losing coolant in an sp135

[gmkahn]

I'm losing coolant in my sp135. Pressure test shows everything's fine. Checked the heat exchanger - fine too. I've replaced the radiator cap twice - this one's tighter than . . . anyway, it's tight. Losing about 1/2 gallon per hour at 1700 rpms. Any tips? Should I try something like K-Seal?

 

[CHARLIE W]

Do not use sealant in your coolant. Is antifreeze in pan under engine ? Check circulating pump on front of engine for leaks