2022 Freightliner M2 106 - Air Brakes Slow to Build Pressure

Question

Lately my M2 is taking forever to get up to 120 psi. Used to take maybe 2 minutes from empty, now it's taking 5 or 6. I also hear the air dryer purging every 30 seconds while I'm driving.

I've listened for leaks around the wheel ends and the main tanks and don't hear any audible hissing when the truck is off. The governor was replaced last month by a mobile tech but it didn't seem to help much.

RustBeltRandy · Answer

✅ Confirmed fix: Found a massive leak in the 'signal' line going to the fan clutch. It's a small plastic air line that had rubbed against the shroud. It was leaking enough air to keep the compressor running but not enough to be easily heard over engine noise.

GarageGuyDave · Answer

Check the discharge line from the compressor to the air dryer. Those braided lines often get carboned up inside, especially if the compressor is starting to pass a little oil. It restricts the airflow and makes the compressor work much harder.

2022 Freightliner M2 106 - Air Brakes Slow to Build Pressure

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