The 855 Big Cam 1 in my road tractor has me pulling out my hair. It is loosing about one gallon of antifreeze to 500 miles. No external leaks, no antifreeze in the oil, no compression in the radiator, no vapor from the breather or grey snot in the valve covers. I pressurized the after cooler to 15# and after 2 days no drips or signs at all in the intake. Pressurized the engine to 10# and no leaks after 3 days. Spin it with the starter with both manifolds off and no signs of any moisture. I plan to warm it up with both manifolds off today and see what happens. About all that is left is an injector cup. Any other thoughts?