YAMAHA UPPER BASE GASKET 67C-15312-00

Function and technical context

The upper base gasket is a critical component that seals the connection between the cylinder head and engine block on Yamaha outboard engines. This piece guarantees the tightness of the cooling circuit, preventing fresh or salt water from leaking into the engine. Its degradation compromises the integrity of the cooling system, which can cause accelerated overheating, internal corrosion and water entry into the cylinders and crankcase. Given constant exposure to thermal cycling and pressure changes, this gasket experiences progressive wear that requires periodic monitoring.

When to replace this part?

Symptoms of deterioration of this gasket include visible coolant leaks under the cylinder head, loss of engine power without apparent cause, and presence of water in the engine oil. Although there is no fixed replacement interval, it is recommended to inspect this gasket at each seasonal inspection and replace it preventively during cylinder head work or when any sign of leakage is detected. Changing the gasket before it fails completely prevents extensive repairs and unexpected downtime in the water.

Equivalent manufacturer part numbers