1998-2005 Mercury Mariner 75HP 2-Stroke Outboard OEM Service & Repair Manual

Quick Reference Data VEHICLE HISTORY DATA MODEL: YEAR: VIN NUMBER: ENGINE SERIAL NUMBER: CARBURETOR SERIAL NUMBER OR I.D. MARK: Record the numbers here for your reference. MAINTENANCE SCHEDULE Maintenance interval Maintenance required Before each use Check the lanyard switch operation* Inspect the propeller for damage Check the propeller nut tightness Inspect the fuel system for leakage Check the outboard mounting bolt tighteness Check the steering for binding or looseness Check the shift and throttle control After each use Flush the cooling system Wash debris from the gearcase After the first 10 days of operation Check the gearcase lubricant level Every 30 day or 50 hours of usage Check the gearcase lubricant level IX (continued)

MAINTENANCE SCHEDULE (continued) Maintenance interval Maintenance required Once a season or 100 hours of usage Lubricate the steering system Lubricate tiller control pivots* Lubricate the tilt and swivel shaft Lubricate the shift and throttle linkages/cables Check the tightness of all accessible fasteners Clean and inspect the spark plugs Remove carbon from the combustion chambers Inspect fuel filters for contamination Check control cable adjustments Adjust the carburetors* Test and inspect the battery Check ignition timing Check trim/tilt fluid level (Chapter Eleven) Clean and inspect sacrificial anodes Lubricate the drive shaft splines Lubricate the propeller shaft splines Change the gearcase lubricant Lubricate the starter motor pinion Clean remote fuel tank filter* Change the water separating filter (EFI)* Inspect or replace the water pump impeller Replace the compressor air filter (Optimax)* Clean the compressor cooling water strainer* Before long term storage Drain and refill the gearcase lubricant *This maintenance item does not apply to all models. LUBRICANT CAPACITIES Model Oil capacity Gearcase capacity 65 jet, 75 hp and 90 hp 1 gal. (3.8 liter)* 22.5 oz. (665 ml)* 80 jet and 100-125 hp (except 115 Optimax) 1.4 gal (5.3 liter)* 22.5 oz. (665 ml)* 105 jet and 140 jet 12.9 qt. (12.2 liter) – 135-200 hp (except Optimax) 12.9 qt. (12.2 liter)* 22.5 oz. (665 ml)* 115-175 hp Optimax models 13.5 qt. (12.8 liter)* 22.5 oz. (665 ml)* 200/225 hp Optimax, 225 hp and 250 hp 13.5 qt. (12.8 liter) 28.0 oz. (828 ml)* *Approximate capacity. Always add lubricant until it reaches the full level. SPARK PLUG RECOMMENDATIONS Model Recommended plug Spark plug gap 65 jet, 75 hp and 90 hp NGK BUHW-2 Surface gap plug Alternate plug (resistor type) NGK BUZHW-2 Surface gap plug 80 jet, 100 hp, 115 hp and 125 hp NGK BP8H-N-10 0.040 in. (1.0 mm) Alternate plug (resistor type) NGK-BPZ8H-N-10 0.040 in. (1.0 mm) 105 jet and 140 jet 1998 and 1999 NGK BU8H Surface gap plug 2000-on NGK BPZ8HS-10 0.040 in. (1.0 mm) 135-200 hp (except Optimax) 1998 and 1999 NGK BU8H surface gap plug 2000-on NGK BPZ8HS-10 0.040 in. (1.0 mm) X (continued)

