7 Outboard Engines and Stern Drives 67 COURSE LESSON TITLE PRESENTATION TIME PRESENTATION METHOD MATERIALS REQUIRED Chapter 7 Outboard Engines and Drives, and Stern Drives 2 hours Participative Lecture Ch7 PPT slides, computer, projector Objectives Topics Resources & Notes GAIN ATTENTION Review homework from chapter 6 Slide 1 OBJECTIVE PRESENTATION Outboard Systems Upon completion of this chapter, the student will have: 1. a good understanding of the component parts of the outboard marine engine and how these parts work together to propel the boat through the water 2. knowledge of the fuel, lubrication, cooling, exhaust, ignition and electrical systems needed for the outboard engine to function properly 3. an understanding of the stern drive that is used in inboard/outboard operation 1. Crankcase Similar to conventional crankcase, but designed to work vertically Different bearing design Dry sump lubrication 2. Crankshaft Bearings are designed for vertical operation Relies on mist lubrication 3. Pistons Long skirt to valve intake and exhaust ports No oil control grooves Domed head to scavenge cylinder gases 4. Carburetion Multiple carburetors are common Individual carburetors are simpler than inboard engine designs 5. Lubrication Oil mist lubrication o Usually requires oil and fuel to be premixed o Can be injected from oil reservoir No sump required No oil cooling benefit 6. Cooling and Exhaust Cooling derived from impeller pump in lower unit Most water cools the exhaust Exhaust is vented through the propeller hub Slide 2 Slides 3 4 Slide 5 Slide 6 Slide 7 Slide 8 Slide 9
68 7 Outboard Engines and Stern Drives Objectives Topics Resources & Notes 7. Ignition Magneto o Coil energy is provided by magnet in engine flywheel Distributor / breaker point o Same as inboard engines Solid state Slide 10 I/O Drive Systems 8. I/O Characteristics Slides 11 12 Inboard engine Outboard drive system Generally pierces the transom, not the hull 9. Tilt and Trim Systems Slide 13 Mechanical on small drives Hydroelectric on larger systems 10. Routine Maintenance Service twice per season o Check lower unit lubricant and replace if necessary Replace zincs as needed (when >50% consumed) Check boots and seals for cracks Slide 14 Winter Storage Prevent freezing Slide 15 Check and replace lubricant as needed Replace zincs as needed (when >50% consumed) Warm the engine, then change the oil Run potable antifreeze through the raw water system Check boots and seals for cracks Paint housing if needed Spring Service Should not be necessary! Slide 16 EXERCISE SUMMARY HOMEWORK Complete homework questions for Chapter 7
7 Outboard Engines and Stern Drives 69 Homework Questions 1. The three major subassemblies of the outboard marine engine are the: a. power head, intermediate housing, and the drive housing. b. lower unit, drive housing, and the intermediate housing. c. power head, lower unit, and intermediate housing. d. lower unit, outer housing, and power head. 2. The subassembly of the outboard engine that provides a means for attaching the engine to the boat is the: a. lower unit. b. intermediate housing. c. power head. d. outer housing. 3. The subassembly of the outboard engine that operates under the water is the: a. power head. b. drive housing. c. intermediate housing. d. lower unit. 4. The subassembly of the outboard engine that usually contains the transmission for forward and reverse thrust as well as a neutral gear is the: a. power head. b. drive housing. c. intermediate housing. d. lower unit. 5. The two basic configurations for outboard engines are: a. 2-cycle and 4-cycle. b. saltwater and fresh water. c. portable and fixed mounted. d. propeller driven and jet driven. 6. The crankcase design for outboard engines differs from the inboard engine in that the outboard crankcase operates: a. with greater torque. b. in a vertical mode. c. without lubrication. d. without main bearings. 7. A 2-cycle outboard will generally have more per pound of weight than the four stroke outboard. a. parts. b. torque. c. compression. d. power. 8. A 2-cycle outboard engine: a. has exhaust valves in the power head. b. has exhaust ports in the cylinder walls. c. does not have piston rings. d. does not require lubrication.
70 7 Outboard Engines and Stern Drives 9. The purpose of the carburetor used with outboard engines is to: a. control carbon in the engine. b. provide correct fuel and air mixture. c. pump fuel from the fuel tank. d. provide timing to the engine. 10. Carburetors used on outboard engines are generally of the: a. single barrel design. b. two barrel design. c. four barrel design. d. multi-port design. 11. Fuel used in 2-cycle gasoline outboards must be mixed with: a. additives. b. alcohol. c. ethanol. d. oil. 12. The three basic ignition systems currently in use for outboard engines are: a. solid state, magneto, and permanent magnet. b. solid state, distributor/breaker point, and permanent magnet. c. solid state, magneto, and distributor/breaker point. d. distributor/breaker point, magneto, and permanent magnet. 13. Lubrication for 4-cycle outboard engines requires: a. oil to be mixed with the fuel. b. a separate oil reservoir. c. wet-sump operation. d. a simple oil pan reservoir. 14. In an outboard mechanical shifting transmission the engagement between the clutch and forward or reverse gear results in: a. positive and smooth load transfer. b. time lag between forward and reverse motion. c. slippage or power loss in the transmission. d. sudden shock and impact loads in the transmission. 15. A major difference between outboard engine drive systems and the inboard/outboard stern drive system is stern drives: a. are not attached to a boat s transom. b. have no reverse capability. c. are permanently attached through an opening in the transom. d. have no tilt capability. 16. The two factors that affect the trim of a boat powered by an outboard engine are the: a. horsepower of the engine and the diameter of the propeller. b. diameter of the propeller and the loading of the boat. c. horsepower of the engine and the tilt of the outboard motor. d. loading of the boat and the tilt of the outboard motor.
7 Outboard Engines and Stern Drives 71 17. As a minimum, stern drives and the lower unit of outboard engines should be checked and serviced: a. only at the start of the boating season. b. twice during the boating season. c. only at the close of the boating season. d. once every 30 days. 18. Sacrificial zinc anodes should be replaced: a. if they are more than 50% consumed. b. only at the start of the boating season. c. when 75% consumed. d. only when laying-up the boat. 19. What steps should be taken if moisture or contaminants are found in the lubricant of the lower unit or stern drive? a. Find the cause, make repairs, and replace the lubricant. b. Flush the lower unit or stern drive and replace the lubricant. c. Add more lubricant to force the moisture or contaminants out. d. Drain and flush the lower unit or stern drive and add more lubricant.
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