track for a mechanic.

Towerguy used the TruckDown.com service to find repair help

Sign on using the screen name guest and the password is guest. Make sure all letters are lower case. It will ask you to sign up - ignore that request and look for the tab that says "continue in guest user mode" or something very close to that.
____________________________________________

You could also use the NTTS directory at NTTS for service requests.

Bill N.Y.

truckdown.com indicates: "Click Here to continue using guest account." The mechanic that showed up knew what he was doing and had me on the road in two hours. His rate was $95 and hour compared to $115 an hour at Camping World. With parts, it came to $287 to replace the governor for the air compressor. He supplied air to the tanks and when there was sufficient PSI, I was able to shift the transmission to neutral and start the engine. The pressure held and it ran beautifully. I highly recommend truckdown.com on the road or locally. I will continue to use this particular mechanic when possible. Bill NY, thanks again for steering me in the right direction.

Sounds like you have a Stone-Bennet air shifter. You can crawl under the coach and move the selector and put it in neutral.

You might check the thread on engine stalling. If you have a bad solinoid like I did, nothing that uses aux 12vdc will work. This includes the Stone -Bennet. The air horns are also operated by the 12vdc aux circuit.

If you do succeed in moving the selector control and get the engine to start but not contiue running you also have a 12vdc problem.
Methinks you have an electric problem.

Hi Gary,

It turned out to be the air pressure regulator. The Stone Bennet is also governed by air pressure, probably as a safety precaution. If the air pressure is too low, the system won't allow you to shift into gear and become a hazard to anyone else. The accelerator pedal also becomes very un-responsive. So, in this case, 12vdc was not an issue, the governor was the culprit as suspected by Bill NY.