Water Pump Impeller Kit – Fits Mercury/Force 25-50 HP (Replaces 47-8508910, 47-850893, 47-8M0027792)

$21.66 $34.00

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Water Pump Impeller Kit – Fits Mercury/Force 25-50 HP (Replaces 47-8508910, 47-850893, 47-8M0027792) is backordered and will ship as soon as it is back in stock.

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You may return most new, unopened items within 7 days of delivery for a full refund. We'll also pay the return shipping costs if the return is a result of our error (you received an incorrect or defective item, etc.).

You should expect to receive your refund within four weeks of giving your package to the return shipper, however, in many cases you will receive a refund more quickly. This time period includes the transit time for us to receive your return from the shipper (5 to 10 business days), the time it takes us to process your return once we receive it (3 to 5 business days), and the time it takes your bank to process our refund request (5 to 10 business days).

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Delivery and Shipping

Free standard shipping on all orders under 1 KG

If you have any questions, feel free to email us at info@sierramarines.com, and we’ll get back to you within 20–36 hours.

Product Details

This aftermarket Water Pump Impeller Kit is designed for a wide range of Mercury Marine/Force 2-stroke and 4-stroke outboard motors from 25 HP to 50 HP (1994–2014) and select Chrysler/Force 25 HP, 40-50 HP, and 75 HP models. It ensures your engine’s cooling system operates efficiently by replacing a worn or damaged impeller.

It serves as a direct cross-reference for multiple part numbers, including Mercury 47-8508910, 47-8M0027792, and Sierra 18-3057, ensuring a precise fit and reliable performance.

Installation: Direct replacement requiring no modifications.
Material: Made with durable neoprene rubber and a metal alloy hub for longevity in marine environments.
Included Essentials: The kit contains the impeller and the required impeller key for a complete installation.

Part Number Matrix

Use this matrix to confirm equivalent references across OEM and aftermarket brands.

Brand	Part Number
Mercury Marine	47-85089-1
Mercury Marine	47-85089-3
Mercury Marine	47-85089-10
Mercury Marine	47-85089-20
Mercury Marine	47-8508910
Mercury Marine	47-850893
Mercury Marine	47-8M0024502
Mercury Marine	47-8M0027792
Sierra	18-3057
CEF Marine	500315
Mallory Marine	9-45303
QuickMariner	8508910

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Mercury/Mariner outboards, verify your engine's serial number or year range to ensure correct fitment. This impeller fits a broad range of 2-stroke and 4-stroke models from 18 HP to 50 HP.

Model	Rated HP	Stroke	Years	OEM Part No.
18 HP	18	2-Stroke	Serial# 5837437-UP	47-8508910
20 HP	20	2-Stroke	Serial# 6443973-UP	47-8508910
25 HP	25	2-Stroke	Serial# 5705532-UP	47-8508910
25XD, 25 Sea Pro	25	2-Stroke	Serial# 5705532-UP	47-8508910
25 HP (3 cyl)	25	2-Stroke	Serial# E268781-UP	47-8508910
25 HP	25	4-Stroke	1998–2006	47-8508910
30 HP Jet	30	2-Stroke	Serial# G590000-UP	47-8508910
30 HP (2 cyl)	30	2-Stroke	Serial# G053314-UP	47-8508910
30 HP	30	4-Stroke	1999–2006	47-8508910
40 HP (2 cyl)	40	2-Stroke	Serial# G053314-UP	47-8508910
40 HP (3 cyl)	40	2-Stroke	Serial# G531301-UP	47-8508910
40 HP	40	4-Stroke	Serial# G231123-G760299	47-8508910
40 HP	40	4-Stroke	Serial# G760300-T408999 (2:1 ratio)	47-8508910
40 HP	40	4-Stroke	1999–2007	47-8508910
45 HP Bodensee	45	4-Stroke	Serial# G231123-UP	47-8508910
45 HP	45	4-Stroke	1995–2000	47-8508910
50 HP (3 cyl)	50	2-Stroke	Serial# G590000-UP	47-8508910
50 HP	50	4-Stroke	Serial# G231123-UP	47-8508910
50 HP	50	4-Stroke	1995–2000	47-8508910

This part also fits select Force and Chrysler outboards. Check your serial number against the provided ranges to confirm compatibility.

