Yamaha F70 Water Pump Impeller Replacement
A worn impeller on your 70 hp Yamaha F70 starves the engine of cooling water and can overheat the powerhead in minutes. Below is the exact water-pump kit that fits this engine, a step-by-step video, and the parts you need to do the job yourself.
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Watch: how to replace it (step by step)
How to Replace Impeller – Yamaha Unknown Model
How To Replace A Water Pump Impeller Yamaha 70hp Outboard Motor
Tools Needed
- Flathead screwdriver
- 12mm socket wrench
- 14mm wrench
- Pliers
- Grease or anti-seize
Safety
- Ensure the engine is cool before starting.
- Be cautious when removing the lower unit to prevent it from falling.
Steps
- Tilt the motor up using the tilt button on the side of the engine.
- Remove the lower unit trim tab using a 12mm socket wrench.
- Unscrew the hidden bolt underneath the trim tab using a 12mm socket wrench.
- Remove the four bolts securing the water pump housing using a 14mm wrench.
- Lower the lower unit carefully, ensuring not to disconnect the speedo tube prematurely.
- Disconnect the speedo tube using pliers.
- Remove the water pump housing using a 12mm socket wrench.
- Pry out the old impeller using a flathead screwdriver, being careful not to lose the Woodruff key.
- Inspect the new impeller to ensure the fins are straight.
- Install the new impeller, aligning the notch with the Woodruff key.
- Grease the water pump housing and bolts.
- Reassemble the lower unit, ensuring the drive shaft is greased to prevent it from walking into the power head.
- Reconnect the speedo tube and install the lower unit back onto the engine.
- Tighten all bolts, including the one under the trim tab, and install a new zinc if needed.
- Install the rubber grommet piece on the midsection.
Tips
- Grease the bolts or use anti-seize to ensure easy removal during the next service.
- Ensure the impeller fins are straight to maintain proper water flow.
- Grease the drive shaft to prevent it from walking into the power head.
Which part do I need for my Yamaha F70?
For most F70 owners the kit above (89910) is the right choice — it includes the impeller plus the seals, gaskets and wear plate you should replace at the same time.
Frequently asked questions
What water pump impeller fits a Yamaha F70 (70 hp)?
The Yamaha F70 (70 hp) uses the impeller sold as 89910. Confirm the number against your engine's model code and year plate before ordering.
How often should I replace the impeller on a Yamaha F70?
Replace the water pump impeller every 1–3 years or roughly every 200–300 running hours, whichever comes first — and sooner if you run in silty, sandy or shallow water where debris wears the vanes faster.
What are the symptoms of a failing impeller on a 70 hp Yamaha?
A weak or missing telltale (pee) stream, engine temperature climbing above normal, or an overheat alarm are the classic warning signs. A worn impeller can overheat and damage the powerhead within minutes, so don't delay the job.
Do I need the full water pump kit or just the impeller?
For the F70, fit the complete kit. The seals, O-rings, gasket and wear plate age alongside the impeller, and replacing them together is the reliable, do-it-once job.
How long does a water pump job take on a Yamaha F70?
For a competent DIYer it's typically a 1–2 hour job of medium difficulty. The step-by-step video above covers every step for this engine.
Related guides
- Yamaha F25 water pump / impeller
- Yamaha F50 water pump / impeller
- Yamaha F90 water pump / impeller
- Yamaha F115 water pump / impeller
- All Yamaha water pump guides
- Free Yamaha F70 boat valuation
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