Nebster,
My problem was occurring when the engine air pressure reached 120 or higher like 140 on the dash gauge. This would happen at idle while stopped and no load or driving. I could walk around the left rear tag wheel and hear it pop,pop,pop at the air dryer filter. Then the top rear of the air compressor would psssssss air over the, what I now know to be, the overload valve. Once the engine was off, this overload valve would PSSS for a few more seconds until pressure lowered to ???120psi I think.
I have a Cat C15, and I've not seen a pop off valve for the progressive turbo's. Pop off valves on Turbo's blow off excessive pressure after maximum boost has been reached, or just before an upshift, but never under Jake braking.
My 2 cents
My problem was occurring when the engine air pressure reached 120 or higher like 140 on the dash gauge. This would happen at idle while stopped and no load or driving. I could walk around the left rear tag wheel and hear it pop,pop,pop at the air dryer filter. Then the top rear of the air compressor would psssssss air over the, what I now know to be, the overload valve. Once the engine was off, this overload valve would PSSS for a few more seconds until pressure lowered to ???120psi I think.
I have a Cat C15, and I've not seen a pop off valve for the progressive turbo's. Pop off valves on Turbo's blow off excessive pressure after maximum boost has been reached, or just before an upshift, but never under Jake braking.
My 2 cents

Dave, Karen, w/Buddy and Moose.
06' Newell #784
towing a 06' Featherlite enclosed trailer or
05' Featherlite stacker for toys and tools,
or a 21' F350

35' Packard 4 dr convertible
59' Nash Metropolitan
I like engines and wheels
Carpe Diem. Have Fun
Tomorrow is not guaranteed.