Mercury 20 EFI FourStroke Service Manual

Powerhead
Section
4A - Cylinder Block/Crankcase
Table of Contents
Cylinder Block/Crankcase Specifications...........................4A-2
Piston Specifications
..........................................................4A-3
Cylinder Block and Crankcase Components..................... 4A-4
Crankshaft Components.................................................... 4A-6
Powerhead Removal..........................................................4A-8
Cylinder Block Disassembly.............................................4A-10
Electrical Component Removal................................ 4A-10
Throttle Body Removal............................................. 4A-12
Crankshaft Timing Gear Removal............................ 4A-12
Thermostat and Exhaust Cover Removal.................4A-13
Oil Strainer Removal.................................................4A-14
Crankcase and Crankshaft Removal........................ 4A-14
Piston Disassembly.................................................. 4A-16
Powerhead Cleaning, Inspection, and Repair..................4A-16
Flywheel....................................................................4A-16
Crankshaft Timing Gear............................................4A-17
Timing Belt................................................................4A-17
Anode....................................................................... 4A-17
Measuring Cylinder Bore.......................................... 4A-17
Piston Measurements............................................... 4A-17
Connecting Rod Measurements............................... 4A-19
Crankshaft................................................................ 4A-20
Crankcase Main Bearings.........................................4A-20
Connecting Rod Oil Clearance................................. 4A-23
Powerhead Assembly...................................................... 4A-24
Piston Assembly....................................................... 4A-24
Piston Ring Installation............................................. 4A-24
Piston Installation......................................................4A-25
Crankshaft Installation.............................................. 4A-26
Crankshaft Timing Gear Installation......................... 4A-28
Thermostat, Exhaust Cover, and Anode Installation
.............................................................................. 4A-28
Oil Strainer Installation..............................................4A-30
Throttle Body Installation.......................................... 4A-30
Electrical Component Installation............................. 4A-31
Powerhead Installation.....................................................4A-33
Cylinder Block/Crankcase
90-8M0125265 eng NOVEMBER 2017 © 2018 Mercury Marine Page 4A-1
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A

Mercury 20 EFI FourStroke Specifications

General

Brand	Mercury
Model	20 EFI FourStroke
Category	Engine
Language	English