Small but steady air leak

[truk4u]

Andre,

I can send you my electronic stethoscope if you want.

[ajducote]

Tom,

Thanks for the offer, that would be a big help. Will send my address in email.

Thanks

[LNDYCHT]

In my experience chasing leaks it is seldom fittings and usually devices such as valves. Both of my coaches had leaks at the belt tensioner control valve when I purchased them. The new coach also had a leak at tag axle valve, this leak was very small and not always present.
I found the best method was a stethoscope which is easily obtained at a tool store, I extended the hose on mine with a piece of tube and removed the amplifier device from the end so that it is strictly hose. You definitely know when you are close to a leak.

[johnklopp]

One engineers approach, Make the leak larger and easier to find by reducing molecule size.

If the leak is almost impossible to find, consider putting helium into the air system rather than air. The helium won’t hurt anything on the suspension; but will leak more than 10 times faster for the same size hole and pressure. Helium is readily available at most party stores for inflating children’s balloons. The reason is simply the molecule size. A helium balloon shrinks because the gas molecules within the balloon can slowly pass directly through the permeable rubber of the balloon, air does not. Tires also have a permeability ratio that will allow them to very slowly deflate. A helium molecule may be the smallest molecule in existence. A carbon dioxide molecule (Air) is much larger, composed of one carbon atom and two oxygen atoms.

Remove the helium before driving the bus.