Continuous air leak from air dryer purge valve

Had a similar problem,turned out the housing had a hairline crack. Only way I found it was fueling on a rainy day.

 

Follow the small line out of dryer and find at other end of that air line the ck. valve that lets purge valve release air thats left over from inside air compressor it will unscrew from main air line after small line is off

 

I've got a wabco dryer as well had the same problem finally got to the point where it would purge constantly my fix was finally getting frustrated one night and smacking the air dryer with a hammer and it broke the pop off valve out. $300 and a new air dryer later problem was solved. I've got to the point where the truck gets a new air dryer every year they're fairly cheap beats the hell out of dealing with that problem specially in the winter when it's a whopping 2 above and spending 20 minutes bypassing the air dryer it's not fun in 4 inches of snow...don't ask me how i know.

 

You'll usually run into a plumbing nightmare when switching air dryers. I was going to upgrade to a bendix but would've had to change a lot of plumbing and said screw it the 300 junk wabco is fine. I don't worry much about it anymore. I've bypassed it a time or 2 which isn't illegal just a royal PITA draining the air tanks every time you stop. Water builds up quite quickly when you don't have the dryer. I left mine bypassed for about 2 weeks last winter while I waited for a new dryer to show up. One thing to never do is have a wabco rebuilt. The kit is about the same as a new dryer (least for mine) And the rebuilt ones last about 6 months.

 

GOOD #### $2000?!?!?!?! I'd be asking them if that air dryer was made of gold. Getting filters unstuck I always used a good quality chain wrench not a cheap TSC $30 wrench I've got a lifetime warranty snap on wrench it didn't come cheap but it's worth the money for stubborn filters. I've got a set of big channel locks I've used as well for stubborn filters as well when a chain wrench fails. With the cost of the new dual cartridge dryer I'd say you could probably replumb the truck and move the dryer cheaper. Like I said I've got a cheap dryer and it's easier to just replace it as opposed to messing with replumbing the system, and mounting the dryer in a different location (my dryer sits right in front of the battery box on my pete I'd have to move it somewhere under the bunk more than likely).