Airing up with an Aux. Compressor.

[FreshAir]

On another thread, "Slides & Leveling" there was some discussion on airing up the coach with an auxiliary compressor so I thought I'd give it a try. Everything worked good except I could get the Rear Air to 120 lb but the Front Air to only 85 lb and the compressor would shut off at the selected compressors 120 lb setting. I was thinking both would fill to the same level.? Am I doing something wrong? An explanation would be much appreciated.

My compressor is only a 3 gal. 125 lb one.

Thank's in advance.
Pat

[Gasman 2]

Did you get coach to ride height? Both front and rear air suspension is supply from the secondary air and the available pressure is reflected in the front gauge.
I'm guessing the air system was still airing up. If the air bags were completely deflated it would take some time to air the complete system up.
The gauges do not reflect the pressure in the air suspension but only what is available. The 85 lbs may take the rear to ride height but I'm not sure about the front.
Hope this helps.

[BFlinn181]

Where did you hook up the auxiliary compressor? The engine driven compressor is plumbed to both air tanks, with a check valve to prevent loss of air pressure in one tank from draining the other. Perhaps your hook up point was only in one tank (rear?) and the front tank was filling by way of a cross connection.

[Matt D]

Pat, I've poured over the air system diagram trying to determine why my small compressor didn't cut it, and why a bigger compressor did just fine.

All I can say definitively is that my Viair 450C doesn't have the capacity to fully air up the coach from zero. My 5 CFM rolling compressor airs the coach up like it isn't even trying hard.

The key isn't the pressure, it's the volume. In the case of the Viair 450C it is rated at 1.8CFM @ 150 PSI. This isn't sufficient for the needs of the coach.

The other compressor I purchased under duress was capable of 5.3 CFM, at what pressure I don't recall. Typically CFM ratings are better at lower PSI values. The larger compressor pushed both Front and Rear air gauges decisively to their normal values, as the coach suspension quickly aired up.

Both compressors were connected to the same "customer air" female coupler in the second PS basement.

I had purchased the Viair thinking it would be adequate to fill up the air bags. In practice, it does pretty good with the front bags, but the rear and tag periodically don't work as well, depending upon how much air remains in the system. With my experience, I now consider the Viair a head start tool, whereas the bigger compressor will quite adequately handle all system requirements.

-Matt

[wmpbauer]

I'm completely flabbergasted by this entire thread. Why mess with this at all? Your system is set up with a compressor and a sophisticated air drying system to deliver filtered, dry, compressed air to meet and exceed the total needs of all coach chassis systems. So why would you even consider introducing humidity which will condense into water in your system. Seems like you're bypassing they system design and you may be bypassing your warranty as well.

Just turn on the key, wait for the oil pressure to come up, engage high idle to about 1200 RPM, and she'll air herself pretty darned quick.

Just my $.02.

[johnnyreno]

Just turn on the key, wait for the oil pressure to come up, engage high idle to about 1200 RPM, and she'll air herself pretty darned quick.

Just my $.02. x2

[dennis45]

Originally Posted by wmpbauer

I'm completely flabbergasted by this entire thread. Why mess with this at all? Your system is set up with a compressor and a sophisticated air drying system to deliver filtered, dry, compressed air to meet and exceed the total needs of all coach chassis systems. So why would you even consider introducing humidity which will condense into water in your system. Seems like you're bypassing they system design and you may be bypassing your warranty as well.

Just turn on the key, wait for the oil pressure to come up, engage high idle to about 1200 RPM, and she'll air herself pretty darned quick.

Just my $.02.

I do this regularly. The reason,
I'm parked in my garage which is below my house (RV townhouse complex) and when I am pulling out I would rather not stink up my garage while I'm waiting to air up.
So I pump up the suspension with my portable, start the coach, back out. No stink..... My nickels worth,

[johnnyreno]

good idea

[Matt D]

Just to clarify, seeing as the train continues to run off the tracks on this topic.

It is ALWAYS best to use the equipment in the manner best described as "normal operation." i.e. Airing up with the stock onboard pump, dryer, etc.

With that being said, there are certain specific times when a calculated decision can be made to use aux air. Having a dryer on this aux source is very cheap, easy, and simple. Any aux source should be regulated to 130 PSI and as dry as possible.

This guidance direct from Spartan as we were deciding how to recover my coach from the side of I-10.

