The air pop off sound that you hear after shutdown (usually some 5-15 mins after) is the air pressure regulator valve ("the air governor"). Normal and one of my favourite sounds the truck makes.
All these sounds my truck doesn't make - I feel like I'm missing out
@Gypsyman recently noticed an air system sound that may be attributed to air equalization between the storage tanks after shutdown, making a periodic hiss per
@rustystud .
As far as I noticed my truck makes all these sounds while it's running:
- Compressor knock while engaged - alarmed my dad one time when he thought there was something knocking inside the engine, but my M35A3 isn't the only one to make this noise when the compressor is charging the system
- Air dryer popping off air when compressor cuts out (M35A3s came with air dryers for the CTIS)
- Quiet hiss when releasing brake pedal
- Hiss when steering the truck (when equipped with air-assisted steering cylinder)
- Short hiss when actuating front axle drive using the dashboard switch
When the truck is shut off and I'm draining the tanks I hear a vibrating sound coming from the air system when the tanks are nearly empty - kinda sounds like a vibrating low guitar string. The noise goes away when the tanks are completely empty.
Granted my truck has a newer Cat 3116 and some other air system components that the A2 didn't come with.
