UPPER ENGINE BASE GASKET 27-16717M

Function and technical context

This upper engine base gasket constitutes a critical structural sealing element in Mercury two-stroke engines, particularly the 55 hp units. It is located between the cylinder head and the engine block, acting as a sealing barrier that prevents the escape of coolant and maintains the integrity of the fresh water cooling circuit. Its correct operation is essential to prevent the penetration of water into the combustion chambers, the loss of pressure in the cooling ducts and the progressive overheating of the propeller during navigation in salt or fresh water.

When to replace this part?

Engine base gaskets degrade due to repeated thermal cycles, chemical erosion of the coolant and prolonged compression, manifesting with symptoms such as visible loss of coolant, presence of water in the engine oil or increased block temperature. It is recommended to inspect this gasket during each seasonal maintenance and replace it preventively every 5 to 7 years of regular use or after major interventions on the cylinder head, thus avoiding costly breakdowns in navigation and prolonging the useful life of the engine.

Equivalent manufacturer part numbers