821354A2 Water Pump Impeller Kit for Mercury Mariner 25 30 40 50 HP 4-Stroke
821354A2 Water Pump Impeller Kit for Mercury Mariner 25 30 40 50 HP 4-Stroke
Product Overview
Water pump impeller kit for Mercury and Mariner 25, 30, 40 and 50 HP four-stroke outboards. It replaces Mercury 821354A2 and 821354A1, and crosses to Sierra 18-4531. The kit carries the impeller, the stainless wear plate and every seal and gasket between the pump housing and the gearcase, so the whole water pump is renewed in one job rather than piece by piece. On these small four-strokes the impeller is the only thing moving coolant, and a vane that has taken a set from a season of dry storage will not recover, it just pumps less and less until the overheat horn comes on at planing speed.
Two cylinder 30 and 40 HP, three cylinder 40 and 50 HP and the 50 HP Bigfoot all use the same pump cartridge, which is why one kit number covers the whole 25 to 50 HP range.
Specifications & Attributes
| Specification | Detail |
|---|---|
| Condition | New / New with tags |
| Type | Outboard Water Pump Impeller Repair Kit |
| Engine Family | Mercury and Mariner four-stroke outboards |
| Horsepower | 25 HP, 30 HP, 40 HP, 50 HP |
| Cylinders | 2 cylinder 30-40 HP, 3 cylinder 40-50 HP, 50 HP Bigfoot |
| Kit Components | Impeller, wear plate, 2 seals, 2 gaskets, washer, drive key |
| Packaging Size | 150 x 100 x 50 mm (5.9 x 3.9 x 2.0 in) |
OEM Cross Reference
| Brand | OEM Part Numbers |
|---|---|
| Mercury | 821354A2 (also listed as 47-821354A2) |
| Mercury | 821354A1 (also listed as 47-821354A1) |
| Sierra | 18-4531 |
| Sierra | 18-3057 impeller |
| Sierra | 18-4577 wear plate |
Compatible Engines
| Outboard | Cylinders | Stroke | Kit Fits |
|---|---|---|---|
| Mercury 25 HP | 2 | 4-stroke | Yes |
| Mercury 30 HP | 2 | 4-stroke | Yes |
| Mercury 40 HP | 2 or 3 | 4-stroke | Yes |
| Mercury 50 HP | 3 | 4-stroke | Yes |
| Mercury 50 HP Bigfoot | 3 | 4-stroke | Yes |
| Mariner 25 HP | 2 | 4-stroke | Yes |
| Mariner 30 HP | 2 | 4-stroke | Yes |
| Mariner 40 HP | 2 or 3 | 4-stroke | Yes |
| Mariner 50 HP | 3 | 4-stroke | Yes |
What's Included
| Component | Size / Note | Qty | Part Number |
|---|---|---|---|
| Impeller | 7 vane, keyed hub | 1 | 47-85089-3 / 47-85089-10 |
| Wear plate, stainless | Under the impeller | 1 | 821354-2 |
| Seal, short | 1 3/4 in | 1 | Not published |
| Seal, long | 2 1/4 in | 1 | Not published |
| Washer | Pump housing | 2 | Not published |
| Gasket, upper water pump | Housing to plate | 1 | Not published |
| Gasket, lower water pump | Plate to gearcase | 1 | Not published |
| Drive key | Impeller to shaft | 1 | Not published |
Condition & Warranty
| Item | Detail |
|---|---|
| Condition | New / New with tags |
| Warranty | 3 Year |
| Packaging | Sealed retail packaging |
Before You Buy
- Read the serial plate on the transom bracket, this kit is the four-stroke 25 to 50 HP pump and the two-stroke pumps use a different kit
- Check the 50 HP Bigfoot, it shares this impeller but has a longer gearcase than the standard 50
- Fit a new drive key every time, a worn key rounds off and the impeller stops turning
- Coat the impeller with a little liquid soap and turn the shaft clockwise as you push the housing down
- Run the engine on muffs before the first trip and watch for a strong telltale
- 30-Day Easy Returns
- Free Worldwide Shipping
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Boat Owners' Review
Before You Buy
Frequently Asked Questions
What is your refund policy?
We offer a 14-day hassle-free return on all products. Items must be unused and in original packaging. Every XRmarine part is also covered by our 1-year warranty against manufacturing defects. If something is not right, email us at info@xrmarineparts.com — replacement or full refund, your choice.
See our full Refund Policy for complete details.
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See our full Shipping Policy.
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