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Covelo · 06-24-2018, 08:51 AM

I am on a 6 week trip and 3 weeks into it. Well I have developed a air system head scratcher. The coach builds air just fine when it is cold. After it warms up and I am driving the front tank gauge will start reading 130 and the rear will read 115. Once the front tank reads 130 I start to hear air being released in the vicinity of the dryer. Of course the higher the rpm the more I can hear the release of air. If I use enough air and drop the front tank reading below 115 it stops releasing air, until the pressure builds above 120. When I say release of air it sounds like quick bursts of air, the frequency is dependent on the rpm. Please does any one have any idea what is going on, any suggestions would be appreciated.

BFlinn181 · 06-24-2018, 09:03 AM

When the air compressor reaches preset upper pressure, the governor will shut off the air compressor and air is released via the purge valve on the air dryer. That is normal. If it fails to build up pressure, or is taking a long time to recover from brake use, then it might be an issue. How about when the engine is off, how long does it take air pressure to bleed off? Do the air springs hold air overnight? Do you hear air leaking out after stopping the engine?

Covelo · 06-24-2018, 10:27 AM

It does not hold pressure overnight now. It did prior to now. I can hear a small air release after coach is shut down. Could it maybe a leak some where on the wet tank?

BFlinn181 · 06-24-2018, 10:41 AM

A soapy solution painted on air lines and fittings can maybe find the leak. A professional would use a sonic sensor to find the leak, but they do charge for it.

twinboat · 06-24-2018, 11:18 AM

A leak at the wet tank or lines from it will cause the compressor to not shut down at the proper 120- 125 psi setting but then both gauges, being fed from the wet tank, would climb to 130. You say only one climbs that high.

You could check the 1/4 line from the wet tank to the governer and from the governor to the air dryer. Any leak there will cause high pressure.
Quick bursts of air sounds like the over pressure, safety valves releasing.
All of this would happen whether the engine is hot or cold.

Covelo · 06-24-2018, 11:32 AM

And yes both the front and rear tanks
Read over 120, it’s just that the front tank reaches high pressure first. Guess I’m going to go under and look for a leak