SPARK PLUG RECOMMENDATIONS (continued) Model Recommended plug Spark plug gap 115-150 hp (Optimax models) NGK PZFR5F-11 0.040 in. (1.0 mm) Alternate plug NGK ZFR5F-11 0.040 in. (1.0 mm) Alternate plug Champion RC12MC4 0.040 in. (1.0 mm) 200 and 225 hp (Optimax models) 1998 and 1999 NGK PZFR5F-11 0.040 in. (1.0 mm) Alternate plug NGK ZFR5F-11 0.040 in. (1.0 mm) 2000 Champion QC12GMC 0.040 in. (1.0 mm) 2001-on NGK PZFR5F-11 0.040 in. (1.0 mm) 225 and 250 hp (except Optimax) Champion QL77CC 0.035 in. (0.9 mm) BATTERY CAPACITY Provides continuous Approximate Accessory draw power for: recharge time 80 amp-hour battery 5 amps 13.5 hours 16 hours 15 amps 3.5 hours 13 hours 25 amps 1.6 hours 12 hours 105 amp-hour battery 5 amps 15.8 hours 16 hours 15 amps 4.2 hours 13 hours 25 amps 2.4 hours 12 hours STANDARD TORQUE SPECIFICATIONS Screw or nut size in.-lb. ft.-lb. N•m U.S. Standard 6-32 9 – 1.0 8-32 20 – 2.3 10-24 30 – 3.4 10-32 35 – 4.0 12-24 45 – 5.1 1/4-20 70 – 7.9 1/4-28 84 – 9.5 5/16-18 160 13 18.1 5/16-24 168 14 19.0 3/8-16 – 23 31.1 3/8-24 – 25 33.8 7/16-14 – 36 48.8 7/16-20 – 40 54.2 1/2-13 – 50 67.8 1/2-20 – 60 81.3 Metric M5 36 – 4.1 M6 70 – 8.1 M8 156 13 17.6 M10 – 26 35.3 M12 – 35 47.5 M14 – 60 81.3 XI

Chapter One General Information This detailed, comprehensive manual contains com- plete information on maintenance and overhaul. Hun- dreds of photos and drawings guide the reader through every step-by-step procedure. Troubleshooting, tune-up, maintenance and repair pro- cedures are not difficult with the necessary tools and equip- ment, and the ability to use them. Anyone with some mechanical ability can perform most of the procedures in this manual. See Chapter Two for more information on tools and techniques. A shop manual is a reference. Clymer books are de- signed for finding information quickly. All chapters are thumb tabbed and important topics are indexed at the end of the manual. All procedures, tables, photos and instruc- tions in this manual assume the reader may be working on the machine or using the manual for the first time. Store the manual with other tools in the workshop or boat. It will help in gaining a better understanding of how the boat runs, and help to lower repair and maintenance costs. MANUAL ORGANIZATION Chapter One provides general information useful to boat owners and mechanics. Chapter Two discusses the tools and techniques for pre- ventative maintenance, troubleshooting and repair. Chapter Three provides troubleshooting procedures for all engine systems and individual components. Chapter Four provides maintenance, lubrication and tune-up instructions. Additional chapters cover storage, adjustment and spe- cific repair instructions. All disassembly, inspection and assembly instructions are in step-by-step form. Specifica- tions are included at the end of the appropriate chapters. WARNINGS, CAUTIONS AND NOTES The terms, WARNING, CAUTION and NOTE have specific meanings in this manual. 1

