ILMOR MV8 Owner's Manual

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INTRODUCTION

Please read this Owner's Manual completely prior to operating the engine

and boat for the first time. The Owner's Manual contains information

critical for safe operation, and to activate and keep the limited warranty

statement in effect throughout the applicable warranty period. Continuing

the appropriate maintenance and care going forward can ensure long-

term enjoyment of the MV8 engine. DO NOT OPERATE THE ENGINE

WITHOUT FIRST READING THE ENTIRE MV8 OWNER'S MANUAL

AND ALL SUPPORTING DOCUMENTATION, AS WELL AS THE

BOAT OWNER'S MANUAL.

WELCOME

Ilmor Marine, LLC, is pleased to welcome you to boating enjoyment

available only through use of the extraordinary MV8 engines. Ilmor is

a recognized leader in the marine industry, hav ing originated through

championship-caliber, high-performance engines. Our experience

inevitably led to the development of the MV8, offering 5.7, 6.0, 6.2 and 7.4

liter versions. The MV8 provides the kind of horsepower necessary to plane

with pulse-pounding quickness while equally ensuring the reliability and

smoothness necessary for just-above-idle investigation of interesting coves

and shorelines. It's all here.

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Need help?

Do you have a question about the MV8 and is the answer not in the manual?

Questions and answers

Pete

July 6, 2025

MV8 5.7L closed cooling in 2016 mastercraft X10 overheat everytime. new impeller, good water flow no leaks water or coolant new thermostat as well as new temp sensor cannot seem to figure this one out.

1 comments:

Mr. Anderson

August 27, 2025

If the ILMOR MV8 5.7L engine is overheating despite having a new impeller, good water flow, no leaks, a new thermostat, and a new temperature sensor, possible causes include:

1. Blockage in the transmission cooler, which can restrict water flow and cause overheating.
2. Failure of the raw water impeller in a way not related to its condition (e.g., incorrect installation).
3. Water contamination in the transmission oil due to cooler failure, reducing cooling efficiency.
4. Electrical or sensor malfunction not resolved by replacing the temperature sensor (e.g., wiring issues or other sensor faults).

It is recommended to have the system checked by a certified Ilmor dealer.

