Water Pump Repair Kit Without Housing for Yamaha T25, F30 and F40 4-Stroke Outboards – Replaces 66T-W0078-00-00
Water Pump Repair Kit Without Housing for Yamaha T25, F30 and F40 4-Stroke Outboards – Replaces 66T-W0078-00-00 is backordered and will ship as soon as it is back in stock.
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Water Pump Repair Kit Without Housing for Yamaha T25, F30 and F40 4...
Water Pump Repair Kit Without Housing for Yamaha T25, F30 and F40 4-Stroke Outboards – Replaces 66T-W0078-00-00 is backordered and will ship as soon as it is back in stock.
Product Details
This water pump repair kit without housing is designed for selected Yamaha T25, F30 and F40 4-stroke outboard applications. It replaces the Yamaha water pump repair kit reference 66T-W0078-00-00 and supplies the principal wear components needed to service the water pump and restore dependable cooling-system operation.
This is an aftermarket replacement kit. It is supplied without the complete water pump housing; reuse the serviceable original housing or replace it separately when required. A catalog reference associated with this application is Sierra 18-3440.
- Water pump repair kit for selected Yamaha 25–40 hp 4-stroke outboards.
- Includes the impeller, wear plate, insert cup, gaskets, seals, key and fasteners shown below.
- Does not include the complete water pump housing.
- Verify the exact engine model, year and serial-number range before ordering.
Part Number References
Use these references when comparing the kit with your original part and service information.
| Brand or Source | Part Number | Application |
|---|---|---|
| Yamaha | 66T-W0078-00-00 | Water pump repair kit without housing |
| Sierra catalog reference | 18-3440 | Water pump kit without housing reference |
Engine & Model Compatibility
The catalog relationship read for this repair-kit family identifies the following Yamaha 4-stroke applications. Model designations, shaft configurations and serial-number ranges can affect fitment, so compare your complete engine identification before installation.
| Brand | Model Family | Rated HP | Stroke | Catalog Years | Replacement Reference | Housing |
|---|---|---|---|---|---|---|
| Yamaha | T25 | 25 | 4-Stroke | 2001–2004 | 66T-W0078-00-00 | Without housing |
| Yamaha | F30 | 30 | 4-Stroke | 2001–2004 | 66T-W0078-00-00 | Without housing |
| Yamaha | F40 | 40 | 4-Stroke | 2000–2004 | 66T-W0078-00-00 | Without housing |
Important: The application ranges above are catalog ranges, not a substitute for checking the model code and serial number on your engine. Do not rely on horsepower alone.
Technical Specs
- Product Type
- Outboard water pump repair kit without housing
- Engine Type
- Selected Yamaha 4-stroke outboard engines
- Horsepower Range
- 25–40 hp applications listed above
- Installation
- Replacement service part; installation should follow the applicable Yamaha service procedure
- Housing Included
- No. The complete water pump housing is not included.
What’s in the Box
- 1 x Pump Housing Cover — 63D-44312-00-00
- 1 x Insert Cup or Cartridge Insert — 63D-44322-00-00
- 1 x Wear Plate or Cartridge Outer Plate — 66T-44323-00-00
- 1 x O-Ring — 93210-59MG7-00
- 1 x Water Pump Gasket — 63D-44316-00-00
- 1 x Impeller — application reference 6H4-44352-00-00
- 1 x Woodruff Key — 90280-03M03-00
- 4 x Pump Housing Bolts — 90119-08M15-00
- 4 x Bolt Washers — 90209-08M02-00
- 1 x Water Seal or Seal Damper — 663-44366-00-00
Not included: complete water pump housing. Component descriptions may vary slightly by catalog terminology; compare the supplied parts with the removed components before assembly.
Installation Notes
- Disconnect the battery and make sure the engine is switched off, cool and securely supported.
- Remove the lower unit according to the applicable Yamaha service manual.
- Remove the existing water pump cover, impeller, wear plate, insert cup, gasket, seals and fasteners. Record the orientation of each component.
- Because this kit does not include the complete housing, inspect the original housing for scoring, cracks, distortion and excessive wear before reuse.
- Clean all mating surfaces thoroughly and remove old gasket material without damaging the sealing surfaces.
- Install the new gasket, insert cup, wear plate, seals and cover in the correct order and orientation.
- Make sure the Woodruff key is properly seated in the driveshaft keyway before installing the impeller.
- Lightly lubricate the impeller with a water-compatible lubricant and turn the driveshaft in the specified direction while fitting the impeller vanes into the housing.
- Install the bolts and washers and tighten them to the torque specified in the applicable Yamaha service manual.
- Reinstall the lower unit, ensuring that the water tube enters the pump outlet correctly.
- Run the engine with an appropriate flushing device before use and confirm a steady tell-tale water stream. Stop immediately if the engine overheats or water flow is abnormal.
Troubleshooting & FAQ
How do I know if the water pump needs service?
Common symptoms include a weak or intermittent tell-tale stream, an overheating alarm, higher-than-normal operating temperature or visible impeller damage. Always investigate the complete cooling system rather than replacing parts based on one symptom alone.
Does this kit include the water pump housing?
No. This is the repair-kit version without the complete housing. Inspect the original housing and replace it separately if it is worn, damaged or no longer provides the required sealing and clearance.
Which Yamaha engines are covered?
The catalog range associated with this repair-kit reference identifies Yamaha T25 models from 2001–2004, F30 models from 2001–2004 and F40 models from 2000–2004. Confirm the exact model code and serial number before ordering.
Is this kit for 2-stroke or 4-stroke engines?
This listing is intended for the Yamaha 4-stroke applications shown in the compatibility table. Do not use the kit on a 2-stroke engine solely because the horsepower rating appears similar.
Can I replace only the impeller?
A new impeller can sometimes be installed separately, but the wear plate, insert cup, gasket, O-ring, seal and fasteners also affect pump performance. Replacing the complete repair-kit contents is recommended when these parts show wear or when the pump is being serviced as preventive maintenance.
Is this an OEM Yamaha part?
No. This is an aftermarket replacement kit intended to match the listed application and replacement reference. Yamaha and other brand names and part numbers are used only to identify compatibility and reference parts.
What should I verify before purchase?
Verify the engine brand, model code, horsepower, stroke, year, shaft configuration and serial-number range. Also confirm that your existing housing is reusable because the complete housing is not included in this kit.
Safety & Important Information
- Use the applicable Yamaha service manual for removal, installation and torque specifications.
- Do not operate the engine without an adequate water supply or flushing device.
- Stop the engine immediately if the tell-tale stream is weak, the temperature rises unexpectedly or an overheating alarm occurs.
- Professional installation is recommended if you are not experienced with outboard lower-unit or water-pump service.
- Compare the supplied components with your original parts before installation; model and serial-number differences can change fitment.
About Sea Sierra
- Marine Replacement Parts — Service parts for common outboard maintenance and repair applications.
- Application-Focused Listings — Product information is organized around engine model and replacement-part references.
- Support for Installation Planning — Check the complete engine identification and applicable service information before ordering.
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