Yamaha 300hp Outboard Rebuild

This Yamaha F300 outboard had unfortunately suffered valve failure. The loose head of the valve then caused serious damage to the engine. This highlights the importance of 1000hr maintenance - valve clearance adjustment. The engine was stripped down and suspicions were confirmed. The valve had caused damage to the cylinder head, valves, valve seats, valve guides, piston and cylinder wall.
The powerhead was removed and disassembled. The cylinder head received new valve guides, valve seats and all new exhaust valves in both heads as a preventative measure. A new piston and connected rod was installed. The block was bored out and a liner was fitted to eliminate the damage to the old cylinder wall. The engine was reassembled with new piston rings and full gasket set.
Despite the serious damage to this engine, AHS Marine was able to undertake a reliable repair and the engine was brought back to life, saving serious expense for a new unit.