This answer is automatically generated

Summary of Contents for ILMOR MV8

Page 1 Our experience inevitably led to the development of the MV8, offering 5.7, 6.0, 6.2 and 7.4 liter versions. The MV8 provides the kind of horsepower necessary to plane...
Page 2 Owner’s Manual. Realistically, this Owner’s Manual also cannot address every potential issue that may arise from the operation and use of the MV8. A reasonable effort was made to make this Owner’s Manual as accurate and complete as possible, but photographs and drawings may be only representational.
Page 3: Introduction
INTRODUCTION TRADEMARKS All non-Ilmor trademarks, service marks, logos, slogans and trade names are the properties of their respective owners. The following is a list of trademarks that may be used throughout this manual. Chevrolet Racing Diacom PC Software Dodge Viper...
Page 5: Table Of Contents
INSPECT THE ENGINE FOR LOOSE OR MISSING HARDWARE ...................4-6 INSPECT THE THROTTLE AND SHIFT CABLES FOR KINKS, WEAR AND INTERFERENCE ..........4-6 INSPECT THE FUEL AND EXHAUST SYSTEMS FOR LEAKS ..4-6 CHECK THE SEA STRAINER – POST-ENGINE START-UP ..4-7 © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 6 INSPECTING AND CLEANING THE BATTERY CONNECTIONS AND HOLD-DOWNS ......... 7-15 STORAGE AND WINTERIZATION ......... 8-1 FUEL SYSTEM TREATMENT ..............8-1 OIL STORAGE/WINTERIZATION ............8-2 COOLING SYSTEM STORAGE AND WINTERIZATION .....8-2 BATTERY WINTERIZATION .............8-4 RECOMMISSIONING AFTER STORAGE/WINTERIZATION ..8-4 © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 7 Electronic Emission-Related Control Parts Warranty ....9-7 Direct Emission-Related Control Parts Warranty ......9-7 TROUBLESHOOTING ............. 10-1 SPECIFICATIONS AND SERVICE LOG ......11-1 ENGINE SPECIFICATIONS .............. 11-1 Requirements and Recommendations ..........11-2 SERVICE LOG ..................11-3 © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 9: Safety
Key to safety is the prescribed maintenance of the engine and drive train as described in this Owner’s Manual, on www.ilmor.com, and through information and directives provided by the suppliers of parts for the drive train.
Page 10 SECTION 1 ILMOR MV8 OWNER’S MANUAL Throughout the MV8 Owner’s Manual, specific safety information will be highlighted with symbols designed to draw particular attention to specific information. These will include: This safety alert symbol appears with most safety statements. It means attention, become alert, your safety is involved! Please read and abide by the message that follows the safety alert symbol.
Page 11: Direct Safety Concerns
SAFETY DIRECT SAFETY CONCERNS Whenever an MV8 engine is operated within the confines of an engine compartment, it is extremely important to follow the boat manufacturer’s instructions regarding venting of the engine compartment prior to or during low-speed/idle operation. One of the most critical safety matters affecting boaters is the matter of carbon monoxide emission.
Page 12: Dangers, Warnings, Cautions And Notices
All requirements of the Federal Occupational Safety and Health Act must be met when Ilmor products are operated in areas that are under the jurisdiction of the United States of America. Ilmor products operated in other countries must be installed, operated and serviced in compliance with any and all applicable safety requirements of that country.
Page 13 A WARNING! Always use genuine Ilmor Marine, LLC, replacement parts intended for the MV8 engine. The electrical and ignition components have been designed to comply with U.S. Coast Guard regulations intended to minimize the possibility of fire and/ or explosion.
Page 14 A WARNING! Never realign the wiring or in any way alter the wiring of the MV8 engine. Doing so may result in damage to the engine, which is not covered under warranty, and sufficient voltage may be present to cause serious injury and/or death.
Page 15 (such as a flame-producing pilot light in a heater) could also result in property damage and serious injury or death. A WARNING! Always replace parts of the fuel system with Ilmor- authorized parts only. All fuel system lines and connections must meet the requirements of U.S.
Page 16 NOTICE: Always use a high-quality gasoline from a reputable source. Damage to the engine by use of low-quality gasoline or gasoline with an octane rating below the minimum level listed for Ilmor MV8 engines will void the warranty on the engine.
Page 17 10 hours proper operation, but not later than 25 hours. At that time, an oil change should be performed by a certified Ilmor dealer, who will be able to “read” the oil and filter to determine if the proper break-in of the engine components appears to be occurring.
Page 18 NOTICE: Any exposure to brackish or salt water requires a closed cooling system. Operating your open cooled engine in brackish or salt water can and will void your warranty. NOTICE: If power steering fluid is not visible, contact your Ilmor service center immediately. Severe engine damage could occur. 1-10...
Page 19: Introducing The Mv8
A WARNING! Never realign the wiring or in any way alter the wiring of the MV8 engine. Doing so may result in damage to the engine, which is not covered under warranty, and sufficient voltage may be present to cause serious injury and/or death.
Page 20: Exhaust System
ILMOR MV8 OWNER’S MANUAL EXHAUST SYSTEM Ilmor MV8 engines are equipped with “wet” marine exhaust systems. In a wet marine exhaust system, raw water enters the exhaust elbows (also referred to as “downturn adapters”), where it mixes with the exhaust gases.
