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Air pressure 30 pounds higher on top gauge

May 18, 2015, 01:42:24 pm

Looking for some insight on this issue, My air pressure is running 20 to 30 pounds higher on the top gauge in the dash then the bottom gauge, I changed the governor thinking that was the problem but it didn't change it, Would I have a front solenoid that is sticking or not working? When the bottom gauge gets to 125 its cycles like it is supposed to, any help appreciate, Adam

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Re: Air pressure 30 pounds higher on top gauge

Reply #1 – May 18, 2015, 02:44:40 pm

Swap the air lines on the gauges and see if the reading changes

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Re: Air pressure 30 pounds higher on top gauge

Reply #2 – May 18, 2015, 02:49:40 pm

The compressor on the engine gets air from the intake manifold (filtered air) sends it to the air dryer, then thru a check valve on the wet tank inlet (near the rear axle) then it goes to the two front tanks (near the front axle and both have a check valve at the inlet.  These tanks supply air to the brakes, suspension, air horns,  and door step.  Air gauge reads the pressure of these tanks.  Governor causes the compressor to cut in or out according to pressure in the wet tank, so it would have no effect on your problem.  You could have an air leak somewhere causing one tank to drain faster than the other.  It's not unusual to have different readings, but when parked and no air being used both tanks should read the same when the compressor cuts out.  If that is the case does one tank then bleed down? The wet tank will supply air to the tank needing it until the pressure drops low enough for the compressor to come on.  What happens to the pressure if the engine is turned off after the compressor cuts out.  If it drops to a very low reading it would indicate an air leak, or maybe defective check valves on that tank and the wet tank.  With the engine off drain all the air from the wet tank, front tanks should maintain pressure.  If the pressure of one tank is always lower, you could have a defective gauge. 

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Re: Air pressure 30 pounds higher on top gauge

Reply #3 – May 18, 2015, 04:04:42 pm

It could be a faulty gauge but I find that slim, I don't have any leaks, Coach holds air for 5 to 7 days, even after sitting for 3 days the gauges remain 25 pounds difference in pressure, The only thing that I did different when it started changing was I adjusted the air bag height the front was 1 in taller then the back so i lowered the front bags 1/2 in and the back bags raised 1/2 in, they are now all at 8.5 in from frame to  frame,  when I got the coach 2 months ago the front leveling valve rod was removed, Keath from MOT came over to work on it and replaced the arm and 1 solenoid the night I picked it up and everything was fine other then the front being set at 9 inches and the back was at 8 in, so I made the adjustments while traveling and was able to watch what it did, The last 800 miles is where I started having this pressure issue and I thought it was the governor, It could be the gauge I guess but think it is something else in the front,

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Re: Air pressure 30 pounds higher on top gauge

Reply #4 – May 18, 2015, 04:46:59 pm

Adam, wish I could help.  But the air bag changes, I am not sure I understand.  Are you saying the coach was parked with auto leveling "on"and you thought the air bags should be the same height but were not and so you adjusted them to be the same? 

Anyway, I would try switching the gauges as suggested.  Try to separate gauge question from the other adjustments.  But mine did this, was bad gauge.

Kinda wonder too, when the governor ran and topped out at the 125 psi or so, did both gauges reach that level?  You indicated that when one gauge hit the 125, the governor stopped.  So the other gauge only got to 105 or so psi?

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Re: Air pressure 30 pounds higher on top gauge

Reply #5 – May 18, 2015, 05:38:59 pm

Michael
The heaght on the bags was in travel not parked, and when it bypasses it is 125 on the bottom gauge and the top gauge reads 145, I will switch the lines on the gauges and see if that is what is wrong,

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Re: Air pressure 30 pounds higher on top gauge

Reply #6 – May 18, 2015, 07:00:06 pm

145 psi is too high, 125 psi is the correct pressure for the governor to cutout.  Sounds like one gauge is defective reading high.  Remember to drain the tanks before changing the lines. 

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Re: Air pressure 30 pounds higher on top gauge

Reply #7 – May 18, 2015, 11:34:53 pm

If it's reading 25psi high....it will read 25psi when pressure in tank is zero. Try that (pump breaks to let all air out).

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