A WARNING emphasizes areas where injury or even death could result from negligence. Mechanical damage may also occur. WARNINGS are to be taken seriously . A CAUTION emphasizes areas where equipment dam- age could occur. Disregarding a CAUTION could cause permanent mechanical damage, though injury is unlikely. A NOTE provides additional information to make a step or procedure easier or clearer. Disregarding a NOTE could cause inconvenience, but would not cause equip- ment damage or personal injury. TORQUE SPECIFICATIONS Torque specifications throughout this manual are given in foot-pounds (ft.-lb.), inch-pounds (in.-lb.) and newton meters (N•m). Torque wrenches calibrated in me- ter-kilograms can be used by performing a simple conver- sion: move the decimal point one place to the right. For example, 4.7 mkg = 47 N•m. This conversion is accurate enough for mechanical repairs even though the exact mathematical conversion is 3.5 mkg = 34.3 N•m. ENGINE OPERATION All marine engines, whether two- or four-stroke, gaso- line or diesel, operate on the Otto cycle of intake, compres- sion, power and exhaust phases. A two-stroke engine requires one crankshaft revolution (two strokes of the pis- ton) to complete the Otto cycle. All Mercury and Mariner engines covered in this manual are of the two-stroke de- sign. Figure 1 shows typical gasoline two-stroke engine operation. Optimax models use a direct fuel injection system. On these models, fuel is injected directly into the combustion chamber after the exhaust port is covered; preventing un- burned fuel from exiting along with the exhaust gases. Compared to typical two-stroke engines, direct fuel in- jected engines run smoother, emit far less unburned fuel, use less oil and provide improved fuel economy. Figure 2 shows direct injection two-stroke engine operation. FASTENERS The material and design of the various fasteners used on marine equipment are specifically chosen for perfor- mance and safety. Fastener design determines the type of tool required to work with the fastener. Fastener material is carefully selected to decrease the possibility of physical failure or corrosion. See Galvanic Corrosion in this chap- ter for information on marine materials. Threaded Fasteners Nuts, bolts and screws are manufactured in a wide range of thread patterns. To join a nut and bolt, the diame- ter of the bolt and the diameter of the hole in the nut must be the same. The threads must also be compatible. Determine if the threads on the fasteners are compatible by turning the nut on the bolt (or bolt into its respective opening) with fingers only. Make sure both pieces are clean. If much force is required, check the thread condi- tion on each fastener. If the thread condition is good but the fasteners jam, the threads are not compatible. Four important specifications describe the thread: 1. Diameter. 2. Threads per inch. 3. Thread pattern. 4. Thread direction. Figure 3 shows the first two specifications. Thread pat- tern is more subtle. Italian and British standards exist, but the most commonly used by marine equipment manufac- turers are American and metric. The root and top of the thread are cut differently as shown in Figure 4. Most threads are cut so the fastener must be turned clockwise to tighten it. These are called right-hand threads. Some fasteners have left-hand threads; they must be turned counterclockwise for tightening. Left-hand threads are used in locations where normal rotation of the equipment would loosen a right-hand threaded fastener. Fasteners with left-hand threads are identified in the in- structions. Machine Screws There are many different types of machine screws (Fig- ure 5). Most are designed to protrude above the secured surface (rounded head) or be slightly recessed below the surface (flat head). In some applications, the screw head is recessed well below the fastened surface. Figure 6 shows a number of screw heads requiring different types of turn- ing tools. See Chapter Two for detailed information. Bolts Commonly called bolts, the technical name for these fasteners is cap screw. They are normally described by di- ameter, threads per inch and length. For example, 1/4-20 × 1 indicates a bolt that is 1/4 in. in diameter with 20 threads per inch, and is 1 in. long. The measurement across two flats on the head of the bolt indicates the proper wrench size to use. 2 CHAPTER ONE

GENERAL INFORMATION 3 1 1 As the piston travels downward, it uncovers the exhaust port (A) allowing the exhaust gases to leave the cylinder. A fresh air-fuel charge, which has been compressed slightly in the crankcase, enters the cylinder through the transfer port (B). Since this charge enters under pressure, it also helps to push out the exhaust gases. As the piston travels down, the exhaust gases leave the cylinder and the complete cycle starts all over again. As the piston almost reaches the top of the travel, the spark plug fires, igniting the compressed air-fuel mixture. The piston continues to top dead center (TDC) and is pushed downward by the expanding gases. While the crankshaft continues to rotate, the piston moves upward, covering the transfer (B) and exhaust (A) ports. The piston compresses the new air-fuel mixture and creates a low-pressure area in the crankcase at the same time. As the piston continues to travel, it uncovers the intake port (C). A fresh air-fuel charge from the carburetor (D) is drawn into the crankcase Spark plug TWO-STROKE OPERATING PRINCIPLES (EXCEPT OPTIMAX MODELS)

4 CHAPTER ONE 2 TWO-STROKE OPERATING PRINCIPLES OPTIMAX MODELS (DIRECT INJECTION) As the piston travels downward, it uncovers the exhaust port (A) allowing the exhaust gases to leave the cylinder. A fresh air-oil charge, which has been compressed slightly in the crankcase, enters the cylinder through the transfer port (B). Since this charge enters under pressure, it also helps to push out the exhaust gases. As the piston travels down, the exhaust gases leave the cylinder and the complete cycle starts all over again. As the piston almost reaches the top of its travel, the spark plug fires, igniting the compressed air-fuel mixture. The piston continues to top dead center (TDC) and is pushed downward by the expanding gases. While the crankshaft continues to rotate, the piston moves upward, covering the transfer (B) and exhaust ports (A). The piston compresses the fresh air charge and creates a low-pressure area in the crankcase. A computer controlled electronic pump delivers a precise amount of oil into the crankcase through a dedicated passage (D). The fresh air-oil charge is drawn into the crankcase through the intake opening (C). Further upward movement of the piston closes the transfer port (B) and exhaust port (A). After both ports close, the computer controlled direct injector sprays the required amount of fuel into the combustion chamber. Spark plug Direct injector

