Water Pump Impeller Kit 47-89981Q1 89981T2 18-3239 for Mercury 4 4.5 6 7.5 9.8 HP Outboard with Face Plate Key O-Rings — United States Local Warehouse
Water Pump Impeller Kit 47-89981Q1 89981T2 18-3239 for Mercury 4 4.5 6 7.5 9.8 HP Outboard with Face Plate Key O-Rings — United States Local Warehouse
Product Overview
Water pump impeller kit part for Mercury 4 HP, 4.5 HP, 6 HP, 7.5 HP and 9.8 HP outboards, with an impeller insert of 0.456 inch (11.6 mm). It replaces 47-89981Q1, 89981Q1 and 89981T2 and crosses to Sierra 18-3239, and it ships as 1 x impeller, 1 x face plate, 1 x drive key, 1 x water guide tube and 3 x O-rings. Shipped from our United States local warehouse.
On the small Mercury pump the face plate wears with the blades, so a new impeller against a scored plate loses pressure the moment it runs. That is why the plate, the key, the guide tube and the three O-rings come in the same box.
It covers the 4 HP, 4.5 HP, 6 HP and 7.5 HP single and twin cylinder motors plus the 9.8 HP that Mercury badged as the 110, from the 1970s through the serial ranges listed below. Mercury built these motors and sold the same pump under the Mariner name, so the kit covers Mariner 4 HP to 9.8 HP motors of the same years.
Specifications
| Specification | Detail |
|---|---|
| Condition | New / New with tags |
| Type | Water pump impeller service kit |
| Impeller Insert Diameter | 0.456 inch (11.6 mm) |
| Kit Contents | Impeller, face plate, drive key, guide tube, 3 O-rings |
| Net Weight | 33 g |
| Horsepower Range | 4 HP to 9.8 HP |
| Country of Origin | Taiwan |
OEM Cross Reference
| Brand | Part Numbers |
|---|---|
| Mercury | 47-89981Q1, 89981Q1, 89981T2 |
| Mercury impeller | 47-89981, 47-65957, 47-39074, 465957 |
| Mercury face plate | 46895 |
| Mercury drive key | 8M0032835, 56655 |
| Mercury rubber part | 26-30526 |
| Mercury plastic part | 31792T |
| Mercury O-ring | 25-48171, 976994 |
| Sierra | 18-3239 |
Compatible Engines
| Horsepower | Cylinders | Fits |
|---|---|---|
| 4 HP | Single cylinder | Yes, by serial range |
| 4.5 HP | Two cylinder | Yes, by serial range |
| 6 HP | Single or two cylinder | Yes, overlaps the 6 HP ranges |
| 7.5 HP | Two cylinder | Yes, by serial range |
| 9.8 HP | Two cylinder | Yes, badge 110 |
| 110 (9.8 HP) | Two cylinder | Yes, same pump |
| Larger Mercury pumps | 4 cylinder | No, the insert diameter is bigger |
Serial Number Ranges
| Horsepower | Model Note | Serial Number Range |
|---|---|---|
| 4 HP | Single cylinder | 2498136 to 4107219 |
| 4 HP | Made in USA | 5595532 and up |
| 4.5 HP | Two cylinder | 4107220 to 5595531 |
| 4.5 HP | Two cylinder | 5595532 and up |
| 6 HP | Single cylinder | 1582403 to 1916138 |
| 6 HP | Single cylinder | 1916139 to 2193817 |
| 6 HP | Two cylinder | 2193818 to 2529894 |
| 6 HP | Two cylinder | 2385673 to 2387383 |
| 7.5 HP | Two cylinder | 2529895 to 4131609 |
| 7.5 HP | Two cylinder | 4131610 to 5226934 |
| 7.5 HP | Two cylinder | 5206550 and up |
| 110 (9.8 HP) | Two cylinder | 1865779 to 2196388 |
| 110 (9.8 HP) | Two cylinder | 2196389 to 3795657 |
| 110 (9.8 HP) | Two cylinder | 3795658 to 4126459 |
| 110 (9.8 HP) | Two cylinder | 4126460 to 5206549 |
| 9.8 HP | Two cylinder | 5206550 and up |
What's Included
| Component | Reference | Qty |
|---|---|---|
| Water pump impeller | 47-89981, 0.456 inch (11.6 mm) insert | 1 |
| Face plate | 46895, stainless | 1 |
| Drive key | 8M0032835, 56655 | 1 |
| Water guide tube | 31792T | 1 |
| O-ring | 25-48171, 976994 | 3 |
| Rubber seal | 26-30526 | 1 |
Why the Face Plate Comes in the Kit
| Old Face Plate Condition | What It Does to a New Impeller | Result |
|---|---|---|
| Smooth, no wear ring | Blades bed in normally | Full pressure from the first run |
| Light scoring | Blades lose a little tip clearance | Pressure down maybe 10 percent |
| Visible grooves | Blades wear into the grooves and tear | New impeller fails within a season |
| Plate polished shiny and convex | Clearance too large, water slips back | Overheat at low revs only |
| Plate corroded or pitted | Grit and corrosion chew the blades | Telltale weak from day one |
| Plate missing or wrong thickness | Housing sits wrong, blades bind | Housing and impeller both damaged |
Freshwater, Saltwater and the Small Mercury Pump
| Where the Boat Runs | Effect on the Kit Parts | What To Do |
|---|---|---|
| Freshwater lakes, seasonal use | Rubber sets over winter, plate lasts | Renew on the calendar, check the plate |
| Saltwater, trailer boat | Salt dries on the blades and the plate | Flush on muffs after every trip |
| Brackish river water | Silt packs the face plate face | Check the plate each season |
| Florida and Gulf use | Year round running, faster wear | Inspect at 100 hours |
| Northern states, stored frozen | Water freezing below 0 °C in the pump | Drain the pump at lay up |
| Motor run dry at the ramp | Blades burn in seconds | Never start without water |
Fitting Notes
| Step | Action |
|---|---|
| 1 | Check the impeller insert is 0.456 inch (11.6 mm), the larger Mercury pump uses a bigger shaft |
| 2 | Read the serial number and match it to the ranges in the table |
| 3 | Fit the new face plate from the kit, reusing the old one wastes the new impeller |
| 4 | Check the pump housing liner for deep grooves, a scored housing needs replacing too |
| 5 | Fold the blades in the direction of rotation and lubricate with glycerine only |
| 6 | Fit the drive key and the water guide tube before the housing goes down |
| 7 | Fit all three O-rings, a missing one weeps air and the pump loses prime |
| 8 | Run on muffs and check the telltale at idle, then again under load in the water |
Condition & Warranty
| Item | Detail |
|---|---|
| Condition | New / New with tags |
| Warranty | Standard |
| Packaging | Sealed retail packaging |
Shipping from United States
| Destination | Warehouse | Note |
|---|---|---|
| United States | United States local warehouse | Domestic delivery, no import duty |
| Canada | United States local warehouse | Customs may apply |
| US territories | United States local warehouse | Tracked shipping available |
Before You Buy
- Check the impeller insert is 0.456 inch (11.6 mm), the larger Mercury pump uses a bigger shaft
- Check the serial number against the ranges, the 6 HP was built in several overlapping blocks
- Fit the new face plate from the kit, do not reuse the old one
- Check the pump housing liner for deep grooves
- Fit all three O-rings and the water guide tube
- This is the pump kit, the housing, liner and gaskets are not included
- 30-Day Easy Returns
- Ships from our United States local warehouse
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