If I called back and asked if they approved of this as a routine practice, I think we all know the answer.

For those of us who have had the requirement to find a solution, either on the side of I-10, or an enclosed garage, we must also assume the risk of this less than ideal solution.

-Matt

[motorhomeguy]

Originally Posted by wmpbauer

I'm completely flabbergasted by this entire thread. Why mess with this at all? Your system is set up with a compressor and a sophisticated air drying system to deliver filtered, dry, compressed air to meet and exceed the total needs of all coach chassis systems. So why would you even consider introducing humidity which will condense into water in your system. Seems like you're bypassing they system design and you may be bypassing your warranty as well.

Exactly, plus if you should ever have an accident or an incident that could be related to the air system, you are up the creek if it is discovered. In order to change anything of this nature, I believe strict safety measure must be followed and approved.

[FreshAir]

Originally Posted by Matt D

Just to clarify, seeing as the train continues to run off the tracks on this topic.

It is ALWAYS best to use the equipment in the manner best described as "normal operation." i.e. Airing up with the stock onboard pump, dryer, etc.

With that being said, there are certain specific times when a calculated decision can be made to use aux air. Having a dryer on this aux source is very cheap, easy, and simple. Any aux source should be regulated to 130 PSI and as dry as possible.

This guidance direct from Spartan as we were deciding how to recover my coach from the side of I-10.

If I called back and asked if they approved of this as a routine practice, I think we all know the answer.

For those of us who have had the requirement to find a solution, either on the side of I-10, or an enclosed garage, we must also assume the risk of this less than ideal solution.

-Matt

OP here, Sorry but this thread has taken on an unexpected assumption spin possibly due to how I asked my question. I'll try to do better.

My main reason for trying an aux. air supply was mainly due to Matt D's post on a thread titled "Slides and Leveling" where he was stranded somewhere on the side of I-10 with no air due to a busted compressor and was able to get rolling again by a bit of McGivering with an aux compressor. I carry a compressor and thought by just adding a double male quick air disconnect,, $7 bucks, to my spare parts supply it just might come in handy some day.

Trying this showed me that I do not completely understand my coaches air supply system as to what tanks do what and how they connect.

My Question is, why did my Front Air gauge only go to 85 lb's and my Rear Air gauge go to 120 lbs when using my aux compressor? The aux compressor automatically stopped at it's 120 lb. setting I bled air and repeated test several times with same result.When I started the engine both gauges went to normal 140 lb area. I did have jacks down during test. ???

Again, thank's.
Pat

[Gasman 2]

Well I probably should not have posted to this tread.
But it appears some are paranoid about this issue and I respect the fact everyone has there own comfort level.
I'm not suggesting that anyone should use an outside source of air.

With that said I have no problem of airing up from my air compressor in the garage. I also drain my compressor after I use it and have a small moisture filter inline.

I come from an era when we did not have air dyers on our trucks. At the end of the day we drained our wet tank (for those that don't know the wet tank is the first tank from the compressor). We ran all winter in Ohio and temperatures can get to sub zero and we never had brake line or a valve to freeze. In the late 80s we used alcohol evaporates to inject alcohol into the air system. Today all of our trucks have air dyers.

I do have some concerned that the air dyers may taken away the importance of maintaining the air system as the driver thinks the air dyer will take of everything and neglect draining the air tanks.

As far as safety and legal issues are concerned it is the driver's responsibility to pre trip the coach or truck and part of that is to run through an air brake check before hitting the road.

And that my 2cents.

[twinboat]

As mentioned, you need to put the air into the wet tank or before it.

Customer air is for blowing things up and is protected from total air loss if the customer rips it out. The system isolates leaks like that.

You may have a tire valve fitting in the air dryer that will charge the whole system or find the wet tank drain valve and tee into that. We often pulled the wet tank drain and connected our tow truck hose to it.

Study your air line plumbing. Your wet tank may be the small section of a two compartment tank. It will have a weld seam around it, closer to one end.

Use a check valve at the tee, so if you rip out your line, no air drains out. You can only put air in. Use stuff approved for air brake use, not Home Depot fittings.

With all that said, keep in mind that engine mounted compressors are in the 25 to 35 CFM range.
Your risking brake loss and E brake application with trying to supply your system with a 2 to 4 CFM compressor.

Everytime your system calls for air, you'll be waiting a long time for buildup. 2 brake applications and your listening to the low air alarms.