Scott, after a ride of 100/200 miles I find that I have to add 4 to 5 quarts of coolant, I don't see any leakage other than at the overflow so I am thinking that what a local radiator man told me may work. That is before installing a new radiator to try the 7# cap and see if that helps
That is a lot of coolant to lose without a trace. Maybe install a catch can on the overflow tube and see what you get? Otherwise it could be internal......is it missing or fouling any plugs? Oil look OK?
The cap is new and the way it seats on the radiator looks good. I had figured on just going ahead and replacing the radiator but the radiator guy suggested trying the higher pressure on the cap, so if the radiator goes that is what is needed. Oil looks good, tailpipe is dry. Trying a catch can sounds like a good idea to try, it may prove where the coolant is going