Mercury 4.2 Diesel User Manual (English)

Questions and Answers:

J
John BellAug 14, 2025
What to do if Mercury 4.2 Diesel Engine starter motor will not crank engine, or cranks slow?
- S
  Shannon SmithAug 14, 2025
  If the starter motor won't crank the Mercury Engine, or cranks slowly, here are a few things to check: * Ensure the battery switch is turned on. * Make sure the remote control is in the neutral position. * Check and reset the circuit breaker or replace the fuse if it's open or blown. * Inspect all electrical connections and wires, especially the battery cables, for looseness or dirt. Clean and tighten any faulty connections. * Test the battery and replace it if it's bad.
E
Edward RichAug 17, 2025
Why Mercury 4.2 Diesel will not start, or is hard to start?
- A
  Alexander HardingAug 17, 2025
  If your Mercury Engine won't start or is hard to start, consider the following: * Check the lanyard stop switch. * Ensure you are following the correct starting procedure. * Verify the fuel tank isn't empty and the fuel shut-off valve is open. * Check the throttle for freedom of movement. * Replace clogged fuel filters. * Drain the tank and fill with fresh fuel if the existing fuel is stale or contaminated. * Replace any kinked fuel lines or clear any obstructions in the lines with compressed air. * Purge the fuel injection system if there's air in it. * Check wire connections.
P
Paul OdonnellAug 20, 2025
What to do if Mercury Engine runs rough, misses, or backfires?
- J
  Julie PriceAug 21, 2025
  If your Mercury Engine runs rough, misses, or backfires, try these solutions: * Check the throttle for binding or obstructions. * Replace fuel or air filters if they are clogged. * If the fuel is stale or contaminated, drain the tank and fill it with fresh fuel. * Replace any kinked fuel lines or clear obstructions in the lines using compressed air. * Purge the fuel injection system if there is air in the fuel system.
A
austindavisAug 23, 2025
What causes poor performance in a Mercury Engine?
- M
  Michelle VazquezAug 25, 2025
  If you are experiencing poor performance with your Mercury Engine, check the following: * Inspect the throttle cable and linkages to ensure the throttle is fully open. * Ensure the trim sterndrive is below the trim limit if the trim limiter is engaged. * Replace the propeller if it is damaged or improper.
J
jimmybergAug 27, 2025
What to do if Mercury 4.2 Diesel battery will not charge?
- N
  nancycannonAug 27, 2025
  If the Mercury Engine battery won't charge: * Turn off any non-essential accessories to reduce current draw. * Check all electrical connections and wires, especially battery cables, for looseness or dirt. Clean and tighten any faulty connections, and repair or replace any damaged wiring. * Replace or adjust the alternator drive belt if it is loose or in poor condition. * Test the battery.
J
James LinAug 30, 2025
What causes Mercury Engine oil pressure issues?
- O
  owensjenniferAug 30, 2025
  If you're experiencing issues with Mercury Engine oil pressure: * Check and add oil if there is insufficient oil in the crankcase. * If there is excessive oil in the crankcase (causing it to become aerated), check and remove the required amount of oil, and determine the cause of the excessive oil, such as improper filling. * Change the oil and oil filter, using the correct grade and viscosity oil, if the oil is diluted or of improper viscosity. Determine the cause for dilution, such as excessive idling.
B
Barbara HorneSep 2, 2025
What affects correct Mercury Engine temperature?
- K
  Kenneth RiveraSep 3, 2025
  Several factors can affect the correct Mercury Engine temperature: * Ensure the water inlet or seacock is open. * Replace or adjust the drive belt if it is loose or in poor condition. * Remove any obstructions from the seawater pickups or sea strainer. * Check for cause of low coolant level and repair. Fill system with proper coolant solution. * Position hose to prevent kinking (restriction). * Replace hose with wire reinforced design.
S
Susan AguilarSep 6, 2025
What to do if there is excessive bilge water in Mercury 4.2 Diesel Engine?
- C
  Christine LawrenceSep 6, 2025
  To address excessive bilge water in your Mercury Engine, drain the bilge and check for the cause of entry.
D
deniseclarkSep 9, 2025
Why is my Mercury 4.2 Diesel experiencing poor performance?
- A
  andrewbensonSep 9, 2025
  If your Mercury Engine is showing poor performance, first verify the throttle is fully open by inspecting the cable and linkages. Check the propeller for damage or if it's the correct type. Also, check for excessive bilge water and drain, investigating the cause of entry.

