cylinder head leak

[<RMS>]

My ’89 90hp Yamaha blew a pinhole through the cylinder head, pushing water out next to the sparkplug. Engine was running fine, started stumbling so I backed off the throttle and it stalled. Pulled the motor cover off and it started with some difficulty with water blowing out around the top plug or so it appeared. Limped home (10 minutes) at 1200rpm and pulled plugs. Top and middle were clean. Did a compression check, numbers were 90, 123, and 130 respectively. Last fall they were 130, 125, and 130. Pulled the cylinder head cover off and saw nothing untoward. When I pulled the head itself off I noticed the hole. I’m not sure how water got into cylinder number 2. The cylinder wasn’t as clean as #1 but water definitely got in. No obvious breach in gasket. Is it feasible for me to just purchase another cylinder head and reinstall with new gaskets? Any thoughts appreciated. Thanks, Bob

[<boats.net>]

You need to get running as soon as possible to get water out of engine the crank, bearings will rust. If cant get running then need to tear engine down and clean, If the cylinder with low compression is not scored and the cyl, piston looks ok then put a new head on and the compression will probably come back up

[<Ed McKenna>]

Just a friendly reminder to follow the torque specification when reinstalling the head screws.

[<RMS>]

Thanks for the comments, guys. I hosed the pistons/cylinders down with Corrosion X to forestall corrosion hopefully. I expect to have the engine back together this weekend. I have the Yamaha manual, which overall gives very little information, but it does have the torque specs. Bob