Small Gas Engines Fundamentals, Service, Troubleshooting, Repair, Applications
Contents CONTENT Hammers 27 Punches 28 Seal Drivers 29 Cutting and Forming Tools 29 Probe and Pickup Tools 32 Vises 32 SECTION 1 Shop Equipment, Supplies, and Safety CHAPTER 1 Safety in the Small Gas Engine Shop 15 Shop Safety 15 Proper Housekeeping 15 Hazardous Materials 16 Personal Protective Gear 17 Proper Ventilation 18 Hand Tool Safety 18 Power Tool Safety 19 Compressed Air Safety 19 Lift Properly 19 Electrical Safety 19 Engine Operating Safety 20 Be Prepared for Emergencies 20 Fire Extinguishers 20 OSHA 20 Material Safety Data Sheets 20 CHAPTER 2 Tools and Measuring Introduction 23 Hand Tools 23 Wrenches 24 Pliers 26 Screwdrivers 27 Instruments 23 Engine Tools 33 Gear and Flywheel Pullers 33 Flywheel Holders 33 Ridge Reamers 34 Ring Spreaders 34 Ring Compressors 34 G/aze Breakers and Cylinder Hones 35 Va/ve Spring Compressors 35 Lapping Sticks 36 Engine Test Instruments 36 Power Tools 37 Dr/7/s and Drill Presses 37 Bencn Grinders 37 Cleaning Tools and Equipment 38 Measuring Instruments 38 Micrometers 39 Micrometer Depth Gauges 43 Vernier Calipers 44 D/g/te/ S//'cfe Caliper 45 D/a/ Caliper 45 Telescoping Gauges 46 Sma// Ho/e Gauge 48 Thickness Gauges 48 Combination Square 49 Dial Indicator 49 Screw P/'fcn Gauge 50 CHAPTER 3 Fasteners, Sealants, and Gaskets Threaded Fasteners 53 eo/fs 54 A/ute 55 Bolt and Nut Terminology 56 Thread Designations 58 Screws 59 Tightening and Loosening Threaded Fasteners 61 Removing Broken Fasteners 61 Chasing Threads 61
Small Gas Engines Internal Thread Repair 63 Tapping New Threads 63 Threading with a Die 63 Washers 64 Electrical Test Equipment 89 Jumper Wires 89 Test Lights 90 Meters 90 Pins 64 Cotter Pins 64 Clevis Pins 65 Dowel Pins 65 Straight Pins 65 Grooved Pins 65 Taper Pins 65 Rolled Pins 65 Retaining Rings 65 Keys 66 Adhesives and Sealants 66 Thread Adhesives 66 Sealants 67 Antiseize Compounds 67 Gaskets 68 Gasket Rules 68 SECTION 2 Basics of Engine Operation CHAPTER 4 Fundamentals of Electricity, Magnetism, and Electronics 73 Introduction 73 Atoms and Electricity 73 Direct Current and Alternating Current 75 Electrical Units of Measurement 75 Ohm's Law 76 Types of Electrical Circuits 76 Series Circuit 76 Parallel Circuit 77 Series-Parallel Circuit 77 Magnetism 78 Magnetic Fields 78 Theory of Permanent Magnets 78 Magnetic Attraction and Repulsion 79 Magnetism and Electricity 80 Electrical Components 81 Electrical Wire and Connectors 81 Switches 82 Solenoids 82 Relays 82 Transformers 82 Circuit Protection Devices 85 Electronics 86 Semiconductor Diodes 86 Transistors 87 S///C0/7 Controlled Rectifiers 89 CHAPTER 5 Principles of Engine Operation, Twoand Four-Stroke Engines 95 Principles of Engine Operation 95 Gasoline Must Be Atomized 95 Explosion Must Be Contained 96 Constructing an Elementary Engine 97 Simple Engine in Operation 98 Two- and Four-Stroke Engines 99 Four-Stroke Engine 99 Intake Stroke 99 Compression Stroke 100 Power Stroke 100 Exhaust Stroke 100 Valve Timing 101 Lubrication 101 Two-Stroke Engine 101 Variations in Design 102 Principles of Two-Stroke Operation 102 Scavenging and Tuning 105 Four-Stroke Engine vs. Two-Stroke Engine 105 CHAPTER 6 Engine Components 109 Engine Components 109 Engine Block 109
