Marine Technology
Contents
1. Marine Technology Backstay Mainsail Shroud or stay Boom _ Tiller Chainplate _ Hull Waterline Review The Sailboat FT J y gt PFT 3 J lax aT Marine anrnhnninox7 VU Ia N a Yidi LAY L M MGL CL L AY AL 11 X 2 NA N A A A A LN OJ e Compression Testing amp Other 4 Stroke Considerations AM PM e Sailboat Sails Quiz AM PM e Fuel Ratios 2 Stroke Math AM PM e Compression Testing AM PM e Web Search Old Outboard Motors In the News e Ferry Disaster Update e Missing Jet Update e Boston Strong e Corvette Sink Hole Update Warm up Question 1 e You notice that the ground wire to your gasoline tank has corroded at the connection and as a consequence is barely attached What should you do A Ignore the problem because it does not matter O B Cut back the wire replace the connector and reattach o C Inspect and clean ground wire connections at both ends to ensure proper grounding of the tank o D Both B C o Answer Both B amp C Grounded Fuel Tank WIRE TO GROUND TANK GROUND TANK GAGE SENDER Warm up Question 2 e Your runabout s hydraulic steering wheel is making a clicking sound and the outboard does not always move when turning the wheel What may be a possible reason o A The propeller has been dinged o B Steering has air in the system o C The outboard is expe2. riencing cavitation o D None of the above o Answer B Compression Testing e To test compression bring engine up to normal operating temperature Testing Annually is a great idea so that you can detect early signs of failure O Find a potential problem early and save money o Example gummed up piston rings can be readily fixed using a de carbonizing solvent e The service manual will provide the proper specifications for compression Compression Testing Benchmarks e As it is important to be within the manufacturer s recommendations it is EQUALLY important to establish a benchmark for future diagnostics o If there is more than a 15 PSI difference drop from the benchmark be concerned and proactive Also important is the variation between cylinders o Ensure that there is not more than a 15 PSI difference between cylinders 0 y 34 14 ceron tt CHARS 5 L LS E K L S PA HEE ie Steps for Compression Testing VA TN f 1 SS e 1 Disable the engine s ignition system o Unplug the gang plug or engine kill switch O Ensure that there is no spark at the plugs or wires e 2 Remove the engine s spark plugs o Inspect each plug to diagnose possible problems e 3 Thread the compression tester into cylinder 1 and zero out the guage e 4 Open the engines throttle or fast idle e 5 Crank the engine the same number of times for each cylinder you test e 6 Record
3. your readings place in engine s log book y W J Blow by and Low Compression Low compression blow by around piston rings at cylinder wal worn ring grooves wavy ring groove or wavy piston ring side walls due to insufficient gap in ring ends carbon accumulation Other Considerations e Remember that an engine that has been in storage for some time may have relaxed o Run engine for several extended periods prior to use o If reading is low squirt some shop oil into suspect cylinder to Wet Test x If compression improves rings may be gummed up x Us a decarbonizing spray to dissolve the gum and re test o Spray into air intake while engine is running o If the Wet Test does not improve compression then internal problems are probable x Worn rings x Worn cylinder lining Gap the Spark Plugs amp Run e Once compression testing is complete o Replace the spark plugs with new plugs if necessary x If the plugs require GAPPING consult owner s manual for guage x Us a feeler guage to set the proper gap Plug Diagnostics 1 2 3 4 Oil Fouled Oil Fouled Carbon Fouled Too Cold 5 B 8 Too Cold Cold or Rich Cold or Rich Cold or Rich But OK But OK rni MN 1 0 A k 2 TY IA MM S FIN 1 11 CUIII JI CS S D E AA LZ A U 7 A 0 2 a PR lf W W W y
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