Model	Rated HP	Stroke	Years	OEM Part No.	Notes
25 HP	25	2-Stroke	1996–1998	47-850893	Serial# E127700-E344999
40 HP	40	2-Stroke	1995–1999	47-850893	Serial# E093700-E369299
50 HP	50	2-Stroke	1995–1999	47-850893	Serial# E093700-E369299
75 HP	75	2-Stroke	1999	47-850893	Serial# E345000-UP

Technical Specs

Product Type: Water Pump Impeller Kit
Installation: Direct Replacement
Material: Neoprene Rubber with Metal Alloy Hub
Number of Blades: 6
Impeller Height: 12.6 mm (0.50 inches)
Overall Diameter: 73.8 mm (2.91 inches)
Hub Shaft Diameter: 16.0 mm (0.63 inch)
Weight: 40 g (1.41 oz)
Housing Color: Black
Other Technical Attributes: Includes impeller key #28-85119

What’s in the Box

1 x Water Pump Impeller (47-8508910)
1 x Impeller Key (28-85119)

Installation Notes

Disconnect the battery and remove the spark plug wires for safety.
Drain the gear lube from the lower unit.
Remove the mounting bolts securing the lower unit (gearcase) to the engine midsection.
Carefully separate the lower unit from the engine. You may need to disconnect a speedometer tube or shift linkage.
Locate and unbolt the water pump housing cover.
Note the rotational direction of the old impeller's blades before removing it.
Slide the old impeller off the driveshaft and remove the old impeller key.
Clean the pump housing, wear plate, and all mating surfaces thoroughly.
Install the new impeller key into the slot on the driveshaft.
Slide the new impeller onto the shaft while turning the driveshaft clockwise to bend the blades correctly.
Reassemble the pump housing, using new gaskets where required, and torque bolts to manufacturer specifications.
Reinstall the lower unit, refill with fresh gear lube, and test the engine's cooling stream.

Troubleshooting & FAQ

How do I find my engine's serial number?

The serial number is typically found on a metal plate or sticker on the transom mounting bracket of your outboard motor. It is essential for confirming exact part fitment.

What are the signs of a failing water pump impeller?

Common signs include the engine overheating at idle or low speeds, a weak or non-existent water stream from the "telltale" outlet, and a dry, cracked, or brittle appearance on the old impeller upon inspection.

How often should this impeller be replaced?

For preventative maintenance, it is recommended to replace your water pump impeller every 1–2 years or every 100–200 hours of operation, whichever comes first, especially if you operate in saltwater or sandy/silty conditions.

Can I install this part myself?

While installation is possible for those with mechanical experience and the correct tools, we recommend professional installation to ensure proper function and avoid potential engine damage.

Is there a difference in performance compared to the OEM part?

This aftermarket part is designed to meet or exceed OEM specifications for fit, form, and function. It provides comparable cooling performance and durability under normal operating conditions.

What is the difference between an OEM and an aftermarket part?

This listing is an aftermarket replacement (not OEM). It is built to OEM-level specifications with comparable materials. All parts are manufactured in an ISO 9002 facility and are batch-inspected for quality and consistency.

What are your shipping speed and cost?

We ship worldwide quickly—typical transit is 5–15 days. Standard shipping is free for most orders, with expedited options available at checkout where applicable.

What is the warranty and return policy?

This product is covered by a 1-year warranty against manufacturing defects under normal use. If you encounter an issue, please contact our support team with your order details. Returns are accepted within our standard window for unused items in their original condition. See our full policy page or reach out for instructions.

Safety & Important Info

Verify images and specifications against your original part. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement, not an OEM component. Brand names and part numbers are used for reference purposes only.
Professional installation is recommended for safety and performance. Improper installation can lead to engine damage.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and tested for real-world conditions.
Fast Global Fulfillment — Free standard delivery to most regions in 5–15 days, getting you back on the water faster.
Manufacturer-Direct Value — By working directly with manufacturers, we offer fair pricing without compromising on materials or quality control.

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