Water Pump Impeller Kit – Fits Mercury/Mariner/Force 8-25 HP (Replaces 99157T2, 46-99157T2)

$27.95 $44.00

Shipping calculated at checkout.

Water Pump Impeller Kit – Fits Mercury/Mariner/Force 8-25 HP (Replaces 99157T2, 46-99157T2) is backordered and will ship as soon as it is back in stock.

Worry-free returns

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).

If you need to return an item, simply login to your account, view the order using the "Complete Orders" link under the My Account menu and click the Return Item(s) button. We'll notify you via e-mail of your refund once we've received and processed the returned item.

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 Water Pump Impeller Kit – Fits Mercury/Mariner/Force 8-25 HP Outboard Engines is a crucial replacement part for maintaining your engine's cooling system. It is designed for a precise fit on a wide range of Mercury, Mariner, and Force 8–25 HP 2-stroke outboard engines manufactured from 1984 to 2005, ensuring reliable performance and preventing engine overheating.

This kit serves as a direct interchange for Mercury part numbers 99157T2, 85098A2, and 99157A2, as well as Sierra 18-3214.

Installation Location: Mounts in the lower unit of the outboard engine.
Essential Components: Includes a durable neoprene impeller, wear plate, gasket, and the complete pump housing for a comprehensive service.
Warranty Protection: Comes with a 1-year warranty for peace of mind against manufacturing defects.

Part Number Matrix

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

Brand	Part Number	Superseded By	Notes
Mercury	99157T2		Current OEM part number.
Mercury	99157A2	99157T2
Mercury	85098A2	99157A2
Sierra	18-3214		Aftermarket cross-reference.

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Mercury/Mariner engines, this kit fits various 2-stroke models from 8 HP to 25 HP manufactured between 1984 and 2005.

For Force engines, this kit is compatible with 25 HP 2-stroke models from 1995 to 1998, specifically the H025201 and H025211 series.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Mercury	8, 9.9, 13.5, 15, 18, 20, 25	8–25 HP	2-Stroke	1984–2005	99157T2	Superseded 99157A2, 85098A2
Mariner	8, 9.9, 13.5, 15, 18, 20, 25	8–25 HP	2-Stroke	1984–2005	99157T2	Superseded 99157A2, 85089A2
Force	25	25 HP	2-Stroke	1995–1998	99157T2	Models H025201 / H025211 series

Technical Specs

Product Type: Water Pump Impeller Kit with Housing
Installation: Lower Unit
Fuel Type: Gasoline
Included Components: Neoprene impeller, wear plate, gasket, and pump housing
Warranty: 1 Year (from Marine-Parts eBay seller)

What’s in the Box

1 x Water Pump Kit with Housing (Replaces 99157T2 / 46-99157T2)
1 x Neoprene Impeller (Replaces 47-85089-3 / 47-85089-10)
1 x Wear Plate (Replaces 85083)
1 x Gasket (Replaces 27-993261)
1 x Pump Housing (Replaces 46-99157A02)

Installation Notes

Disconnect the battery and shift the outboard into the neutral position.
Remove the bolts securing the lower unit (gearcase) and carefully lower it from the engine.
Locate and unbolt the water pump housing, which sits atop the gearcase.
Remove the old housing, impeller, wear plate, and any gasket remnants.
Thoroughly clean all mating surfaces to ensure they are free of old gasket material and corrosion.
Install the new wear plate and gasket onto the gearcase.
Slide the new impeller onto the driveshaft and into the new housing, turning the driveshaft clockwise to seat the impeller vanes correctly.
Lightly lubricate the interior of the housing with marine grease.
Position the new housing assembly and tighten the bolts to the manufacturer's specified torque.
Carefully reinstall the lower unit, ensuring the driveshaft, water tube, and shift shaft are properly aligned.
Once secured, reconnect the battery and test the engine in water, confirming a steady water stream from the cooling system's tell-tale outlet.

Troubleshooting & FAQ

How do I know if my water pump is failing?

Common signs include an engine overheating alarm, a weak or non-existent stream of water from the tell-tale outlet, and discovering a cracked, brittle, or worn impeller during inspection.

What is the recommended replacement interval for this kit?

For optimal engine protection and to prevent overheating, boat owners should inspect the impeller annually and replace it every 1 to 2 years (or every 100-200 hours of use), whichever comes first. Frequency should increase in silty or saltwater environments.

Will this fit a 4-stroke engine model?

No, this particular water pump kit is engineered specifically for the 2-stroke Mercury, Mariner, and Force outboard models listed in the compatibility table. It is not compatible with 4-stroke engines.

Does this kit include the outer housing?

Yes, this is a complete water pump rebuild kit that includes the pump housing, neoprene impeller, wear plate, and the required gasket for a full replacement.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9001 certified facility, batch-inspected for consistency.

Shipping speed & cost?

We ship worldwide quickly—typical transit 5–15 days. Standard shipping is free; expedited options appear at checkout where available.

Warranty & returns?

Covered by a 1-year warranty against manufacturing defects under normal use. If issues arise, contact support with your order details. Returns are accepted within our standard window (unused & in original condition). See our 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 part, not an original equipment manufacturer (OEM) component.
Professional installation is strongly recommended for safety, proper function, and engine performance.

About Sea Sierra

Pro-Grade Standards — We supply marine parts engineered to OEM-level tolerances and rigorously tested for real-world conditions.
Fast Global Fulfillment — We offer free standard delivery to most regions with an average transit time of 5–15 days.
Manufacturer-Direct Value — By working directly with manufacturers, we provide fair pricing without compromising on materials or quality control.

Payment & Security

Payment methods

Your payment information is processed securely. We do not store credit card details nor have access to your credit card information.