Steve D'Antonio offers services for boat owners and buyers through Steve D'Antonio Marine Consulting (www.stevedmarineconsulting.com).
During the Pre-Purchase Inspection, Your Mechanic Should:**
• Ensure that the wet exhaust system has the specified drop or slope to the muffler and rise before the discharge.
• Determine that the cables used for the positive and negative electrical supply to the starter are the correct size.
• Inspect the motor mounts to make sure that they're tight, secure, and not overextended.
• Determine that the installation meets the manufacturer's specifications, then ensure that the engine doesn't overheat and achieves the rated wide-open-throttle rpm by operating it under way at 80-percent rpm for a minimum of one hour and at 100-percent throttle for 10 minutes.
• Check the cylinder compression, if it's a used engine.
• Test the exhaust-system components for proper temperature while
under way. No part of an exposed exhaust component should exceed 200 F, and the water-cooled portions of the exhaust, and especially the hose, typically shouldn't exceed 150 F.
• Check during the sea trial that the engine-compartment temperature doesn't measure 30 F above the cabin's air temperature. During the sea trial, except for observations, the engine compartment or box should be closed. The mechanic tests by placing a remote thermometer in the compartment adjacent to the engine air intake. If the temperature difference exceeds 30 degrees, the engine requires additional ventilation.
• Test the exhaust-gas back pressure during the sea trial.
• Send samples of the crankcase oil, transmission fluid, and coolant for laboratory analysis. The value of fluid analysis can't be overstated, and it's a bargain, with analysis kits costing about $30 each. S.D'A.