O - Ring Cylinder Head - Mercury / Mariner 200-300 HP 3L / 3.2L (2001, 2004-2006, 2008, 2014, 2017-2018) OEM# 25-818574 | WSM 505-50

O-Ring Cylinder Head Mercury / Mariner 200 - 300 Hp 3L / 3.2L OEM# 25-818574

This WSM o-ring cylinder head is a quality aftermarket replacement part designed for Mariner 6 Cyl 3.625 Bore 3L 225 and 15 other compatible models.

It replaces selected OEM reference numbers including 25-818574 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 17 listed fitments
• Replaces selected OEM reference numbers listed below

Product Details

• Brand: WSM
• WSM Part Number: 505-50
• Product: O-Ring Cylinder Head
• OEM Reference: 25-818574
• Application: Mariner 6 Cyl 3.625 Bore 3L 225 and 15 other compatible models

Product Fitment

This part is suitable for the following models:

• Mariner 6 Cyl 3.625 Bore 3L 225 – All Years
• Mercury 6 Cyl 3.625 Bore 3L EFI 200 – 1994-2001
• Mercury 6 Cyl 3.625 Bore 3L EFI 225 – 2003-2008
• Mercury 6 Cyl 3.625 Bore 3L EFI 250 – 1995-2008
• Mercury 6 Cyl 3.625 Bore 3L Pro Max 300 – 1995-2008
• Mercury 6 Cyl 3.625 Bore 3L XB 250 – 1998-2005
• Mercury 6 Cyl 3.6265 Bore 3.2L XS 300 – 2000-2004
• Mercury 6 Cyl 3.6265 Bore 3L Optimax 200 – 2006-2017
• Mercury 6 Cyl 3.6265 Bore 3L Optimax 225 – 1997-2018
• Mercury Mercury – 1998-2018
• Mercury 6 Cyl 3.6265 Bore 3L Optimax 300 – 2008-2014
• Mercury 6 Cyl 3.6265 Bore 3L Pro XS 200 – 2015-2018
• Mercury 6 Cyl 3.6265 Bore 3L Pro XS 225 – 2007-2018
• Mercury 6 Cyl 3.6265 Bore 3L Pro XS 250 – 2004-2018
• Mercury 6 Cyl 3.6265 Bore 3L Sport Jet 250 – 2006-2018
• 6 Cyl 3L Carb Sea Pro 225 – 2002-2006
• 1995-2001

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:

• Oil Seal Crankshaft Mercury / Mariner 200 - 300 Hp 94-18 OEM# 26-815449 – 550-37T
• O-Ring End Cap Mercury / Mariner / Mercruiser 65 - 300 Hp OEM# 2408 – 526-15
• Gasket Relief Valve Mercury / Mariner / Mercruiser 135 - 300 Hp OEM# 27-88907 – 540-28-01
• Oil Seal Crankshaft Mercury / Mariner 200 - 300 Hp 94-18 OEM# 26-830898 – 550-38T

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