Yamaha F90 Water Pump Impeller Replacement
A worn impeller on your 90 hp Yamaha F90 starves the engine of cooling water and can overheat the powerhead in minutes. Below is the water-pump kit we recommend, which F90 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 F90
2018 Yamaha 90 hp 4 stroke water pump parts you need
Replacing the Impeller on a 2018 Yamaha VF90 Outboard Motor
Tools Needed
- 12mm wrench or socket
- Flathead screwdriver
- Hammer
- Valve spring compressor tool (optional, but helpful)
- Cleaning supplies (rags, brushes, etc.)
Safety
- Always disconnect the negative battery cable before working on your outboard motor.
- Be cautious when using tools near the engine to prevent injury.
Steps
- Locate and remove the 12mm bolt at the bottom of the water pump housing.
- Remove the bolts on each side of the water pump foot, allowing it to fall down.
- Disconnect the small hose where water travels up through.
- Inspect the impeller; if it's similar to the one in the video (6E5-44352-01), proceed with removal.
- Remove the old impeller by using a tool to tap the cap off forcefully, being careful not to damage the nylon ring.
- Clean out any melted rubber or old impeller material from the housing and water passages.
- Install the new impeller, ensuring it's properly seated and secured.
- Reassemble the water pump foot and reconnect all hoses.
- Reinstall the 12mm bolt at the bottom of the water pump housing.
Tips
- Before purchasing a replacement impeller, ensure it matches your engine model (VF90 in this case).
- Be prepared for some force when removing the old impeller; using a valve spring compressor tool can help.
- Cleaning the motor thoroughly before and after the repair will help prevent future issues.
Which part do I need for my Yamaha F90?
For most F90 owners the kit above (89624) 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 (6)
| Part number | Description | Fits | |
|---|---|---|---|
| 18-3042 | Sierra 18-3042 | F90 | Find on Amazon → |
| 18-3409 | Sierra 18-3409 | F90 | Find on Amazon → |
| 18-3451 | Sierra 18-3451 | F90 | Find on Amazon → |
| 67F-44352-00-00 | 052 | F90TJRB, F90TLRB, F90TJRC and 7 more rigging variants (2003–2006) | Find on Amazon → |
| 8M6012801 | Mercury OEM 8M6012801 (replaces Sierra 18-3409) | F90 | Find on Amazon → |
| 8M6012802 | Mercury OEM 8M6012802 (replaces Sierra 18-3451) | F90 | 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 F90 (90 hp)?
The Yamaha F90 (90 hp) uses the impeller sold as Sierra 18-3042, plus its OEM and aftermarket cross-references (6 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 F90?
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 90 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 F90, 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 F90?
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 F70 water pump / impeller
- Yamaha F115 water pump / impeller
- All Yamaha water pump guides
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- Buying a boat? Check whether the asking price is fair
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