Page 21: Fuel System
There are two main types of cooling systems used in Ilmor engines, one of which will be found with each engine depending upon the type selected: 1.
Page 22: Open Cooling System
The engine recirculation pump recirculates coolant through the engine and exhaust manifolds. Raw water never enters the engine or exhaust manifolds. © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 23: Electrical System
INTRODUCING THE MV8 ELECTRICAL SYSTEM The electrical system on the MV8 is a 12-volt negative ground system. As a result, it is important to keep in mind that operators must avoid reverse polarity, which could lead to extensive damage of the electronics. Any damage occurring as a result of reverse polarity will not be covered by warranty.
Page 24: Boat/Engine Interface Wiring
Boat/Engine Interface Wiring WARNING! Never realign the wiring or in any way alter the wiring of the MV8 engine. The electrical system of the MV8 is primarily self-contained in a preassembled unit. The interface with boat wiring follows established practices and conforms to regulatory guidelines.
Page 25: Alarms
The alarm will shut off momentarily. After the engine is started the alarm will not go off again. If the alarm sounds or displays at any other time or for any other reason, contact a certified Ilmor dealer before restarting the engine.
Page 27: Fueling The Mv8
OEM specifications. Ilmor recommends a daily inspection to ensure that no fuel lines are leaking. Never start the boat if there is evidence of fuel leaks or fumes. © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 28: Fuel Requirements
FUEL REQUIREMENTS The Ilmor MV8 engine (5.7L, 6.0L, 6.2L and 7.4L) requires a minimum of 87 octane fuel. The octane number is based on the pump octane number, which is (R + M)/2, where R is the research octane number and M is the motored octane number.
Page 29: Oxygenated Gasoline Or Gasoline Containing Alcohol
Leaded fuels may NOT be used in the MV8 engine. Gasoline containing levels higher than 10% ethanol or gasoline containing any methanol is NOT TO BE USED in the MV8 engine. If the presence of alcohol in the gasoline is unknown, frequent inspections of the fuel system are required.
Page 31: Before Each Use
Engine Specifications on page 11-1. DO NOT USE OIL ADDITIVES AT ANY TIME. Before boating, be sure to also follow the procedure for checking the oil level after engine start-up. See Check the Engine Oil Level on page 4-8. © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 32: Check The Sea Strainer - Pre-Engine Start-Up
Always pay attention to your temperature gauge, even if you are carefully performing this check. Failure of the raw water impeller or blockage of the transmission cooler are frequent causes of overheating. © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 33: Check The Coolant Level
50/50 with water. The cooling system will take between 5.8 gal (22 L) and 6.8 gal (26 L) of coolant in total. 3. If the tank was completely or nearly empty, see your certified Ilmor dealer for immediate assistance as the engine cooling system will likely require purging.
Page 34: Check The Power Steering Fluid For Engines With Integral Reservoir (If Equipped)
1) FULL HOT Mark 2) FULL COLD Mark 3) ADD Mark NOTICE: If power steering fluid is not visible, contact your Ilmor service center immediately. Severe engine damage could occur. NOTE: Power steering fluid does not require changing. For remote power steering reservoir systems, see the boat manufacturer’s manual for proper maintenance instructions, or contact your authorized Ilmor service center for assistance.
Page 35: Check The Serpentine Belt For Looseness Or Damage
3. Too-loose or too-tight tension is indicative that it is time for service on the belt. This should be done by a trained Ilmor service technician. 4. Check the underside of the belt that runs in contact with the pulleys.
Page 36: Inspect The Engine For Loose Or Missing Hardware
2. Follow each cable back under the floorboards and feel for any kinks or wear on the outer jacket. Any sign of cable damage is cause for immediate replacement. See a certified Ilmor dealer for assistance. INSPECT THE FUEL AND EXHAUST...
Page 37: Check The Sea Strainer - Post-Engine Start-Up
Ilmor dealer. If the charge has fallen too low or if the battery is older or fails to hold a charge at the expected level, the boat may not start.
Page 38: Check The Transmission Fluid/Oil Level
Overfill may result in damage to the engine that may not be covered by the warranty. Use oil as specified in Engine Specifications on page 11-1. DO NOT USE OIL ADDITIVES AT ANY TIME. © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 39: After Each Use
AFTER EACH USE CHECK THE RAW WATER PICK-UP For all Ilmor equipped boats, a check of the raw water pick-up is necessary. Located beneath the boat, under the water line on the hull is the raw water pick-up. Even when boating on clean-appearing bodies of water, a check of this pick-up should be done after every outing to determine if there is any debris.
Page 40: Check For Leaks
Any sign of leakage should be brought to the attention of a certified Ilmor dealer immediately. CLEAN ANY RESIDUE Normal operations will still result in a small amount of ambient fluids. If...
Page 41: Starting, Stopping And New Engine Break-In
This requires the boat to be in an operational-sized body of water or hooked up to the suction side of a raw water pump by an Ilmor-approved water supply in a dealership. If the engine operates without water in the cooling system, the exhaust system will overheat and could potentially create an on-board fire.
