Water Pump Housing Gasket – Fits Mercury/Mercruiser 30-300HP Outboard & Alpha One Gen 2 (Replaces 27-8172771)

$8.99

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Product Details

This aftermarket Water Pump Housing Gasket is designed for a wide range of Mercury and Mercruiser engines, including 30–300 HP outboard models (both 4-Stroke and DFI) and Alpha One Gen 2 sterndrives from 1991 and newer. It is a crucial component for maintaining the integrity of the cooling system.

It serves as a direct replacement for multiple part numbers, including Mercury/Quicksilver 27-8172771, Sierra 18-2566, GLM 30290, and Mallory 9-60023, ensuring broad interchangeability.

Installs in the upper position, seating between the water pump housing and the wear plate.
Constructed from a durable fiber/paper composite to ensure a reliable, long-lasting seal.
Engineered specifically for the demands of marine water pump cooling systems.

Part Number Matrix

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

Brand	Part Number	Notes
Mercury/Quicksilver	27-8172771	Supersedes 27-817277
Sierra	18-2566 / 18-2566-9
GLM	30290
Mallory	9-60023
Chrysler/Force/US Marine	62-1570 / 2881-1401

Engine & Model Compatibility

Confirm your engine model/year in the table below.

For Mercury and Mercruiser models, this gasket fits a broad range of outboards and the Alpha One Gen 2 sterndrive. Check your specific model and year for a guaranteed match.

Brand	Model	Rated HP	Stroke	Years	OEM Part No.	Notes
Mercury	30-40 CARB	30-40	4-Stroke	1998 and newer	27-8172771	3 cylinder models
Mercury	40-60 ITALY/BODENSEE	40-60	4-Stroke	1998 and newer	27-8172771
Mercury	40-60 EFI	40-60	4-Stroke	1998 and newer	27-8172771	4 cylinder models
Mercury	40-60 JET	40-60	Both	1998 and newer	27-8172771
Mercury	65-80 JET	65-80	Both	1998 and newer	27-8172771	3 & 4 cylinder models
Mercury	75-90	75-90	Both	1998 and newer	27-8172771	3 cylinder & 4-Stroke models
Mercury	75-115 EFI	75-115	4-Stroke	1998 and newer	27-8172771
Mercury	75-125 DFI	75-125	2-Stroke	1998 and newer	27-8172771	1.5L (3 cylinder) models
Mercury	100-125	100-125	4-Stroke	1998 and newer	27-8172771	4 cylinder models
Mercury	135-175 VERADO	135-175	4-Stroke	2004 and newer	27-8172771	4 cylinder models
Mercury	150	150	4-Stroke	2019 and newer	27-8172771	Non-Verado models
Mercury	200-300 EFI	200-300	Both	1998 and newer	27-8172771	3.0L models
Mercury	200-300 DFI	200-300	2-Stroke	1998 and newer	27-8172771	3.0L & 3.2L models
Mercury	200-400 VERADO	200-400	4-Stroke	2004 and newer	27-8172771	6 cylinder models
Mercury	225-250 PRO XS	225-250	2-Stroke	2006 and newer	27-8172771	3.0L DFI models
Mercury	225-250 SPORT XS	225-250	2-Stroke	2004 and newer	27-8172771
Mercury	2.5XS DFI	2.5L	2-Stroke	2000–2004	27-8172771	Racing model
Mercury	JP 3.0L DFI	-	2-Stroke	2000–2004	27-8172771	Jet propulsion models

Brand	Model	Years	OEM Part No.	Notes
Mercruiser	ALPHA ONE GEN II	1991 and newer	27-8172771	Used in water pump assembly

Technical Specs

Product Type: Water Pump Housing Gasket
Installation: Upper Position (between pump housing and wear plate)
Material: Fiber/Paper
Application: Marine Outboard & Sterndrive
Dimensions: 15.0" L x 13.0" W x 0.5" H
Warranty: Varies by manufacturer (OEM Mercury: 1 year)
Other Technical Attributes: For water pump cooling systems

What’s in the Box

1 x Water Pump Housing Gasket (27-8172771)

Installation Notes

Disconnect the battery and ensure the engine is off and cool.
Drain the gearcase by removing the upper and lower drain/fill screws.
Remove the lower unit (gearcase) from the engine assembly.
Unbolt and remove the water pump housing to access the old gasket.
Carefully lift the old upper gasket, noting its position relative to the wear plate.
Thoroughly clean both the wear plate and housing surfaces, ensuring they are free of old gasket material and debris.
Position the new gasket (part #27-8172771) correctly onto the wear plate.
Reinstall the water pump housing and torque the bolts to the manufacturer's recommended specification.
Reassemble the lower unit, reinstall it on the engine, and refill with fresh gear lube.
Once fully assembled, start the engine and verify that the cooling system is functioning correctly (e.g., a steady stream from the tell-tale).

Troubleshooting & FAQ

How do I know if this gasket fits my engine?

The best method is to match your old part number to the ones listed in our Part Number Matrix. Alternatively, you can use the detailed Engine & Model Compatibility tables to find your specific engine model and year.

Where exactly is this "upper" gasket installed?

This gasket is installed in the "upper" position of the water pump assembly. It creates a seal between the top of the stainless steel wear plate and the bottom of the main plastic water pump housing.

What are the signs of a failing water pump gasket?

Common signs include the engine overheating at idle or low speeds, a weak or non-existent water stream from the "tell-tale" outlet, or visible water leaks around the lower unit where the pump is housed.

Do I need to use sealant with this gasket?

Typically, these fiber gaskets are designed for dry installation. Applying sealant can sometimes cause the gasket to slip out of place during assembly. Always consult your engine's official service manual for the most accurate procedure.

What is the difference between part 27-817277 and 27-8172771?

Part number 27-8172771 is the direct supersession for 27-817277, as designated by the manufacturer. It is the current, correct replacement part for any application that called for the older number.

OEM vs. Aftermarket?

This listing is an aftermarket replacement (not OEM). Built to OEM-level specifications with comparable materials. Manufactured in an ISO 9002 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/specifications vs your original part. If anything differs—even if your model appears compatible—do not purchase.
This is an aftermarket replacement, not an OEM component.
Professional installation is recommended for safety and performance.

About Sea Sierra

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