Contents Crankshaft 110 Crankshaft Main Bearings 111 Crankcase Seals 112 Pistons 112 Piston Construction 113 Piston Thrust Surfaces 114 Piston Head Size 114 Piston Head Shape 114 Piston Rings 115 Piston Ring Types 115 Piston Ring Construction 118 Ring Ring Tension 118 Movement 118 Piston Pins 118 Connecting Rods and Bearings 120 Friction-Type Rod Bearings 120 Antifriction Bearings 121 Intake and Exhaust Ports 121 Ports, Reed Valves, and Rotary Poppet Valves 123 Camshafts and Gears 125 Valve Lifter or Tappet 126 Valve Train Configurations 127 Starter Assembly 127 Valves 122 Automatic Compression Release 128 Flywheel 130 CHAPTER 7 Measuring Engine Performance 133 The Engine 133 Basic Terminology 135 Engine Bore and Stroke 135 Science of Engine Energy 135 Force 136 Pressure 137 Work 137 Power 138 Torque 139 Performance 135 Measurements of Engine Performance 141 Engine Displacement 142 Compression Ratio 142 Engine Horsepower 142 Engine Torque 147 Torque and Horsepower 147 Volumetric Efficiency 148 Practical Efficiency 148 Mechanical Efficiency 149 Thermal Efficiency 149 SECTION 3 Engine Systems CHAPTER 8 Fuel Supply, Air Induction, and Emissions 153 Engine Fuels 153 Gasoline 153 Liquefied Petroleum Gas and Natural Gas Kerosene and Diesel Fuels 156 Fuel Systems 156 Fuel Tanks 156 Fuel Lines and Fittings 157 Fuel Filters 157 Fuel Pumps 157 Pressurized Fuel System 160 Vapor Return Fuel Systems 161 Air Induction Systems 161 Air Cleaners and Air Filters 162 Crankcase Breathers 165 Mufflers 166 Emissions 167 Emission Control Regulations 167 CHAPTER 9 Carburetion 173 Principles of Carburetion 173 Air-Fuel Mixture 174 Carburetor Pressure Differences 174 Types of Carburetors 176 Float-Type Carburetors 176 Diaphragm-Type Vacuum Carburetors 185 Primers 186 Carburetors 182 Manual Throttle Controls 186
Small Gas Engines Governor Throttle Controls 187 What an Engine Types Governor Features 192 of Governors 188 CHAPTER 10 Ignition Systems 195 Governor Does 187 Basic Ignition System Operation 195 Ignition System Components 196 Ignition Coil 197 SparkPlugs 197 Spark Plug Wire 200 Switching Devices 200 Magneto Ignition Systems 201 Operation of Capacitive Discharge Ignition (CDI) System 202 Operation of Transistor-Controlled Ignition (TCI) System 203 Operation of the Mechanical Breaker Point Ignition (MB!) System 205 Magneto Ignition Systems for Two-Cylinder Engines 208 Battery Ignition Systems 208 Auto-Transformer-Type Ignition Coil 210 The Lead-Acid Battery 210 The Discharging/Charging Cycle 211 CHAPTER 11 Lubrication Systems 215 Principles of Lubrication 215 Friction 215 Qualities of Lubricating Oil 216 Permits Easy Starting 216 Lubricates and Prevents Wear 216 Protects Against Rust and Corrosion 217 Keeps Engine Parts Clean 217 Cools Engine Parts 218 Seals Combustion Pressures 218 Prevents Foaming 218 Aids Fuel Economy 218 Oil Specifications 218 SAE Viscosity Grade 218 API Engine Oil Service Classification 219 Selecting the Proper Engine Oil 220 Engine Lubrication Systems 221 Two-Cycle Engine Lubrication 221 Four-Cycle Engine Lubrication 222 Oil Filter Systems 225 Low-Oil Warning and Shutdown Systems (LOS) 227 CHAPTER 12 Cooling Systems 231 Principles of Engine Cooling 231 Air Cooling 232 Liquid Cooling 233 Pressurized Cooling Systems 233 Outboard Engine Cooling Systems 235 SECTION 4 Engine Service CHAPTER 13 Preventive Maintenance and Troubleshooting 243 Preventive Maintenance 243 Engine Cleaning 243 Checking