[Tim]

Look for leaks everywhere. There is no end of potential leak sources.

If you lose air that fast you should hear the leak. Leak detection and repairs is a huge subject and has been covered extensively on the forum.

[DON]

Cliff,

Like Jon said, air leaks can literally be anywhere.

However, one leak I had which also caused my gauges to leak down fairly fast was a leak in one of my air lines to the dash brake gauge. Although it is only a 1/4″ line, after I located it and had it fixed, my Aux air now holds air up to several days and my F/R brake tanks hold air several weeks (I’ve haven’t sat more than two weeks anywhere the last three months to actually test these tanks longer).

However, between Jeff’s & Prevost, I’ve had all the other big items which can cause air leaks updated.

[Archived]

Here is the list of leak detection methods, in order of going from the easiest to the most difficult to find…..

Your ears. You can near big ones. If needed supplement your ears with a stethoscope because even if you hear the leak, sometimes the noise is hard to isolate. A stethoscope at that point becomes a direction finder.

The stethoscope. It will hear the larger ones just by placing it near fittings.

Soapy water. If you use the good stuff that is available at A/C parts stores it works over a long period and will show even small leaks. Soapy water will do the job on most leaks.

Ultrasonic Leak detector. This device is pricey, but if you are determined to find your own leaks this will “hear” even the smallest leaks, but it has limitations. It is not going to find a leak in a rubber device such as air bags or belt tensioning bellows.

A bubbler or leak down gauge. This is a home made device that requires you to determine if a circuit leaks, then to connect to the circuit, moving downstream checking along the way. This is time consuming and requires patience. But it is a fool proof way to detect leaks down to the slowest rate.

Or you can mortgage the house and turn the bus over to someone and tell them to fix the leaks. You would be amazed at how much money that can eat up, and how you still end up with leaks. Only very rich people, or those whose coach is under warranty can select that option.

[Archived]

I just went through this same exact thing with my coach Cliff. It was a fitting on one of my rear brake chambers. Mine was an audible leak, so didn’t cost much to fix. I would let your coach air up to full pressure and then shut the bus off. Then go outside and sit next to each wheel. If you have a leak like I did you’ll be able to hear it.

But My coach did exactly like yours. Wouldn’t lean but aux air would go to zero within 30 minutes followed by the draining of the other gauges.

[Peter]

Please explain how you detected a leak at a brake chamber. When the coach is parked with the parking brake engaged there is no pressure beyond the relay valves, and zero pressure at a brake chamber. When you release the parking brake you apply air to the parking brake chamber, but if the engine is running it takes a huge leak to hear it.

[Peter]

The only way a brake can will leak is with the park brake released , not with it on it has no air too it , unless it’s a R12 or R14 relay valve that’s leaking and if they are leaking it still will not be from the brake can

Edit If the park brake is on

[John]

I stand corrected. Just reviewed my invoice from Parliament. It was a fitting to the brake relay valve that was leaking, not the brake chamber.