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fabosworth

Air Leak: Safety Valve On Air Tank

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I have a air leak on my 1999 HR Endeavor 37ft. I traced to what I believe is a safety relief valve. It leaks until pressure drops to around 80 lbs. Is this normal? My air dryer dumps about every 20 sec?

Thanks

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Thanks, The leak is in a valve on the I think primary air tank, I can push it down and it will only stay down if pressure drops below 80. This valve only has a airline attached and screwed into top of tank. thanks

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The answer is "it depends".

The dryer purges when the air governor reaches "cut-out" pressure. Then as air is used for brakes and suspension (yes, or leaks) PSI drops to the "cut-in pressure. The governor closes the valves on the compressor (in effect turning on the compressor) until cut-out PSI is reached. Cycle repeats.

If concerned about short cycling, start with the standard air brake test. This from an article published a couple of years ago in the FMCA Magazine:

Air Brake System Pre-trip Check

1. Be on reasonably level ground. Block wheels so the coach can not move even with the parking brake off.

2. Start engine and run until full air pressure is reached. Listen for the dryer to purge (about 120 PSI).

3. Shut off the engine.

4. Release the parking brake by pushing in the yellow button (make sure you don't roll, and do NOT apply the brake pedal).

5. After the initial pressure drop, the system should not loose more than 2 PSI per minute.

6. Apply the brake pedal firmly (still with the parking brake OFF).

7. After the initial pressure drop, the system should not loose any more than 3 PSI per minute.

8. With the engine off, ignition on and parking brake off, rapidly pump the brake pedal to bleed down the air supply. During this stage you should watch for the warning light and buzzer at about 60 PSI and then the yellow button (parking brake) should pop out at about 30 PSI.

9. Restart the engine and build up air pressure again. While building up pressure, check how long it takes for pressure to go from 85 to 100 PSI at “cruising RPM”. It should be less than 45 seconds.

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fabosworth, if you are messing around with any of your air lines be sure to have your wheels chocked. The more the better. And have heavy duty Jack Stands under the frame if you plan on getting under your coach. It's hard to dial 911 with your coach on your chest.

BE SAFE.

Herman

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