Oil Level and Condition 244 Changing Oil 245 Lubricating Cables and Linkage 246 Spark Plug Service 247 Air Cleaner Service 248 Crankcase Breather Service 249 Muffler Service 250 Battery Service 251 Pressurized Liquid Cooling System Service 252 Maintaining Outboard Cooling Systems 252 Storing an Engine 253 Systematic Troubleshooting 254 Check the Easiest Things First 254 Verify the Fundamental Operating Requirements 254 Checking RPM 255 Testing Compression 256 Testing Differential Pressure 257 Service Information 258 Engine Identification 258
Contents CHAPTER 14 Fuel System Service 265 Troubleshooting the Fuel System 265 Hard Starts 265 Checking Air-Fuel Mixture 266 Checking Gravity-Fed Fuel Supply 267 Checking a Fuel Pump 268 Other Checks 268 Carburetor Adjustments 268 High Speed and Idle Mixture Adjustment 269 Carburetor Overhaul 269 Carburetor Removal 270 Carburetor Disassembly 270 Diaphragm Carburetor Disassembly 273 Cleaning the Carburetor 274 Inspecting Float Carburetor Parts 274 Assembling Float-Type Carburetors 276 Inspecting Diaphragm Carburetor Parts 278 Assembling a Diaphragm Carburetor 279 Engine Governor Service 280 Resetting a Centrifugal Governor System 280 Governor Adjustment 281 CHAPTER 15 Ignition and Electrical System Service 291 Ignition System Service 291 Performing a Spark Test 291 SparkPlugs 292 Magneto System Service 295 Servicing Battery Ignition Systems 297 Electrical System Service 297 Batteries 297 Wiring 302 Ammeters 302 Switches and Solenoids 302 Checking the Charging and Starting System Circuits 302 CHAPTER 16 Engine Disassembly and Inspection 311 Introduction 311 Engine Inspection 312 Engine Removal 313 Engine Disassembly 314 Removal of Exterior Engine Components 314 Organizing the Job 317 Disassembling the Engine's Mechanical Systems 318 Removing Engine 324 Removing the Valve Assemblies on an Overhead Valve Engine 325 CHAPTER 17 the Valve Assemblies on an L-Head Cylinder, Crankshaft, and Piston Service 329 Cylinder Reconditioning 329 Cylinder Inspection 329 Cylinder Measurement 330 Reboring the Cylinder 331 Honing the Cylinder 332 Crankshaft and Main Bearing Service 333 Inspecting the Crankshaft 334 Inspecting the Main Bearings 335 Piston Assembly Service 336 Checking Piston Clearance 337 Ring Side Clearance 337 Removing Piston Pins 338 Measuring Piston Pins and Bosses 339 Inspecting Connecting Rods 339 CHAPTER 18 Camshaft and Valve Train Service 341 Introduction 341 Camshaft Service 341 Valve Service 343 Inspecting Valves and Seats 343 Inspecting Valve Springs 343 Valve Guides 343 Refacing Valves 346 Valve Lifter Service 346 Valve Seat Service 348 Lapping Valves 350 Adjusting Valve Lifter-to-Stem Clearance 353 Servicing Overhead Valves, Seats, and Guides 354
Small Gas Engines CHAPTER 19 Engine Reassembly and Break-In 357 Introduction 357 Reinstalling Internal Engine Components 357 Installing Valves (L-Head Engine) 358 Installing the Crankshaft, Camshaft, and Governor Gear 358 Installing the Piston and Rod Assembly 359 Installing Overhead Valves 364 Installing the Cylinder Head 365 Installing the Crankcase Breather and Valve Cover 366 Adjusting Crankshaft Endplay and Installing the Crankcase Cover 367 Reinstalling External Engine Components 367 Engine Break-In 368 SECTION 5 Applications CHAPTER 20 Lawn and Brush Equipment 373 Working Safely 373 Lawn Mowers 375 Rotary and Reel