Exhaust Back Flow valve issue 2013 Maxxforce 11

When the air compressor is building air and the engine has warmed up, there is a noisy racket coming from the exhaust back flow valve area. When the air compressor cuts off, the noise is gone. Air pressure then falls from 135 to 118 psi in about 2 mins. Searched for air leak. Dealer says air compressor is good, should be, it’s new OEM. Replaced Air Control Valve (OEM) recently due to an air leak from its body. Sure hope this sounds familiar to someone!

 

It’s just past the turbo on the exhaust pipe. I found the noise is not coming from the exhaust back flow valve itself but in the areas I can hear it in the exhaust pipe. Just confusing that when the air compressor cuts off the noise goes away and I lose air pressure quickly to 115 psi. Probably have to take it in to the dealer for eval.