115 Mercury Outboard Powerhead Pull and Teardown - Why Does it Knock?

This Mercury 115 HP, 4 cylinder, 2 stroke engine has developed a very audible knock that seems the worst at idle. The engine runs fine otherwise and has been running like this for a while, except that the noise is increasing. Diagnostic work has been done to rule out as much as possible, so the time has come to remove the powerhead and disassemble it completely to find the cause of the noise. 00:20 What is the noise? 00:30 What has been done and what is the plan? 02:05 Start Powerhead Removal - Disconnect cables, hoses and electrical 03:55 Remove Lower Cowl 04:10 Remove Shift and Throttle 04:36 Remove External Electrical Power and Grounds 05:55 Remove Powerhead Studs and Hoist Powerhead 09:25 Remove Airbox & Oil Tank & Bleed Hoses 13:25 Remove Intake Manifolds and Reed Blocks 15:30 Remove Flywheel and Stator 16:30 View into Crankcase at Bottom of Pistons 17:00 Remove Hoses and Wires 19:30 Remove Starter / Coils / Ignition Wiring 24:10 Remove Exhaust Cover and Inspect through ports 28:18 Remove Cylinder Top Cover 30:00 Remove Oil Pump 31:40 Remove Lower Main Bearing Seal Housing 33:30 Remove Lower Crankcase Housing 37:35 Remove Crankshaft, Rods, Pistons as Assembly 39:00 Inspect Pistons and Cylinders DISCLAIMER: In my videos and written or text comments, I provide demonstrations, suggestions, and opinions on techniques, methods, and materials for various projects. While I try to be accurate, there are no guarantees, expressed or implied, that my information is correct and will work for you. If you wish to use any of this information, you must check and verify that it is appropriate for your use - use it at your risk. Do-it-yourself projects are variable and there are risks in conducting them. © 2024 Dan5tech LLC