Sep 22, 2026
Yamaha 15HP Water Pump & Cooling Parts | Impeller, Pump Kit & Thermostat
Yamaha 15HP cooling system parts including water pump impeller, complete water pump kit, housing, plate, gasket, thermostat, water tube and seals.
Yamaha 15HP Water Pump & Cooling System Parts
The cooling system is critical to the service life of any outboard motor.
Unlike automotive engines, outboard motors draw cooling water directly from the surrounding water.
The water pump circulates this water through the engine to control operating temperature.
We supply Yamaha 15HP water pump and cooling system parts for routine maintenance and repair.
Main Cooling System Parts
Common parts include:
- Water Pump Impeller
- Water Pump Housing
- Water Pump Cup
- Water Pump Plate
- Water Pump Gasket
- Water Pump Repair Kit
- Impeller Key
- O-Ring
- Water Tube
- Thermostat
- Thermostat Gasket
- Water Jacket Gasket
- Cooling Passage Seals
Water Pump Impeller
The impeller is one of the most frequently replaced Yamaha outboard maintenance parts.
Its flexible rubber blades rotate inside the water pump housing and create the water flow needed to cool the engine.
A damaged impeller may cause:
- Weak tell-tale water flow
- Engine overheating
- High engine temperature
- Reduced cooling performance
- Serious powerhead damage
The impeller should be inspected periodically even when the engine appears to operate normally.
Complete Water Pump Kit
A water pump kit may contain:
- Impeller
- Housing
- Cup
- Wear plate
- Gasket
- O-ring
- Key
- Sealing components
If the housing or wear plate is already worn, replacing only the impeller may not fully restore water pump performance.
In this situation, replacing the complete water pump repair kit may be more appropriate.
Thermostat
The thermostat regulates engine temperature by controlling cooling water flow.
A thermostat stuck closed may cause:
- Overheating
- High engine temperature
A thermostat stuck open may cause:
- Engine running too cool
- Poor operating efficiency
Water Tube
The water tube carries cooling water from the water pump to the powerhead.
Problems may result from:
- Corrosion
- Blockage
- Incorrect installation
- Seal damage
Signs of Cooling System Problems
Check the cooling system when you notice:
- Weak cooling water outlet
- No water from tell-tale
- Engine overheating
- Temperature alarm
- Reduced engine power
- Steam around the engine
- Damaged impeller blades
Preventive Maintenance
Regular water pump maintenance is especially important for engines used in:
- Saltwater
- Sandy water
- Shallow water
- Commercial fishing
- High operating hours
After saltwater use, flushing the cooling system with fresh water can help reduce salt deposits and corrosion.
Yamaha 15HP Water Pump Parts Supplier
We provide impellers, repair kits and cooling components for Yamaha 15HP outboard motors.
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