Page 42: First Hours Of Operation
10 hours proper operation, but not later than 25 hours. At that time, an oil change should be performed by a certified Ilmor dealer, who will be able to “read” the oil and filter to determine if the proper break-in of the engine components appears to be occurring.
Page 43: After Initial Hours Of Operation
STARTING, STOPPING AND NEW ENGINE BREAK-IN 3. The boat MUST be returned to the certified Ilmor dealer for a mandatory oil change between 10 and 25 hours of operation. This ensures the service staff will be able to determine whether any internal issues may be apparent.
Page 44: Starting The Engine
Also ensure that the engine oil pressure is greater than 10 psi (70 kPa), according to the gauge on the instrument panel. © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 45: Shifting Gears
See also the boat manufacturer’s Owner’s Manual for operational hints and tips that can enhance the enjoyment of the boat’s and drive train’s integration. © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 47: Maintenance
Do not attempt to replace fuel filter without special tools. Doing so may damage fuel line or filter. A damaged fuel line or filter may leak and cause a fire or explosion. © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 48 Ilmor dealer. Service technicians there have the proper equipment, training and resources to best meet your service needs. Please note that routine maintenance is not covered by the Ilmor Marine Limited Warranty. For details, consult the limited warranty statement.
Page 49: Change The Engine Oil And Filter
(as some dealerships do), have a certified Ilmor dealer perform this service A list of recommended oil for use in each MV8 engine can be found in Engine Specifications on page 11-1.
Page 50 Engine damage due to incorrect oil usage, oil changes and oil levels, or other failure to follow engine oil procedures can be costly and may void the warranty. © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 51: Check The Power Steering Fluid For Engines With Integral Reservoir
1) FULL HOT Mark 2) FULL COLD Mark 3) ADD Mark NOTICE: If power steering fluid is not visible, contact your Ilmor service center immediately. Severe engine damage could occur. NOTE: Power steering fluid does not require changing. For remote power steering reservoir systems, see the boat manufacturer’s manual for proper maintenance instructions, or contact your authorized Ilmor service center for assistance.
Page 52: Change The Fuel/Water Separator
Inspect the fuel/water separator for any leaks. Correct any leak if found, clean spilled fuel immediately and repeat steps 8 and 9. © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 53: Replace The High-Pressure Fuel Filter
If any components appear to be worn or damaged, contact your authorized Ilmor service center for additional assistance. 7. Install new high-pressure fuel filter, in the previously noted flow direction, inside the mounting clip on the engine.
Page 54: Change The Transmission Fluid/Oil And Filter
AND FILTER Refer to the transmission service manual for specific service instructions and oil/filter requirements. NOTE: It is recommended that this service be performed by a certified Ilmor dealer. CHECK THE TRANSMISSION COOLER This applies to all MV8 engines except the 7.4L.
Page 55: Replace The Raw Water Impeller/Sea Pump Impeller
Debris entering the impeller inevitably will damage it. However, the impeller serves its purpose in deflecting debris and keeping it out of much more expensive internal engine parts. © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 56: Drain Raw Water (Sea Water)
Drain other components that contain raw water, such as the water heater. 5. Torque knock sensor retaining nut to 15 ft-lb (20 N·m). 7-10 © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 57: Check The Engine Coolant Level
If the tank was completely or nearly empty, see your authorized Ilmor dealer for immediate assistance as the engine cooling system will likely require purging. This function should be completed only by a trained Ilmor service technician.
Page 58: Fill The Engine Coolant
2. Flush fresh water through the coolers from the raw water fittings. An adapter may be needed. It is better to flush water from one end of the cooler and then from the other end. This should flush out any foreign particulates. 7-12 © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 59: Replace The Serpentine Belt
If there is any uncertainty, seek assistance from your authorized Ilmor service center. If the belt is too loose and or is too tight, it will cause the electrical system to malfunction. This could occur during an outing and strand the boaters.
Page 60: Cleaning The Engine Compartment And Preventing Corrosion
A protective marine oil may be applied to exposed metal to halt the acceleration of corrosion. Failure to properly clean boat or pay attention to corrosion matters will void the warranty. 7-14 © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 61: Inspecting And Cleaning The Battery Connections And Hold-Downs
NOTICE: Never install accessories or add-on equipment that is not approved by Ilmor. Add-on equipment may adversely affect the alternator output or overload the electrical system. Any damage caused as a result will not be covered by the warranty.
Page 63: Storage And Winterization
