Coolant coming out reservoir and WP leak

[Brock]

The bubble test will only show the compressor to be the issue if the compressor is building air. Make sure your cap is on and run your hose from your overflow tube. Problem is the PACCAR pressure relief caps are 13 psi caps so you need to let the system build over 13 psi before the bubble test would even start.

Let the truck run a while and get nice and hot, then if it starts bubbling pull the air output line off the compressor (line to air drier) and see if it still bubbles. Your compressor will constantly run with that line off but that's fine.

If when you warm up the motor and do the bubble test, it doesn't bubble.... Press the brakes a bunch to lower your air and get your compressor kicking in and then look to see if the bubbles are present.