27-858524 Mercury MerCruiser Water Pump Gasket | Genuine Quicksilver OEM Part

🔧 Product Description

Genuine Quicksilver Water Pump Gasket - Part Number: 27-858524

A genuine Quicksilver water pump gasket used in selected MerCruiser MC-1, R, MR and Alpha One sterndrive water pump assemblies, plus selected Mercury / Mariner outboard lower-unit water pump applications. This gasket seals the water pump housing / face plate area and is an important replacement component during impeller, water pump housing or lower-unit service.

⚙️ Key Features

• Genuine Quicksilver OEM water pump gasket

• Correct Mercury part number 27-858524

• Used in MC-1, R, MR and Alpha One drive-mounted water pump assemblies

• Also used across selected Mercury / Mariner outboard lower-unit water pumps

• Replaces multiple earlier Mercury water pump gasket references

🔄 Supersession & Cross Reference

OEM Supersession Chain:

• 27-858524 → Supersedes 27-85609B1

• 27-85609B1 → Supersedes 27-856091

• 27-856091 → Supersedes 27-85609

• 27-85609 → Related to / replaces 27-32434 and 27-30604 where specified

OEM / Related Numbers:

• 27-858524

• 858524

• 27858524

• 27-85609B1

• 85609B1

• 27-856091

• 856091

• 27-85609

• 85609

• 27-32434

• 32434

• 27-30604

• 30604

Aftermarket / Verified Equivalents:

• Sierra: 18-2915

• GLM: 31020

• Mallory: 9-60035

• EMP: 27-00672

• MC47-27-32434 related aftermarket reference

🚤 Compatibility

Commonly used on:

• MerCruiser MC-1 / R / MR / Alpha One drive-mounted water pump assemblies

• MerCruiser Alpha One-SS water pump applications

• Mercury / Mariner lower-unit water pump assemblies where 27-858524 is specified

Typically suits:

• Drive / transom models:

• MerCruiser MC-1 with flush screw - serial 2495186 to 2763441

• MerCruiser MC-1 without flush screw - serial 2763442 to 6854392

• MerCruiser MR / Alpha One - serial 6854393 to 0D469858

• MerCruiser R / MR / Alpha One Sterndrive - 1983-1990, serial 6225577 to 0F386995

• MerCruiser R / MR / Alpha One Transom Assembly - 1983-1990, serial 6216687 to 0F386995

• MerCruiser 1970-2006 MC-1, R / MR / Alpha One and Alpha One-SS water pump applications where this gasket is specified

• Mercury / Mariner outboard models:

• Mercury 4-cylinder 75HP - 80HP outboards, 1970-1980 / 1982-2006 application range where 27-858524 is specified

• Mercury 6-cylinder 90HP - 115HP outboards, 1970-1980 / 1982-2006 application range where 27-858524 is specified

• Mercury V6 135HP - 220HP outboards, 1970-1980 / 1982-2006 application range where 27-858524 is specified

• Mercury 110 Jet 2.5L - serial 1B690542 and up

• Mercury 140 Jet - serial 0G960500 to 0T178499

• Mercury 150 Pro XS 2.5L - serial 1B690542 and up

• Mercury 175 Pro XS 2.5L - serial 1B516339 and up

• Drive Type: MerCruiser MC-1 / R / MR / Alpha One / Alpha One-SS

• Engine Type: Mercury / Mariner outboard and MerCruiser sterndrive water pump applications

• System Type: Lower-unit / drive-mounted water pump gasket

🔌 Function

The gasket seals the water pump housing and face plate area so the impeller can draw and pressurise cooling water without leakage or pressure loss.

Common signs of failure:

• Weak tell-tale or reduced water pressure

• Engine overheating after water pump service

• Water pump housing leakage

• Gasket torn, crushed or missing during impeller replacement

• Poor cooling despite a new impeller

📦 Condition

• Genuine Quicksilver part

• Brand new

• Supplied in original or equivalent packaging