Fuel systems on all boats equipped with Ilmor MV8 engines MUST be properly prepared for storage periods exceeding 1 month, as outlined in this Owner’s Manual. Owners are encouraged to seek assistance from a certified Ilmor dealer to properly prepare the drive train for periods of inactivity exceeding 1 month.
Page 64: Oil Storage/Winterization
Fuel systems on all boats equipped with Ilmor MV8 engines MUST be properly prepared for storage periods exceeding 1 month. Owners are encouraged to seek assistance from a certified Ilmor dealer to properly prepare the drive train for periods of inactivity exceeding 1 month.
Page 65: Storage And Winterization
3. Fill sea strainer if not full by end of procedure. 4. Fill downturn exhaust adapters with 1/4 to 1/2 gal (1 to 2 L) of antifreeze. 5. Reinstall hoses. © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 66: Battery Winterization
4. Visually inspect the fuel system. If there appears to have been undue weathering or any leaks have appeared over the storage/winterization period, contact your certified Ilmor dealer for correction. DO NOT start the engine if there is any appearance of leakage or rupture of any component of the fuel system.
Page 67: Emissions
ECI label. ECI labels must not be removed or tampered with by anyone. If replacement decals are needed, contact Ilmor Marine, LLC, promptly. Engines with the CE mark (present in the lower right corner of the ECI label) affirm that the Declaration of Conformity applies.
Page 68: Emissions Control System Information
A Star Label is also placed on the intake manifold plenum of each certified Ilmor Marine, LLC, engine. A conventional power (373 kW / 500 bhp or less) Ilmor Marine MV8 engine has a Four Star - Super Ultra Low Emission rating. This indicates that the engine has 90% lower emissions than One Star - Low Emission engines.
Page 69: Environmental Label
EMISSIONS ENVIRONMENTAL LABEL Each boat equipped with an Ilmor MV8 engine will have an Environmental Label with the appropriate Star Label box check-marked according to the engine’s emissions standards compliance level. It is the responsibility of the selling dealer to include the Environmental Label, and it must be marked in the correct box to match the Star label on the engine and the boat.
Page 70: California And U.s. Epa Emission Control Warranty Statement
Your Warranty Rights and Obligations The California Air Resources Board, U.S. Environmental Protection Agency and Ilmor Marine, LLC are pleased to explain the emission control system warranty on your 2013 model year and later sterndrive/inboard engine. In the United States, new sterndrive/inboard engines must be designed, built and equipped to meet all State and Federal mandated anti- smog standards.
Page 71: Owner's Warranty Responsibilities
You are responsible for presenting your sterndrive/inboard engine to an Ilmor Marine, LLC authorized service center as soon as a problem exists. The warranty repairs will be completed in a reasonable amount of time, not to exceed 30 days.
Page 72: Emission Control System Warranty
California Air Resources Board or the U.S. EPA may be reason for not warranting a claim, at the discretion of Ilmor Marine, LLC. In the case of non-exempted add-on(s) or modified part(s) causing failure to a warranted part, the warranted part will not be covered.
Page 73: Electronic Emission-Related Control Parts Warranty
Oil Pressure sensor*** Covered up to, but not including, the first required replacement only. See the Maintenance Schedule in the Owner’s Manual. ** MV8 5.7L only *** MV8 6.0L and 7.4L only Direct Emission-Related Control Parts Warranty Systems Covered Parts Description...
Page 75: Troubleshooting
Have dealer tighten or replace the high-tension leads. Plugged PCV valve. Have dealer replace the PCV valve. Weak ignition coil. Have dealer replace the ignition coil. Vacuum leak. See certified Ilmor dealer. 10-1 © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 76 Alignment of the Front End Accessory Spray the serpentine belt riding Drive (FEAD). surface between the alternator and raw water pump with water. Replacement of the FEAD bracket and belt. Inspect and/or replace belt tensioner. 10-2 © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 77: Specifications And Service Log
6 gal (22 L) 6 gal (22 L) Normal Operating 140°F (60°C) – 140°F (60°C) – 140°F (60°C) – 140°F (60°C) – Temperature Range 190°F (88°C) 190°F (88°C) 190°F (88°C) 190°F (88°C) 11-1 © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 78: Requirements And Recommendations
5.7L, 6.0L and 6.2L Closed Cooled, 7.4L Open Cooled – MV8V-1179 Serpentine Belt 5.7L – PV06396 6.0L, 6.2L, 7.4L – PV06493 Transmission Oil See manufacturer’s owner manual Transmission Filter See manufacturer’s owner manual 11-2 © 5/2013 Ilmor Marine, LLC, Version 1.0...
Page 79: Service Log
Engine oil and filter Engine coolant Power steering fluid Transmission fluid Serpentine belt Raw water impeller Sea pump Spark arrestor Engine timing (5.7L only) Spark plugs Spark plug wires Shaft alignment Heat exchanger(s) Zinc anodes 11-3 © 5/2013 Ilmor Marine, LLC, Version 1.0...

ILMOR MV8 Owner's Manual

Introduction

Safety

Introducing the Mv8

Fueling the Mv8

Before each Use

After each Use

Starting, Stopping and New Engine Break-In

BreakIn

Maintenance

Storage and Winterization

Emissions

Troubleshooting

Specifications and Service Log

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Need help?

Questions and answers

Related Manuals for ILMOR MV8

Summary of Contents for ILMOR MV8

Table of Contents