Air Leaks: Finding and Fixing Compressed Air Loss on a Truck
Air leaks drain your tanks overnight and trigger low-air warnings. We cover how to find them fast without guesswork.
Why air leaks matter
An air leak drops tank pressure, triggers the low-air warning and spring brake application, and can leave a truck unable to move — or unable to stop. A leak that drains the tanks overnight is annoying; a leak under the cab while driving is a roadside emergency. We find them by isolating the system, not by spraying the whole truck.
How we find a leak
We build the system to cut-out pressure, shut the truck off, and listen — then isolate by closing the tractor and trailer protection valves to separate tractor vs. trailer. A soapy-water check at fittings, valves, the compressor unloader, air dryer, and gladhand seals pinpoints the source. For hidden leaks we use an ultrasonic detector. The goal is to find the one leaking fitting, not re-pipe the whole system.
Common leak sources
The usual suspects are the air dryer purge valve (failed, leaks after cutout), gladhand seals and gladhand locks, the compressor unloader, brass fittings at tanks and valves, air bag leveling valves, and the spring brake chambers. A dryer that hisses constantly after cutout is the most common single cause of overnight drain.
Our mobile diesel technicians carry the tools and parts to diagnose and fix this on the shoulder or at your yard — 24/7/365 across Colorado, Wyoming, and Texas.
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