Boat has chevy block, 211 hp, year 1990, rebuilt last year. Loosing coolant through radiator cap while engine runs at 130 degrees at 3000rpm. Thermostat opens at 160 degrees. I have attached a tube to the overflow fitting under the cap, so coolant collects in a bottle. Engine eventually overheats when about 2 quarts has been ejected from heat exchanger. Thermostat is new, no leaks, raw water is flowing. Cap is rated at 12 lbs, and is new. Should I try a higher pressure rated cap, or will that hurt the system?
