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Description

Johnson/Evinrude Water Pump Kit 439077 – Restore Proper Cooling & Protect Your Outboard

The Water Pump Kit is a complete OEM water pump repair kit with housing for select Johnson and Evinrude 2-stroke outboard engines.

The water pump is one of the most important components in the outboard cooling system. It pulls water through the gearcase and circulates it through the engine to remove heat generated during operation.

When the impeller, housing, seals, or related pump components become worn or damaged, water flow can decrease and engine temperature can rise quickly.

Common Signs of a Worn or Failing Water Pump

Possible symptoms may include:

• Weak telltale or water stream
• Intermittent cooling-water flow
• Engine overheating
• Overheat warning or alarm
• Reduced water pressure
• Steam from the exhaust or cooling outlet
• Higher-than-normal engine temperature
• Impeller blades that are cracked, stiff, or missing
• Scoring or grooves inside the water pump housing
• Cooling performance that gets worse at idle
• Engine overheating after sitting unused for an extended period

A weak telltale does not always mean the water pump is bad, but it should never be ignored. Blocked passages, thermostat problems, debris, and other cooling-system issues can cause similar symptoms.

Why the Water Pump Is So Important

Two-stroke outboards depend on a steady supply of cooling water to control cylinder, head, and exhaust temperatures.

If the water pump cannot supply adequate flow, overheating can cause:

• Head gasket failure
• Piston damage
• Cylinder scoring
• Warped cylinder heads
• Damaged seals
• Reduced engine life
• Complete powerhead failure

Replacing a questionable water pump is inexpensive compared with repairing an overheated powerhead.

Complete Kit With Housing

The OEM kit is supplied with the components required to service the applicable water pump configuration, including the housing and wedge-style impeller key components. This makes the kit especially useful during a complete lower-unit service when you want to refresh more than just the impeller.

Key Features & Benefits

• Complete Water Pump Kit – Includes the replacement pump housing
• Restores Cooling-Water Flow – Helps maintain proper circulation through the engine
• Helps Prevent Overheating – A properly functioning pump protects the powerhead from excessive heat
• Wedge-Key Pump Design – Intended for compatible Johnson/Evinrude small-gearcase applications
• Ideal for Preventative Maintenance – Excellent for routine lower-unit and cooling-system service
• Protects Expensive Engine Components – Proper cooling helps protect pistons, cylinders, gaskets, and seals

Common Applications

Used on select Johnson and Evinrude 2-stroke outboards from the late 1970s through the 1990s in the approximately 40–60 HP range, including many:

• 40 HP
• 45 HP
• 48 HP
• 50 HP
• 55 HP
• 60 HP

Horsepower alone should not be used to confirm fitment. Always verify:

• Engine model number
• Model year
• Gearcase configuration
• Existing water pump design
• Original OEM part number

When Should the Water Pump Be Replaced?

Water pump service should be considered when:

• The impeller is aged or its service history is unknown
• The engine has weak or inconsistent water flow
• The engine has experienced an overheating event
• The gearcase has been removed for other service
• The pump housing is scored or worn
• The impeller blades are cracked, hardened, distorted, or missing
• The boat has been stored for an extended period
• The engine is being prepared for heavy use or racing

Even if an impeller looks intact, rubber can harden with age and lose flexibility.

Inspect More Than Just the Impeller

Whenever servicing the water pump, inspect:

• Water pump housing
• Impeller
• Wear plate
• Seals and O-rings
• Water tube grommet
• Drive key
• Pump fasteners
• Water intake passages
• Driveshaft sealing area

Driveshaft oil retainers seals are not included with kit and must be ordered separately if replacement is needed.

Performance & Racing Considerations

For performance and race outboards, cooling-system reliability is especially important because the engine spends more time operating at elevated RPM and heavy load.

A marginal water pump that appears adequate during casual operation may not maintain enough flow when the engine is being pushed hard.

At Liquid Revolutions, we know that a water pump is inexpensive insurance compared with the cost of a damaged race powerhead. If the gearcase is already off and the pump history is unknown, replacing the complete pump assembly is often a smart preventative-maintenance decision.

Whether you’re maintaining a recreational Johnson/Evinrude outboard or preparing a performance engine for competition, the Complete Water Pump Kit helps restore reliable cooling water flow and protect the engine from overheating.

Always verify your engine model number, year, and gearcase configuration before ordering to confirm proper fitment.