Air Problems

[Pat M]

After driving over 6k miles, when returning an issue surfaced a day before we returned home.

I am losing air. After staying in a rest area, I let the air build up and after it releases it reads about 110lbs. I released the parking brake and lost about 10lbs, hit the brake for a brake test and lose an additional 10lbs. Eventually it will increase to 110lbs but not as fast as it used too? So I figure I have a air leak? Got the bottle of water and soap out and found some leaks. tighten the Horn and pressure relief valves any valve/nut I found, almost all of then would tighten. Changed the Air valve on front tank and parking brake assembly both were leaking. Started the coach up today same problem, tank filled quickly after starting, lost 10lbs releasing the parking brake, hit the brake pedal a couple of times and it went down to 80lbs. it took about 10 minutes at idle speed to get back to 110lbs. Any suggestions?

Thank and always safe travels,
Pat M
1999 Monaco Executive

[MSHappyCampers]

Pat, I think most, if not all, older coaches like ours will lose air as they sit. Our system discharges air at about 125 PSI. It will slowly lose air over several days. We have auto air leveling that continuously correct itself, so I guess that uses the air. If the main air supply gets below what it needs to maintain the leveling, it has an aux pump that kicks in on the leveling.

[twinboat]

You need to check the rear slack adjuster travel.

They are automatic adjusters, but can seize up.

Chock the wheels, measure how much rod is sticking out of the brake chamber.

Push in the parking brake button and measure the rods again.

If they, or one, got more then 1 inch shorter, your brakes are out of adjustment. Don't just adjust them, fix the auto adjusters.

[Pat M]

MSHC's,
I have hydraulic leveling system and yes the air does drain. This afternoon the gauge was 85lbs, which is better since I tighten and replaced some components.

Twinboat,
Went under the coach today and measures the slack adjuster rod:
With Parking Brake on it was 2-1/8"
With Parking Brake off it was 3/4"
I know how to adjust the brakes and the gap and brakes do not look bad. However, I have to lookup how to fix the auto adjusters?

Thanks to both of you for taking time out of your busy day to answer my question.

Thanks again,
Pat M

[twinboat]

Around 1 inch of travel is pretty normal, I'd say that's not your problem. A few hard brake applications may tighten them up.

[wolfe10]

Originally Posted by twinboat

Around 1 inch of travel is pretty normal, I'd say that's not your problem. A few hard brake applications may tighten them up.

Yup, that will do it unless the automatic slack adjusters are frozen up.

[Pat M]

Hello all,

Did some observations today and here are the results:

FYI: All brake applications were down to the floor.

Parking brake on.
Air gauge started at 60lbs.
Turned RV on and in 4 mins. there was an air release.
2 brake applications, down to 90lbs.
There was a noise right front(plunger?)
Check Gauges Light on, took 1:30 mins. to go out.
Air release @ 3:12 mins.

Parking Brake off
Drop 10lbs to 100lbs.
Waited 5 mins. no movement of air gauge.
2 brake applications down to 85lbs.
Noise again right side.
After 5 mins. up to 90lbs.
2 additional brake applications.
Down to 70lbs.
Check Gauge Light on.
After 5 mins up to 75lbs.
After 10 mins. still @ 75lbs.
After 15 mins. still @ 75lbs and pulled parking brake.

Turned RV off for 1 min.
Pushed brake in to start RV.
Noise again.
Down to 65lbs.
Check Gauge Light on.
Check Gauge Light off after 1 min.
Up to 100lbs in 2 mins.
Air release after 3 mins.


What component is there that sends a signal to a valve to open to refill the tank(s) or maybe a signal is being sent but the valve is not opening when the parking brake is off?

Thanks and as always safe travels,
Pat M

[96 Wideglide]

Compressor governor.

They do fail, and are reasonably cheap to replace.

[Pat M]

96 Wideglide,

Thanks for your response. Do you have an idea on the location as I do not have a clue?

Thanks,
Pat M

[barmcd]

Mine is on the passenger side in the engine compartment. I can see it from the back of the engine. The easiest way to find it is to find you air dryer and trace the 1/4” lines. It’s at the end of one of them.

[96 Wideglide]

It won't be standing on end like Dennis's picture. It will be horizontal with the blue plastic cap facing you. Passenger side of engine, probably bolted to the compressor.

[Pillbox]

Sounds like Brake chamber diaphragms. BE CAREFUL, THEY CAN KILL YOU.
GET SOMEONE TO HELP YOU, LISTEN AROUND THE CHAMBER WHEN BRAKES ARE APPLIED.
This is a dangerous area to mess with. CAUTION, DONT TOUCH IF YOU DONT KNOW.
Sorry about the bold, know someone who was killed messing with spring brakes....
Terry

[Pat M]

Hello all,

Started the RV and air went up to 110lbs then air dryer purged. Turned off RV and had my wife push the brake to the floor and listen for air leaks and did not hear any. Got my soapy water and back under the RV. Found no large leak but there was one at the base of the filter on the Air Dryer, looks like it hasn't been touch for years, as I unscrewed the filter and the rubber gasket fell off. Found the governor and order a replacement and a service kit for the Air Dryer. Also, from reading numerous posts it is recommend to change the unloader valve, can someone tell me where that is?

Thanks for all your help,
Pat M
1999 Monaco Executive

[twinboat]

The unloader valve is at the bottom of the air dryer. Its what purges.