I noticed my new-to-me model year 2000 Yamaha F100 wasn't peeing out the back but wasn't running hot either. The owner's manual makes no reference to how the cooling system works or where it pees. So after limping back to shore I see there are two pee holes: upper rear that should pee out the back and lower front that pees forward just above the water line. To my surprise the upper rear is deliberately plugged with a screw. I took the cowl off to see the lines to both holes are intact. Warm cooling water comes out the lower front hole under good pressure.
My guess is the last guy that worked on the motor plugged the hole so he could run it in a test tank without peeing on the floor then forgot about it. The previous owner says he didn't know anything about it. Is there a valid reason to permanently plug a pee hole in this engine? The boat is in cool north Puget Sound waters so maybe the motor wasn't getting up to normal operating temp? The maintenance receipts I got with the boat make no mention of this. Thanks for your help.
My guess is the last guy that worked on the motor plugged the hole so he could run it in a test tank without peeing on the floor then forgot about it. The previous owner says he didn't know anything about it. Is there a valid reason to permanently plug a pee hole in this engine? The boat is in cool north Puget Sound waters so maybe the motor wasn't getting up to normal operating temp? The maintenance receipts I got with the boat make no mention of this. Thanks for your help.