2011 kw t660 problem building air

2011 kw t660 only secondary tank is building air. if i swap the primary and secondary air lines on the air dryer then the primary tank will only build air. I think my issue is the air dryer. kenworth wants 550$ for a bendix k049199 is the number they gave me. part number on the air dryer is a bendix 500405 - still 550$ is there any aftermarket options with this air dryer? This is a spare truck and I really dont want to dish out 500+ for a truck that i really dont use

 

Sounds like you need a dryer. Affraid your stuck with what you have in front of you. Even if there was aftermarket available, I would stick with Bendix.

 

Genuine Bendix K049199 Ad-is Air Dryer Assembly for sale online | eBay

 

Usually when the dryer is bad, air is blowing out of the bottom purge valve. Is this what is happening?

 

No air is blowing from the purge valve. the air bags arent getting any air either and i can see they get supply straight from the dryer

 

The air governor maybe bad. They are cheap about $50

 

I thank these are an all in one unit. Have not had good luck trying to repair the all in one units.

 

I think you are right, that is why it is so expensive.

 

Tried the Bendix reman units, went back to new Bendix only. All of our Pete's and KW's use the 801266BXW.
Problem is usually the pressure protection valve stick in dryer. They are four PPV boots that can seen on drier, have tag that says do not adjust. Ones closest to purge valve are for Primary and secondary protection. Get a small awl or paper clip and some penetrating lube and spray in whole of boot and then push on piston. You will hear air go to secondary tank. This is not a fix, but a get you through the day or into the shop kind of fix.