Mowers 375 Push-Type and Self-Propelled Mowers 376 Optional Features 376 Engine Starting 377 Minor Checks 379 General Maintenance 379 Chain Saws 382 Chain Saw Designs 382 Safety Features 382 Rules for Safe Operation 385 Chain Saw Maintenance 385 String Trimmers and Brushcutters 388 Design Features 388 Operator Safety 390 Starting and Safe Operation 391 String Trimmer and Brushcutter Maintenance 394 Edger/Trimmers 396 Edger/Trimmer Features 397 Safety Features and Adjustments 397 Rules for Safe Operation 399 Edger/Trimmer Edger/Trimmer Storage 400 CHAPTER 21 Maintenance 400 Lawn and Garden Tractors 403 Tractor Safety 403 Protect Children 404 Protective Clothing 404 Operating a Tractor Safely 404 Transporting a Tractor 405 Tractor Uses 405 Mowing and Mulching 405 Leaf Collecting 407 Plowing, Throwing, and Blowing Snow 407 Preparing Soil for Planting 409 Hauling a Trailer 409 Rotary Broom Sweeping 409 Engine Components 410 Chassis and Steering 410 Transmissions 412 Variable-Speed Hydrostatic Transmissions 415 Transmission 414 Electrical Safety Systems 421 Safety Interlocks 422 Electric Start Systems 423 Recoil Start System 425 Testing Procedure for Operator Presence System (Safety Seat) 426 Circuits for Study 427 General Maintenance 427 Engine Lubrication 434 Optional Oil Accessories 434 Air Filter 434 Mufflers 434 Engine Cleaning 435 Radiator Cleaning 435
Contents Battery Maintenance 435 Sharpening and Balancing Mower Blades 435 Fueling and Refueling 436 Storing a Tractor 436 Removing a Tractor from Storage 436 CHAPTER 22 Snow Throwers 439 Operating Safely 439 Machine Types and Features 440 Small Snow Throwers 440 Midsize Snow Throwers 441 Heavy-Duty Snow Throwers 442 Engine Controls 443 Operator Presence Controls 443 Electric Start Systems 445 Drive Systems 445 Skid Shoes 449 Snow Thrower Operation 450 Engine Starting 450 Snow Throwing 451 General Maintenance 451 Preventing Freeze-Up 451 Sen/icing Augers 451 Lubrication 452 Off-Season Storage 453 Starting after Storage 453 CHAPTER 23 Personal Watercraft 457 Introduction 457 Identification Numbers and Placards 458 Types of PWC 458 PWC Main Components and Parts 459 PWC Engines 462 Basic Engine Parts 462 Engine Cooling System 466 Jet Pump Propulsion System 466 New Engine Break-In 469 General Maintenance 469 Fuel Filter 469 Fuel Filter Screens 470 Fuel Vent Check Valve 470 Sediment Bowl 470 Oil Filter and Oil Filter Screen 470 Oil Pump Bleeding 471 Carburetors 471 Cooling System Flushing 473 Jet Pump Water Inlet Screen 474 External Lubrication Points 474 Transporting PWC 475 Towing PWC to Shore 476 PWC Storage 476 CHAPTER 24 Career Opportunities and Certification 481 Career Opportunities in the Small Gas Engine Field 481 Engine Service Technician 481 Service Manager 482 Sales Manager 482 General Manager 482 Manufacturer's Technician 482 Service Representative 483 Engineer 483 Executive 483 Entrepreneur 483 Teacher 484 Certification 484 Why Get Certified? 484 W/?af /s on a Certification Test? 484 Wno Can Ta/ce fhe Test? 484 Succeeding in the Workplace 485 Maintain a Professional Appearance 485 Work Habits 485 Time Management 485 Professional Behavior 486 Decision Making and Problem Solving 486 Communication Skills 486 Customer Relations Skills 486 Ethical Workplace Behavior 487 Interpersonal Skills 487 Belonging to Organizations 487 Appendix 489 Glossary 501 Index 522