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Author Topic: Monaco Knight Air pressure gage  (Read 743 times)

tcutsing

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Monaco Knight Air pressure gage
« on: December 27, 2017, 05:10:52 PM »
I bought 2000 Monaco Knight this summer and already having more troubles than I hoped for - but who actually hopes for troubles???

Anyway, I'm having a low air pressure problem, the parking brake is locked on and the air ride has gone flat.  There is only has a warning light, no gauge.  Can I convert it a gauge using the existing sending unit?  And where is that unit?

Also, I may have to charge the system from the air compressor in the garage, any tips on how I might do that?

A bad air compressor will be an expensive repair, any other ideas what could cause low air? 

Thanks,
Tom C.

Gary RV_Wizard

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Re: Monaco Knight Air pressure gage
« Reply #1 on: December 27, 2017, 05:38:59 PM »
I like an air gauge, but it seems irrelevant in this situation. You have insufficient air pressure to operate the brakes (about 65 psi) and far too little to lift the suspension (typically 100+).  You need to find the leak(s) rather than worrying about gauges. Or replace the faulty compressor (more likely clogged air dryer).

You have a port up front somewhere that will allow air to be forced into the system, maybe in a front storage bay or behind an access panel in the front cap. If you have a generator access panel, open that and look around for a standard air chuck port (not a tire valve stem - a quick-connect port).
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Iron Horse

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Re: Monaco Knight Air pressure gage
« Reply #2 on: December 29, 2017, 07:43:29 AM »
I would think that if you are in freezing temperatures the system has frozen up somewhere in the lines. If the air dryer hasn't been serviced that would do it, I think the air dryer desiccant filter is supposed to be changed out around every three years. I wouldn't suspect the compressor yet. Try to warm up the system somehow and I bet it will start working again........Good Luck......Iron Horse
2007 Winnebago Journey 36G

Iron Horse

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Re: Monaco Knight Air pressure gage
« Reply #3 on: December 29, 2017, 07:54:43 AM »
Me again.....When I worked on the Railroad I had a Huge service truck that I brought home and it had air brakes. At least once a year during winter it would freeze up and I used a torpedo heater to blow hot air under the truck for about 45 minutes and it would thaw out. Be careful and not get too close as it would burn the paint.
2007 Winnebago Journey 36G

tcutsing

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Re: Monaco Knight Air pressure gage
« Reply #4 on: December 29, 2017, 12:45:33 PM »
Thanks for the feedback.

I did crack open the main air line to make sure the line wasn't blocked with ice and it did seem to have good air flow.

A little more history on my RV and the issue.  The RV is a smaller one (34') so it has hydraulic brakes and hydraulic leveling.  The suspension is the air ride and the parking break is air actuated and there's a step cover slide that runs off air. 

I was in Michigan for the holidays and it was bitter cold but everything was working.  It wasn't until I was almost home in North Carolina (~600 miles) before the low air issue started. 

Today I installed a gage at the tank and an air port.  With engine running it only produced about 30 psi so I charged it to 110 psi from the home compressor.  The gauge was holding fairly well, maybe a small leak somewhere, but nothing i could hear easily.  With the tank full the suspension air bags filled and allowed the parking break to release but to my surprise the low air light was still on. (still haven't found that darn sending unit).  is it possible that what ever is causing the low air light to stay on is also causing the low output on the compressor?

I will go investigate the air dryer, see if I can learn anything there.

Thanks again.
Tom C

Iron Horse

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Re: Monaco Knight Air pressure gage
« Reply #5 on: December 29, 2017, 03:13:59 PM »
Is your motorhome a diesel pusher? Does it have a diesel engine in the rear.....I don't know enough about your MH to say, but if you have an air compressor you more than likely have air brakes......can you give more info on your motorhome.................Iron Horse..................
2007 Winnebago Journey 36G

tcutsing

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Re: Monaco Knight Air pressure gage
« Reply #6 on: December 29, 2017, 04:37:31 PM »
Yes, it's a diesel pusher, 5.9L cummins on a Roadmaster chassis. Monaco Knight 34Y, 4 wheel anti-lock disc brakes.  1 air tank up front.  Definitely not air brakes, would probably stop better if it was. 

I followed the line from the compressor to the tank, no air dryer either. 

I charged the system again, this time to 125 psi and the low air light did go off.   Waited about 10 minutes and the pressure only dropped to 110psi - a small leak somewhere but not enough to cause this problem.  I drained air until the light came back on at about 65psi.  Then I ran the engine at 1500rpm for several minutes and the pressure didn;t go up at all. 

At this point I'm thinking its got to be the compressor.   :-(


Gary RV_Wizard

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Re: Monaco Knight Air pressure gage
« Reply #7 on: December 29, 2017, 07:36:25 PM »
A failed compressor is conceivable, but unlikely, even after 16 years of hard use. It seems much more likely that the compressor outlet is plugged. Where did you disconnect the main air line? Right at the compressor outlet. or elsewhere?

The 2000 Knight does indeed use a hydraulic brake system rather than air - it's described right in the owner manual!   I see no mention of an air dryer either. though the tank has an automatic drain pop-off in addition to the manual drain. It appears to be the Monaco R4r chassis

https://www.monacocoach.com/resources/media/manuals/2000_Knight.pdf
« Last Edit: December 29, 2017, 07:38:07 PM by Gary RV_Wizard »
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL