Gasket Head - Mercury / Mariner 135 / 150 HP 2.5L Optimax (1999) OEM# 27-8525203 | WSM 505-41

Gasket Head Mercury / Mariner 135 / 150 Hp 2.5L Optimax 98-99 OEM# 27-8525203

This WSM gasket head is a quality aftermarket replacement part designed for Mariner 6 Cyl 3.501 Bore 2.5L Optimax 135 and 2 other compatible models.

It replaces selected OEM reference numbers including 27-8525203 and is suitable for service, repair and rebuild work.

Key Features

• Quality replacement gasket designed for dependable sealing performance
• Ideal for service, repair and engine rebuild work
• Manufactured for fit, durability and reliable installation
• Compatible with 3 listed fitments
• Replaces selected OEM reference numbers listed below

Product Details

• Brand: WSM
• WSM Part Number: 505-41
• Product: Gasket Head
• OEM Reference: 27-8525203
• Application: Mariner 6 Cyl 3.501 Bore 2.5L Optimax 135 and 2 other compatible models

Product Fitment

This part is suitable for the following models:

• Mariner 6 Cyl 3.501 Bore 2.5L Optimax 135 – All Years
• Mercury 6 Cyl 3.501 Bore 2.5L Optimax 150 – 1998-1999
• Mercury – 1998-1999

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.

About the Mercury 135-200 HP Outboard Engines

Mercury and Mariner 135-200 HP outboard engines are widely used across recreational and performance boating applications. These engines have long-standing aftermarket support, making quality replacement gaskets, ignition, fuel and powerhead parts important for service and rebuild work.

You May Also Need

Browse related parts for compatible models:

• Ignition Coil Mercury 75 - 350 Hp Verado OEM# 184-0002 – 376-0615
• Piston Clips Mercury / Mariner 135 - 175 Hp 2.5L Optimax 01-14 OEM# 53-8320811 – 400-49
• Fuel Pump Mercury / Mariner 135 - 225 Hp DFI OEM# 855427A1 – 600-113
• Fuel Pump Mercury / Mariner 135 - 225 Hp DFI OEM# 855427A1 – 600-113-W

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