Impossible to find air leak

ultra sonic air leak detection, have a google on that one.

Leak Detection
Since air leaks are almost impossible to see, other methods must be used to locate them. The best way to detect leaks is to use an ultrasonic acoustic detector, which can recognize the high frequency hissing sounds associated with air leaks. These portable units consist of directional microphones, amplifiers, and audio filters, and usually have either visual indicators or earphones to detect leaks.

Ultrasonic leak detection is probably the most versatile form of leak detection. Due to its capabilities, it is readily adapted to a variety of leak detection situations. The principle behind ultrasonic leak detection is simple. In a pressure or vacuum leak, the leak flows from a high pressure laminar flow to a low pressure turbulence. The turbulence generates a white noise which contains a broad spectrum of sound ranging from audible to inaudible frequencies. An ultrasonic sensor focuses in on the ultrasonic elements in the noise. Since ultrasound is a short wave signal, the sound level will be loudest at the leak site. Ultrasonic detectors are generally unaffected by background noises in the audible range because these signals are filtered out. This means leaks can be heard in even the noisiest environments.

The advantages of ultrasonic leak detection include versatility, speed, ease of use, the ability to perform tests while equipment is running, and the ability to find a wide variety of leaks. They require a minimum of training, and operators often become competent after 15 minutes of training.

Due to the nature of ultrasound, it is directional in transmission. For this reason, the signal is loudest at its source. By generally scanning around a test area, it is possible to very quickly home in on a leak site and pin point its location. For this reason, ultrasonic leak detection is not only fast, it is also very accurate.

 

Possibly in the splitter of your gear box. One of the hardest places (IMO) to locate a leak.

 

A friend stopped in at a shop to get his 1979 A model yesterday in Texas, dropped it to get both hog heads changed. All was good with everything else, till he picked it up that is. Could only build to 65 psi and would bleed off in 3 min. They finally had to replace 3 air lines and a splitter on the trans. He's thinking the guy who road tested it may not have been familiar with the trans.

 

Can you plug some workshop Air into the Wet tank?
A big long hose & keep It up around the 110-120 PSI mark. Should have better chance of hearing it at that pressure!!

 

Used to just drain the tanks and fill with freon and use a sniffer. Not supposed to do that anymore.

 

I see you haven't mentioned this yet, but worth a shot. I had a air leak and pulled my hair trying to find it, but I eventually did and was the fitting under the cab supply the air seat. Good luck.

 

Try one of these