Mercury 4.2 Diesel Specifications

General

Engine Type	Diesel
Configuration	Inline
Cooling System	Liquid Cooled
Displacement	4.2 liters
Cylinders	6
Fuel System	Direct Injection

Summary

Section 1 - Getting to Know Your Power Package

Identification

Locating and understanding serial number decals and engine data labels.

Features and Controls

Overview of audio warning system, switches, and lanyard stop switch.

Instrumentation

Information on VesselView and SmartCraft gauges for monitoring engine data.

Remote Controls and Trim

Panel/console mount controls, power trim, and trailer switch operations.

Overload Protection and Systems

Circuit breakers, overload protection, Engine Guardian, and SeaCore systems.

Section 2 - On the Water

Safe Boating Practices

Recommendations for safe operation, equipment, and passenger safety.

Carbon Monoxide and Ventilation

Awareness of CO hazards and importance of proper boat ventilation.

Operation Essentials

Launching, duty cycle, high-output ratings, and cold weather operation.

Starting, Shifting, and Stopping

Procedures for engine start, gear engagement, and shutdown.

Safe Operation Scenarios

Guidance on high-speed operation, passenger safety, and wave jumping.

Impact and Operating Conditions

Discusses impact protection, weight distribution, cavitation, and elevation effects.

Break-In Procedures

Outlines initial engine and sterndrive break-in periods and procedures.

Section 3 - Specifications

Fuel and Coolant Specifications

Details on diesel fuel specifications and antifreeze/coolant types.

Engine and Fluid Specifications

Technical specs for engine oil, coolant, and sterndrive gear lube.

Steering and Trim Fluids

Information on approved power-assisted steering and trim fluids.

Section 4 - Maintenance

Owner and Operator Responsibilities

Defines operator and dealer duties for maintenance and service.

Maintenance Schedules

Daily, weekly, and annual maintenance tasks.

Engine Oil and Filter Service

Procedures for checking, filling, and changing engine oil and filter.

Sterndrive and Power Trim Maintenance

Covers sterndrive gear lube and power trim fluid checks, filling, and changing.

Cooling and Fuel System Maintenance

Procedures for engine coolant, air filters, and fuel filter maintenance.

Seawater System Care

Instructions for draining, flushing, and cleaning the seawater system and strainer.

Corrosion Protection

Explains galvanic corrosion and maintenance of anodes and MerCathode systems.

Drive Belts and Lubrication

Covers inspection and maintenance of drive belts, steering, throttle, and shift cables.

Section 5 - Storage

Storage Procedures

Procedures for preparing the power package for storage in various conditions.

Recommissioning After Storage

Steps for long-term storage and preparing the engine for use after storage.

Section 6 - Troubleshooting

Troubleshooting Charts

Common engine and system issues with possible causes and remedies.

Specific Troubleshooting Scenarios

Addresses issues like engine temperature, oil pressure, and remote control problems.

Section 7 - Customer Assistance Information

Owner Service and Support

Information on dealer service, parts, and problem resolution.

Contacting Mercury Marine

Provides contact details for customer service and ordering literature.

Section 8 - Maintenance Log

Maintenance Records

Templates for logging scheduled and general vessel maintenance.

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Mercury 4.2 Diesel User Manual

Table of Contents

Questions and Answers:

Mercury 4.2 Diesel Specifications

Summary

Section 1 - Getting to Know Your Power Package

Identification

Features and Controls

Instrumentation

Remote Controls and Trim

Overload Protection and Systems

Section 2 - On the Water

Safe Boating Practices

Carbon Monoxide and Ventilation

Operation Essentials

Starting, Shifting, and Stopping

Safe Operation Scenarios

Impact and Operating Conditions

Break-In Procedures

Section 3 - Specifications

Fuel and Coolant Specifications

Engine and Fluid Specifications

Steering and Trim Fluids

Section 4 - Maintenance

Owner and Operator Responsibilities

Maintenance Schedules

Engine Oil and Filter Service

Sterndrive and Power Trim Maintenance

Cooling and Fuel System Maintenance

Seawater System Care

Corrosion Protection

Drive Belts and Lubrication

Section 5 - Storage

Storage Procedures

Recommissioning After Storage

Section 6 - Troubleshooting

Troubleshooting Charts

Specific Troubleshooting Scenarios

Section 7 - Customer Assistance Information

Owner Service and Support

Contacting Mercury Marine

Section 8 - Maintenance Log

Maintenance Records

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