GENERAL INFORMATION 5 1 3 4 1.in. (TPI) Diameter American Metric 60° 60° 5 MACHINE SCREWS Flat Hex Oval Filister Round 6 OPENINGS FOR TURNING TOOLS Slotted Phillips Allen Internal torx External torx

Nuts Nuts are manufactured in a variety of types and sizes. Most are hexagonal (six-sided) and fit on bolts, screws and studs with the same diameter and threads per inch. Figure 7 shows several types of nuts. The common nut is usually used with some type of lockwasher. Self-locking nuts have a nylon insert that helps prevent the nut from loosening; no lockwasher is required. Wing nuts are designed for fast removal by hand. Wing nuts are used for convenience in non-critical locations. To indicate the size of a nut, manufacturers specify the diameter of the opening and the threads per inch. This is similar to a bolt specification, but without the length di- mension. The measurement across two flats on the nut in- dicates the wrench size to use. Washers There are two basic types of washers: flat washers and lockwashers. Flat washers (Figure 8) are simple discs with a hole that fits the screw or bolt. Lockwashers are de- signed to prevent a fastener from working loose due to vi- bration, expansion and contraction. Figure 9 shows several types of lockwashers. Flat washers are often used between a lockwasher and a fastener to provide a smooth bearing surface. This allows the fastener to be turned eas- ily with a tool. Cotter Pins Cotter pins (Figure 10) are used to secure special kinds of fasteners. The threaded stud, bolt or shaft has a hole for the cotter pin; the nut or nut lock piece has projections for the cotter pin. This type of nut is called a castellated nut. Always replace the cotter pin if it is removed. Snap Rings Snap rings (Figure 11) can be an internal or external de- sign. They are used to retain components on shafts (exter- nal type) or within openings (internal type). Snap rings can be reused if they are not distorted during removal. In some applications, snap rings of varying thickness can be selected to position or control end play of parts assem- blies. LUBRICANTS Periodic lubrication ensures long service life for any type of equipment. It is especially important with marine 6 CHAPTER ONE 7 Common nut Self-locking nut Wing nut 8 9 Internal tooth Plain Folding External tooth

equipment because of exposure to salt, brackish or pol- luted water and other harsh environments. The type of lu- bricant used is just as important as the lubrication service itself; although, in an emergency, the wrong type of lubri- cant is better than none at all. The following sections de- scribe the types of lubricants most often used on marine equipment. Follow the equipment manufacturer’s recom- mendations for the lubricant types. Generally, all liquid lubricants are called oil. They may be mineral-based (including petroleum bases), natu- ral-based (vegetable and animal bases), synthetic-based or emulsions (mixtures). Grease is an oil thickened with additives, and maybe enhanced with anticorrosion, anti- oxidant and extreme pressure (EP) additives. Grease is of- ten classified by the type of thickener added; lithium and calcium soap are the most commonly used. Two-stroke Engine Oil Lubrication for a two-stroke engine is provided by oil mixed into the incoming air or air-fuel mixture. Some of the oil mist settles in the crankcase, lubricating the crank- shaft, bearings and lower end of the connecting rod. The rest of the oil enters the combustion chamber to lubricate the piston, rings and the cylinder wall. This oil is then burned with the air-fuel mixture during the combustion process. Engine oil must have several special qualities to work well in a two-stroke engine. It must mix easily and stay in suspension with gasoline. When burned, it cannot leave behind excessive deposits. It must also withstand the high operating temperatures associated with two-stroke en- gines. The National Marine Manufacturer’s Association (NMMA) has set standards for oil used in two-stroke, wa- ter-cooled engines (TC-W). This is the NMMA TC-W grade (Figure 12). It indicates the oil’s performance in the following areas: 1. Lubrication (prevention of wear and scuffing). 2. Spark plug fouling. 3. Piston ring sticking. 4. Preignition. 5. Piston varnish. 6. General engine condition (including deposits). 7. Exhaust port blockage. 8. Rust prevention. 9. Mixing ability with gasoline. In addition to oil grade, manufacturers specify the ratio of gasoline to oil required during break-in and normal en- gine operation. GENERAL INFORMATION 7 1 10 Correct installation of cotter pin 11 12