Well, its not really falling on deaf ears. I'm going to change the fluid in the spring and then see what happens.
Also, to clarify, this gets to look like coffee. You can still see through it when its, say, a stream less than 3/4" deep.
But you should explain to all here how combustion gas at 500psi plus doesn't pressurize a 7 pound cap on the radiator. I'm willing to learn here, just don't see how that happens.
I will be the first to admit, your problem doesn't seem straightforward. From your initial post, "Anti-freeze put in, cam broke in. Took car around the block and parked it. 6 months later (or maybe immediately) the stuff is the color of strong strong coffee." From this if you break in a cam like I do (20 minutes), breaking in the cam, a trip around the block, and some miscellaneous time, you have probably, what, about 30 minutes total on the engine? That doesn't sound like a lot of run time to develop your problem. But you have to start somewhere and an antifreeze check eliminates both combustion gasses and oil contamination and could prevent you from wasting a coolant repalcement. Can a head gasket leak and not lift the radiator cap? No. But a slight leak just gets vented.
