O - Ring Cylinder Head - Mercury / Mariner 200-300 HP 3L (1999-2005) OEM# 25-878453 | WSM 505-52

O-Ring Cylinder Head Mercury / Mariner 200 - 300 Hp 3L OEM# 25-878453

This WSM o-ring cylinder head is a quality aftermarket replacement part designed for Mercury 6 Cyl 3.625 Bore 3L 225 and 8 other compatible models.

It replaces selected OEM reference numbers including 25-878453, 878453 and is suitable for service, repair and rebuild work.

Key Features

• Quality aftermarket replacement part from WSM
• Engineered for dependable fit, function and service life
• Designed for marine and powersports repair and maintenance
• Compatible with 28 listed fitments
• Replaces selected OEM reference numbers listed below

Product Details

• Brand: WSM
• WSM Part Number: 505-52
• Product: O-Ring Cylinder Head
• OEM Reference: 25-878453, 878453
• Application: Mercury 6 Cyl 3.625 Bore 3L 225 and 8 other compatible models

Product Fitment

This part is suitable for the following models:

• Mercury 6 Cyl 3.625 Bore 3L 225 – 1999
• Mercury 6 Cyl 3.625 Bore 3L 225 – 2000
• Mercury 6 Cyl 3.625 Bore 3L 225 – 2001
• Mercury 6 Cyl 3.625 Bore 3L EFI 200 – 2003
• Mercury 6 Cyl 3.625 Bore 3L EFI 200 – 2004
• Mercury 6 Cyl 3.625 Bore 3L EFI 225 – 2002
• Mercury 6 Cyl 3.625 Bore 3L EFI 225 – 2003
• Mercury 6 Cyl 3.625 Bore 3L EFI 225 – 2004
• Mercury 6 Cyl 3.625 Bore 3L EFI 250 – 2002
• Mercury 6 Cyl 3.625 Bore 3L EFI 250 – 2003
• Mercury 6 Cyl 3.625 Bore 3L EFI 250 – 2004
• Mercury 6 Cyl 3.625 Bore 3L Pro Max 300 – 2001
• Mercury 6 Cyl 3.625 Bore 3L Pro Max 300 – 2002
• Mercury 6 Cyl 3.625 Bore 3L Pro Max 300 – 2003
• Mercury 6 Cyl 3.625 Bore 3L Pro Max 300 – 2004
• Mercury 6 Cyl 3.625 Bore 3L Pro Max 300 – 2005
• Mercury 6 Cyl 3.625 Bore 3L XB 250 – 2000
• Mercury 6 Cyl 3.625 Bore 3L XB 250 – 2001
• Mercury 6 Cyl 3.625 Bore 3L XB 250 – 2002
• Mercury 6 Cyl 3.625 Bore 3L XB 250 – 2003
• Mercury 6 Cyl 3.625 Bore 3L XB 250 – 2004
• Mercury 6 Cyl 3.6265 Bore 3L Optimax 200 – 2001
• Mercury 6 Cyl 3.6265 Bore 3L Optimax 200 – 2002
• Mercury 6 Cyl 3.6265 Bore 3L Optimax 225 – 2001
• Mercury 6 Cyl 3.6265 Bore 3L Optimax 225 – 2002
• Mercury 6 Cyl 3L Carb Sea Pro 225 – 1999
• Mercury 6 Cyl 3L Carb Sea Pro 225 – 2000
• Mercury 6 Cyl 3L Carb Sea Pro 225 – 2001

Why Buy WSM

WSM is a trusted manufacturer of aftermarket marine and powersports parts, known for dependable quality, strong fitment coverage and workshop-ready replacement components.

You May Also Need

Browse related parts for compatible models:

• Bolt Connecting Rod Mercury / Mariner 65 - 125 / 200 - 300 Hp (Sold Each) OEM# 10-94320 – 805-204
• Tilt Tube Stainless Steel Mercury / Mariner / Force 65 - 300 Hp OEM# 826125A1 – 986-165
• Gasket Water Pump Force / Mercury / Mariner / Mercruiser 40 - 300 Hp OEM# 27-817277 – 447-329
• O-Ring Crankshaft Chrysler / Force / Mercury / Mariner / Mercruiser / Yamaha 6 - 300 Hp OEM# 25-90011 – 526-13

Please use the fitment guide, OEM references and images to confirm this is the correct part before ordering.