Unstable air pressure gauges

Topic: Unstable air pressure gauges (Read 825 times) previous topic - next topic

Unstable air pressure gauges

January 28, 2012, 05:22:04 pm

Driving at a steady 60 mph, foot off the brake pedal. My air gauges fluctuate between 90psi and 110 psi every 60 seconds or so. Do I have a leak? Brakes are working, but today I got some sqealing as if the pads wdre still rubbing on the disk.

Re: Unstable air pressure gauges

Reply #1 – January 28, 2012, 07:23:01 pm

A leak or an air dryer acting out...

Re: Unstable air pressure gauges

Reply #2 – January 28, 2012, 08:48:44 pm

Are the gauges VDO or the Stewart Warner gauges. I had to replace mine with mechanical VDO gauges to get the proper reading.

Re: Unstable air pressure gauges

Reply #3 – January 29, 2012, 06:53:45 am

Quote from: John S – January 28, 2012, 08:48:44 pm

Are the gauges VDO or the Stewart Warner gauges. I had to replace mine with mechanical VDO gauges to get the proper reading.

They are VDO gauges. This just started to happen yesterday. Guess I'll ad brakes to my "to do List" when I get to Classic Coach. Sigh.

Re: Unstable air pressure gauges

Reply #4 – January 30, 2012, 07:03:14 am

If it takes a min to get down to 90 then coes up, you have an air leak somewhere. The air dryer could have a bit if dirt stuck or one of the regulators for the air step or slide cover is bad. Those are the usual suspects I check first.

Re: Unstable air pressure gauges

Reply #5 – January 30, 2012, 09:16:20 am

My vote would be bad gauge readings, indicating a voltage supply to the gauges, it is unlikely both gauges would become goofy at the same time unless the voltage supply or grounding is erratic. To go up/down 10 psi in 60 seconds is not normal, if it were a actual loss of pressure, when it droped to the point the governor started to pickup, the pressure would go up to the 120 psi area.
So why I vote on the voltage issue, loose wiring, corroded terminals, something other than actual air pressure change.
Normal governor range is approx 105-120 psi range, so is worth a more in depth thought, sometimes the facts are slightly different from what is thought.
Some times installing a actual gauge in the system is the simple way of trouble shoothing, when using electric gauges.
Lots of fun, playing with big boy toys ain't it

Re: Unstable air pressure gauges

Reply #6 – January 30, 2012, 11:24:16 am

My vDO gauges are manual so voltage should no affect them. My original gauges were electronic and were not reliable.

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Unstable air pressure gauges

January 28, 2012, 05:22:04 pm

Re: Unstable air pressure gauges

Reply #1 – January 28, 2012, 07:23:01 pm

Re: Unstable air pressure gauges

Reply #2 – January 28, 2012, 08:48:44 pm

Re: Unstable air pressure gauges

Reply #3 – January 29, 2012, 06:53:45 am

Re: Unstable air pressure gauges

Reply #4 – January 30, 2012, 07:03:14 am

Re: Unstable air pressure gauges

Reply #5 – January 30, 2012, 09:16:20 am

Re: Unstable air pressure gauges

Reply #6 – January 30, 2012, 11:24:16 am

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