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Old 10-05-2016, 08:55 AM   #1
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Join Date: Oct 2016
Posts: 152
1987 Beaver Marquis air system

I wonder if anyone here has the same motorhome and can provide some guidance.
This is a recent purchase and my first RV and it has an air leak. It actually cannot build up enough pressure to be drivable.
I suspect that the line from the compressor to the back is the culprit. I can hear a constant hiss from the engine compartment (bed raised) after shutting off the engine.This lasts about 30 to 60 seconds.
I check the fittings on the compressor with soapy water and they are fine.
Following the line going down (on the driver side), it goes to underneath the RV. When I grabbed it with my fingers and moved it and pulled and pushed a little on it, the sound of the hissing air changes.
I tried to track the line underneath but it is difficult to move under the RV and it was getting late so I decided to do some internet research. Nothing useful turned up.

Couple of questions.
I have previously look under the RV and cannot find the air dryer. Does it have one? (and I am too blind to see it).
Does the air hose go directly to the air tank in the back???
If I replace the hose, where do I buy one and what kind?

I know, it is a little long winded, but I hope I got enough info in there to describe the problem.
It also seems that my air pressure in the tanks is holding despite the leak in the hose. Check valve?
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Old 10-12-2016, 06:09 AM   #2
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Location: Charlotte NC area
Posts: 254
Here is a basic diagram to show you how things run. The air leaves the compressor and goes to the drier,then from the drier to the wet tank. The wet tank has a drain in the bottom make sure it is closed. The line from the compressor to the dryer could be split they deal with a lot of heat and can fail.
You are going to just have to look for the dryer min eon my foretravel is in the back right hand corner of the engine compartment.your kind of stuck till you can build enough air pressure to release brakes.
1991 40' Foretravel Grand Villa Unihome
Detroit 6V92TA 300Hp
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Old 10-12-2016, 10:44 PM   #3
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I called Gillig, who made the chasis and found out the compressor discharge hose is 73" long.
With that information a trip under the motorhome was more fruitful.
I found the ss braided hose connects to another hose which leads to the air dryer (which is in the very front of all places).
The connection is burried under bunch of other hoses and wires that it would be a nightmare to get to while working on my back in a gravel parking lot.
I spliced the damaged hose and eliminated the leak for now. I will get it into a shop and have a mechanic make the fix. It will be much easier for them if they put it on a lift
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Old 10-13-2016, 05:58 AM   #4
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Location: Charlotte NC area
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Good deal They use a stainless steel wrapped hose because the hot discharge air from the compressor will fatigue a unwrapped hose quickly.
1991 40' Foretravel Grand Villa Unihome
Detroit 6V92TA 300Hp
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Old 10-13-2016, 06:04 AM   #5
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For future reference, the OP might want to consider posting questions like his on the Forum of the Beaver Ambassador Club. For older Beavers this is still the best repository of expertise I am familiar with.

Also, if you are not aware, Beaver Coach Sales and Service (BCS) of Bend OR purchased the rights to the Beaver name after Navistar divested the Monaco brand. BCS has been an invaluable source of parts and advice for me over the 5 years I've owned my MH.

Joel (AKA docj)
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2000 40' Beaver Patriot Thunder Princeton CAT C-12
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Old 01-14-2017, 09:19 PM   #6
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Yep. The Drier is in the front, can't remember which side. I changed mine about 10yrs ago, have a rockwood on the same chassis as yours.
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