New Marine Water Pump O-Ring 3.500 Id 0.210 Width Compatible With 1970-1998 Mercury Mariner

WATER PUMP O-RING — MERCURY/MARINER/MERCRUISER 3.500 ID x 0.210 WIDTH:

MERCURY 4-CYLINDER OUTBOARD APPLICATIONS:
• Mercury 65 HP 4-Cyl 2-Stroke Outboard (1970-1971)
• Mercury 75 HP 4-Cyl 2.875 Bore Cross Flow 2-Stroke Outboard (1984-1986)
• Mercury 80 HP 4-Cyl 2.875 Bore Cross Flow 2-Stroke Outboard (1978-1979)
• Mercury 85 HP 4-Cyl 2.875 Bore Cross Flow 2-Stroke Outboard (1973-1977)

MERCURY 6-CYLINDER OUTBOARD APPLICATIONS:
• Mercury 90 HP 6-Cyl 2.875 Bore Cross Flow 2-Stroke Outboard (1978-1988)
• Mercury 135 HP 6-Cyl 2L 3.125 Bore 2-Stroke Outboard (1990-1996)
• Mercury 150 HP 6-Cyl 2L 3.125 Bore 2-Stroke Outboard (1990-1996)
• Mercury 175 HP 6-Cyl 2.4L 3.375 Chrome Bore 2-Stroke Outboard (1990-1998)
• Mercury 150 HP 6-Cyl 2.4L XR-4 3.375 Steel Bore 2-Stroke Outboard (1988-1992)
• Mercury 175 HP 6-Cyl 2.4L XR-4 3.375 Steel Bore 2-Stroke Outboard (1991-1992)
• Mercury 200 HP 6-Cyl 2.5L 3.501 Bore 2-Stroke Outboard (1991-1995)
• Mercury 150 HP 6-Cyl 2.5L EFI 3.501 Bore 2-Stroke Outboard (1992-1996)
• Mercury 175 HP 6-Cyl 2.5L EFI 3.501 Bore 2-Stroke Outboard (1992-1995)
• Mercury 200 HP 6-Cyl 2.5L EFI 3.501 Bore 2-Stroke Outboard (1992-1995)
• Mercury 150 HP 6-Cyl 2.5L Pro Max 3.501 Bore 2-Stroke Outboard (1994-1998)
• Mercury 200 HP 6-Cyl 2.5L Pro Max 3.501 Bore 2-Stroke Outboard (1994-1998)
• Mercury 150 HP 6-Cyl 2.5L XR6 3.501 Bore 2-Stroke Outboard (1992-1996)

MARINER OUTBOARD APPLICATIONS:
• All Mariner Outboard Models Requiring OEM 25-29976 by Part Number Match

MERCRUISER STERNDRIVE APPLICATIONS:
• All MerCruiser Sterndrive Models Requiring OEM 25-29976 by Part Number Match

WATER PUMP O-RING SPECIFICATIONS:
• Inside Diameter (I.D.): 3.500 Inch (88.9 mm)
• Width / Cross-Section: 0.210 Inch (5.3 mm)
• Outside Diameter (O.D.): Approximately 3.920 Inch
• Material: Nitrile (NBR) Standard Marine Grade Rubber
• Color: Black
• Type: Water Pump Assembly O-Ring Seal

FUNCTIONAL APPLICATION — WATER PUMP / GEARCASE SERVICE:
Per Sierra Marine Parts Catalog, this O-ring is identified as a Water Pump O-Ring used in the lower unit / gearcase water pump assembly. This is a routinely-replaced wear part during impeller and water pump service, sealing the water pump housing or base on Mercury 4-Cyl 2.875 bore cross flow outboards (1970-1988), Mercury 6-Cyl 2.875 bore cross flow outboards (1978-1988), and the entire Mercury V6 lineup spanning 2.0L (3.125 bore), 2.4L (3.375 bore), and 2.5L (3.501 bore) engines from 1988-1998 including XR-4, XR6, EFI, and Pro Max performance variants.

SERVICE WHEN:
• Replacing Water Pump Impeller (Routine Service)
• Performing Lower Unit / Gearcase Service
• Diagnosing Cooling System Issues
• Annual Maintenance on These Mercury Models
• Rebuilding Water Pump Assembly

FITMENT NOTE:
This is an OEM-spec replacement Water Pump O-Ring. ALWAYS verify the OEM part number 25-29976 from your service manual or Mercury parts diagram before ordering. While this O-ring is widely used across the Mercury 4-Cyl cross flow and 6-Cyl V6 lineup spanning 1970-1998, individual water pump assembly variations may use different sealing dimensions. Confirm 25-29976 is specified for your particular engine serial number before ordering.