Yamaha F25 Water Pump Impeller Replacement
A worn impeller on your 25 hp Yamaha F25 starves the engine of cooling water and can overheat the powerhead in minutes. Below is the water-pump kit we recommend, which F25 variants it fits, 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 the water pump impeller on a Yamaha F25
How to replace the impeller on Yamaha 25hp outboard
Tools Needed
- 10mm wrench
- 12mm wrench
- Screwdriver
- Grease
- Steel wool
Safety
- Ensure the motor is cool before starting.
- Be careful when handling sharp or rusty parts.
Steps
- Remove the thermostat housing and spark plugs.
- Disconnect the gearbox by removing the four 10mm bolts.
- Slide the gearbox out and remove the impeller housing.
- Remove the old impeller and clean the housing.
- Grease the housing and the new impeller.
- Install the new impeller, ensuring the teeth bend in the correct direction.
- Reinstall the impeller housing and secure it with the four 10mm bolts.
- Reconnect the gearbox and secure it with the four 12mm bolts.
- Reinstall the thermostat housing and spark plugs.
Tips
- Remember the direction of the impeller teeth before removing the old impeller.
- Grease the impeller and housing to ensure smooth operation.
- Be patient when reconnecting the gearbox, as it may require some fiddling.
Which part do I need for my Yamaha F25?
For most F25 owners the kit above (89900) is the right choice — it includes the impeller plus the seals, gaskets and wear plate you should replace at the same time. Price tip: the aftermarket numbers are usually noticeably cheaper than the OEM-branded box — it is the same physical part. If you need an exact match, these compatible part numbers also fit:
Show all compatible part numbers (5)
| Part number | Description | Fits | |
|---|---|---|---|
| 18-3068 | Sierra 18-3068 | F25 | Find on Amazon → |
| 18-3432 | Sierra 18-3432 | F25 | Find on Amazon → |
| 18-3443 | Sierra 18-3443 | F25 | Find on Amazon → |
| 6H4-44352-02-00 | 052 | F25ELHW, F25ELRW, F25ESHW and 51 more rigging variants (1998–2006) | Find on Amazon → |
| 6L5-44352-00-00 | 052 | F25MSHB (2003–2003), F25MSHC (2004–2004), F25MSHD (2005–2005), F25MSH (2006–2006) | Find on Amazon → |
Many of these are the same physical part under different brand numbers (Sierra, GLM, Yamaha OEM). Build years are shown where our parts data has them. Where a variant has no years, only the model code is listed. Confirm the number against your engine plate before ordering.
Frequently asked questions
What water pump impeller fits a Yamaha F25 (25 hp)?
The Yamaha F25 (25 hp) uses the impeller sold as Sierra 18-3068, plus its OEM and aftermarket cross-references (5 compatible numbers are listed above). Confirm the number against your engine's model code and year plate before ordering.
How often should I replace the impeller on a Yamaha F25?
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 25 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 F25, 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 F25?
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 F50 water pump / impeller
- Yamaha F70 water pump / impeller
- Yamaha F90 water pump / impeller
- Yamaha F115 water pump / impeller
- All Yamaha water pump guides
- Free Yamaha F25 boat valuation
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