I have what I think is a 1986 15 hp rude. It's down at the marina and I can't check the serial number now. This motor is new to me and I know nothing of the history, however it seems to run great. The pee stream is always cold, even running WOT.....I'm assuming maybe the thermostat has been removed? Or is this normal? I'm bringing the motor home tomorrow and can post the serial number for better ID of year. Thanks in advance for any comments......John