Air Dump - final pressure

[Tdccmc]

We've recently purchased a 2008 Diplomat. I have been reading the various posts about dumping air after arriving at your site. What is the pressure reading when your coach is lowered?

[BFlinn181]

Dumping air from your air suspension shouldn't deplete the air stored in your tanks. It only allows the air to bleed out of the air springs and lower the RV. They won't use air again until you start the engine, then they will inflate to ride height.

[xydial]

If your air pressure is more that about 30lbs the bags will automatically re-inflate.

Drop your air pressure by pumping the brakes or holding the parking brake before dumping the bags.

[J -n- C]

We just got back from our first adventure in our new to us '04 Diplomat. When I used the "dump air" switch to lower the Moho, the low air alarm would come on....around 50 or 60 pounds. I also noticed you need to be careful about the steps. Our bottom step ended up only an inch or so off the ground.

Jeff and Carol

[jacwjames]

If the key is in Auxiliary position, turned to the left, you should be able to push the Air Dump Valve to lower the coach and the air in the tanks should not go down, your air gauges should read the normal amount (mine reads about 120 psi). I do not pulse the brake pedal to release air from my tanks.

The air bags should not reinflate when you release the air dump valve if the key is in the Auxiliary position. , or at least they don't on my 2002 Windsor.

If I've been camped for a short time <2 days, in the AM when I turn the key to the On position there will still be air in the tanks so that the Warning Busser doesn't go off with low air pressure alarm.

[Skip426]

Originally Posted by Tdccmc

We've recently purchased a 2008 Diplomat. I have been reading the various posts about dumping air after arriving at your site. What is the pressure reading when your coach is lowered?

The air suspension system in your coach is isolated from the air brake system by a " brake protection valve" , that shuts off the air supply to the air suspension at about 65 PSI; to avoid activating the air park brakes in the event of an air suspension component failure.
The air suspension supply is only from one of the two, ( some chassis use 3) air tanks, so one tank will show lower pressure after the dump.
For future reference , getting an air system diagram from your chassis manufacturer, will help if you ever have problems.

[ShapeShifter]

Originally Posted by BFlinn181

Dumping air from your air suspension shouldn't deplete the air stored in your tanks. It only allows the air to bleed out of the air springs and lower the RV. They won't use air again until you start the engine, then they will inflate to ride height.

I'm sure you're trying to be helpful, but this post is in the Monaco Owner's forum, and Monaco likely does things very differently from other brands, like your Gulfstream. Most Monaco coaches will indeed re-inflate the air bags as soon as you let your finger off of the spring loaded dump switch, until you've finally dumped enough air from the main tanks to prevent that. Annoying, but that's the way it is.

Originally Posted by jacwjames

The air bags should not reinflate when you release the air dump valve if the key is in the Auxiliary position. , or at least they don't on my 2002 Windsor.

Monaco has apparently made some changes between 2002 and 2007: my coach doesn't act that way. I suspect the OP's 2008 Diplomat is more like my coach than yours.

Originally Posted by Skip426

The air suspension system in your coach is isolated from the air brake system by a " brake protection valve" , that shuts off the air supply to the air suspension at about 65 PSI; to avoid activating the air park brakes in the event of an air suspension component failure.

This is likely what the OP has. My understanding is that the protection valves close at 60 PSI, but there may be some variation between individual valves.

Generally, unless you have air leveling, or the air dump is automatically controlled by your leveling jack panel, I believe that most Monaco coaches will tend to re-inflate the air bags until you get the system air tanks below the cut-off pressure of the protection valves. Fanning the service brakes, or pressing the parking brake switch in half-way can speed up bleeding enough air out of the tanks to prevent re-inflation, otherwise it takes a very long time to dump the air out of the tanks using just the air dump switch. Keep in mind that even if you use one of these methods to speed up draining the main air tanks, you still have to hold the air dump switch down long enough to dump the air in the air bags - simply draining the tanks does not drain the air bags.

[BFlinn181]

Originally Posted by ShapeShifter

I'm sure you're trying to be helpful, but this post is in the Monaco Owner's forum, and Monaco likely does things very differently from other brands, like your Gulfstream. Most Monaco coaches will indeed re-inflate the air bags as soon as you let your finger off of the spring loaded dump switch, until you've finally dumped enough air from the main tanks to prevent that. Annoying, but that's the way it is.

Pardon me. I've driven various makes and models of city and interstate buses and when equipped with a dump valve, they dumped air to lower the coach until you restarted or called for the bags to inflate by closing the door or shifted into gear. I'd love to know the reasoning for a dump valve that won't allow the bags to stay that way. What would be the function of a temporary lowering of the RV besides ducking into a garage or something.

[ShapeShifter]

Originally Posted by BFlinn181

Pardon me.

There's no need for that. Like I said, I'm sure you are trying to be helpful.

I'd love to know the reasoning for a dump valve that won't allow the bags to stay that way. What would be the function of a temporary lowering of the RV besides ducking into a garage or something.

I would love to know the reasoning as well!

Temporarily lowering the coach to duck into a garage or something is not an option with this air valving arrangement. The only thing you can do is lower the suspension once parked to aid in leveling and minimize the overall height of the leveled coach, but only AFTER you've dumped enough air from the main air tanks.

A simple valve between the air tanks and air bag ride height control valves would do it: one that closes when the air dump switch is pressed, and opens when the parking brake or gear shift changes state. Or connect it up to the leveling jack system that probably has the intelligence to dump the air properly. I don't know why Monaco decided to do it the way they did, probably because it was simpler and cheaper (and the engineer who designed it never spent any time in an RV!)

The other quirky thing that Monaco does differently is require that the coach be off of the leveling jacks and on the fully inflated suspension before moving the slides. But you had to mostly drain the air tanks when you leveled the coach. That means that when breaking camp, you need to start the engine to build air pressure while raising the jacks. Then when fully aired up, you need to shut off the engine to bring in the slides. Then you can start it again to drive off.

Don't get me wrong, I love my coach. But there are a few details here and there that I wished were done differently. Air dumping (and the consequences) is the biggest one.

[jacwjames]

My response was specific to my coach, others may be different but I do know what mine does.

The airbags will also start to deflate as soon as I start the leveling process so if I choose not to I don't have to press the Air Dump Valve.

I purposely do not fan the brakes to deplete the air tanks so that in the AM when leaving I don't have to listen to the low air alarm and when I start the coach it doesn't take as long to inflate the air bags and/or prep for our departure. The tanks will maintain a higher pressure, +~75psi since this is the point the alarm sounds.

As soon as I turn the key to the on position the airbags will start to inflate.

I know that I have seen other Monaco owners set up and they do fan the brakes but I never asked why.

[Czar Of Poop]

My air dump switch lowers to about 50psi and 6'' of height. But then it will air back up if the engine is still running. So I air down in the aux key position.

[ShapeShifter]

Originally Posted by jacwjames

The airbags will also start to deflate as soon as I start the leveling process so if I choose not to I don't have to press the Air Dump Valve.

Sounds like they tied the dump valves into the leveling jack control panel. A smart move. I wonder why they stopped doing that in the later years?

[ahicks]

Our '97 blows ALL the air with air dump valve depressed. Yes, we get to listen to the buzzer when starting, but only for a minute, and I'm generally outside picking up jack pads etc. anyway...

[Happycarz]

Jacwjames, do you have hydraulic jacks or air leveling?