Honda BF40 Water Pump Impeller Replacement
A worn impeller on your 40 hp Honda BF40 starves the engine of cooling water and can overheat it in minutes. Below is the water-pump kit we recommend, which BF40 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 Honda BF40
Honda Outboard 40 hp How to disassemble and take apart the Water Pump Impeller A
Tools Needed
- Screwdriver
- Pry tool
- Compressed air can
Safety
- Ensure the engine is turned off and cool before starting.
- Wear safety glasses to protect your eyes from debris.
Steps
- Unscrew the four bolts holding the water pump impeller in place.
- Remove the metal inserts from each bolt and set them aside, ensuring not to lose them.
- Lift the impeller off the shaft.
- Undo the metal plate securing the old impeller and carefully remove it from the shaft.
- Slowly pry the impeller off, ensuring the gasket and any debris come off with it.
- Inspect the inside of the pipe for any obstructions or damage.
- Use compressed air to blow out any remaining debris or obstructions from the pipe.
Tips
- Be cautious when prying off the impeller to avoid damaging the gasket or the bearings.
- Ensure the new impeller is properly aligned with the groove before reinstalling it.
Which part do I need for my Honda BF40?
For most BF40 owners the part above (18-3248) is the right choice. 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 (7)
| Part number | Description | Fits | |
|---|---|---|---|
| 06193-ZV5-010 | Honda Water Pump Service Kit BF40A4 / BF50A4 (06193-ZV5-020 / 06193-ZV5-010) | BF40A4 | Find on Amazon → |
| 06193-ZV5-020 | Honda Water Pump Service Kit BF40A4 / BF50A4 (06193-ZV5-020 / 06193-ZV5-010) | BF40A4 | Find on Amazon → |
| 18-3282 | Impeller for Honda BF40A | BF40A, BF40D | Find on Amazon → |
| 19210-ZV5-003 | Honda Impeller BF35 / BF40 / BF45 / BF50 / BF60 (19210-ZV5-003) | BF40 | Find on Amazon → |
| 19233-ZV5-000 | Honda Water pump Gasket BF35AM BF40B / B2 / BX / A4 / D / DK2 / A / A1 / 2 / AX / AY BF45AM BF25D4 / DK2 / A / A1 / AX / A2 / A3 BF30D4 / K2 / A / A1 / AX / AZ / A3 BF50A4 / D / DK2 / A / A1 / A2 / AX | BF40B | Find on Amazon → |
| 19242-ZV5-000 | Honda Water pump Gasket BF20A / AX / A2 BF35AM BF40B / B2 / BX / A4 / D / DK2 / A / A1 / A2 / AX / A3 / AY BF45AM BF25D4 / DK2 / A / A1 / AX / A2 / A3 BF50A4 / D / DK2 / A / A1 / A2 / A3 / AY BF30D4 / | BF40B | Find on Amazon → |
| 90752-ZV5-003 | Honda Impeller Key BF35 / BF40 / BF45 / BF50 / BF60 (90752-ZV5-003) | BF40 | Find on Amazon → |
Many of these are the same physical part under different brand numbers. Build years are shown where our parts data has them. Where a variant has no years, only the model code is listed. Confirm against your engine plate before ordering.
Frequently asked questions
What water pump impeller fits a Honda BF40 (40 hp)?
The Honda BF40 uses the impeller sold as Sierra 18-3248, plus its OEM and aftermarket cross-references (7 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 Honda BF40?
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.
What are the symptoms of a failing impeller on a Honda BF40?
A weak or missing telltale stream, engine temperature climbing above normal, or an overheat alarm are the classic warning signs. A worn impeller can overheat and damage the engine within minutes, so don't delay the job.
Do I need the full water pump kit or just the impeller?
For the BF40, 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 Honda BF40?
For a competent DIYer it's typically a 1-2 hour job of medium difficulty. The step-by-step video above covers every step.
Related guides
- Honda BF5 water pump / impeller
- Honda BF225 water pump / impeller
- All Honda water pump guides
- Free Honda boat valuation
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