I just bought an old Searcs Gamefisher 15 (Sears model# 217-586350, s/n 18 362689). It's in good shape and starts and runs fine, however I'm not sure if the cooling system is working properly. When I start the motor, no cooling water flows from the port until the motor heats up. At temperature, it flows reasonably well, but not like I've seen with other motors. I let the motor run at half throttle for 15 minutes in a barrel and the cooling water never warmed beyond 120-130 (hot but it never burned). Is this normal? The motor has a thermostat, but checking or replacing it would require removing the cylinder head (making me assume this is not a regular maintenance item). I just want to make sure this is normal. 