Community Forums

411jeff · 05-08-2016, 12:13 PM

My '98 Monaco Dynasty doesn't hold the air pressure very long.
How long should a system hold air pressure? I'm wondering if I have a leak somewhere. I did do the Air Brake test and that passed. I'm wondering if the leak is on the air ride side. I can shut my RV off and come back in an hour or 2 and the air alarm is on because the pressure has dropped below the operating level. I use to drive a small truck a long time ago and I remember it holding pressure over night (Or my memory is bad) Just wondering if any knows how long the system should hold air.

Thanks,
Jeff

kvm1970 · 05-08-2016, 02:01 PM

Sounds like a leak in your air bags.

loisjop · 05-08-2016, 02:12 PM

Quote:

Originally Posted by 411jeff

My '98 Monaco Dynasty doesn't hold the air pressure very long.
How long should a system hold air pressure? I'm wondering if I have a leak somewhere. I did do the Air Brake test and that passed. I'm wondering if the leak is on the air ride side. I can shut my RV off and come back in an hour or 2 and the air alarm is on because the pressure has dropped below the operating level. I use to drive a small truck a long time ago and I remember it holding pressure over night (Or my memory is bad) Just wondering if any knows how long the system should hold air.

Thanks,
Jeff

You have a large leak. My motor home will hold air pressure for weeks, if not months.

vapor3000 · 05-08-2016, 02:13 PM

Jeff, mix a spray bottle of soapy water, get under you MH and spray every air joint, air filter, air bag, etc you can find. The bubbles will find your leak.

Gary RVRoamer · 05-08-2016, 04:45 PM

Certainly ought to last 24 hours, and many last days or weeks. Mine is currently good for about 36-48 hours, but it has been much better in the past. It's been 4-5 years since I did any leak repairs.

You have hundreds of feet or air tubing and numerous connections, and often several of them leak a tiny bit. Do the soapy water thing, or buy the commercial oily mix designed for leak detection, and get to work. Or take it to a truck chassis shop and have them do it. Not rocket science, just drudge work.

https://www.simplyplumbing.com/catal...leak-detector/

411jeff · 05-11-2016, 08:28 AM

I did notice that the knob to apply the parking brakes sounds like it has some type of air leak? I hear a low air noise from that knob when I release the brakes to drive. Could air be leaking from that?
I have not opened that part of my dash to look at it.

Thanks for all the advise.
Jeff

twinboat · 05-11-2016, 08:35 AM

Yes, the park brake controls leak. So can the switch and fittings screwed into it.

Both parts are common items at truck auto part stores.

Pop the dash out, how ever it's held and take a look and listen.

Spk64 · 05-11-2016, 08:59 AM

On the parking brake as the air pressure lowers below the 60-65 psi it can leak more at the switch. This button is held in place by air pressure. Also a bad leak will eventually not allow the parking brake to release.

Air up the coach, shut down and listen. Go to each wheen location and listen carefully.
If not found this way then the soapy water test is next. Can take time but there are many fitings and valves in the system.

I had a rear ride height valve leak badly but only when in a certain spot when parked and when driving. Caused compressor to cycle every 90 seconds vs the 20-30 minutes it is now.
Also had a rear brake chamber get a hole in the diaphram. This caused air to back feed and leak at many places and park brake would not release at all. Simple repair once the problem was found.

411jeff · 06-07-2016, 09:33 AM

Found the leak in the air valve that controls the passenger slide platform/step.
When I replaced the valve I found that one of my two air tanks has two partitions.
I have one air tank near the rear axle and the other near the front axle. This front air tank is actually two tanks. It's partitioned in the middle. Can anyone tell me what tank services what? I assume the rear tank is for Air Brake system? But why the partitioned dual front tank?

Thanks,
Jeff

twinboat · 06-07-2016, 10:28 AM

Air brake systems all have a 3 tank system.

The wet tank, that receives air from the compressor/air dryer.

The primary tank that supplies air to the rear brakes and the secondary tank that supplies air to the front brakes.

Both primary and secondary tanks are supplied by the wet tank thru check valves that isolate them from each other.

If you Google and download " DOT Air brake 2007 " pdf, it explained the system.