Air purge valve starts leaking at 105 psi

I need to get into the truck repair business 1600 for an air dryer. I hope they changing the air compressor too for that price. You must be at freightliner

 

I have the same one on my '18 Cascadia. Mine took a dump in the first 50k miles. Same problems. Had to replace the whole thing. Another truck in the fleet has the same, and it's gone through 2 of them in the past 2 years. That style of dryer is junk.

 

when it leaks is it steady or does it pulsate?
If it pulsates, look toward a leak between the air Governor and the unloader.
If it’s steady look toward a leaking outlet check valve for the air drier

 

Hmm, my Cascadia has an AD-9 air dryer, less than $200 exchange.

 

If it's building air pressure, seems the compressor is ok. With a price for your air dryer that much, I would go somewhere else.

Here's some links might help.

Brake Air Compressor Troubleshooting - Simplified

Advanced Troubleshooting Guide for Air Brake Compressors*
PDFBendix Commercial Vehicle Systems › tr...

Good luck.

 

I would try to adjust governor, also I’ve had luck in the past, sticking a small screwdriver into valve and holding it closed for a few seconds, sometimes a few tries before it stays closed. Weak springs or clogged with dirt. Spray it out good also. Find a cheaper air drier, switch it over if you have to, that’s too much $$$ for future maintenance costs