The John Deere 6068TFM is a 6-cylinder marine engine, capable of 201 horsepower at 2500 rpm. John Deere manufactures many diesel engines for a range of applications. All engines will eventually suffer from wear. Run through a troubleshooting and preventive maintenance checklist before calling a John Deere marine mechanic for a service. Make sure to cover the basics: oil and coolant levels, battery inspections, engine leaks and clogged fuel filters.
Check for sufficient levels of oil if the engine cranks but has a hard time starting. Turn the engine off. Look on either the left or right side of the engine for the oil filler cap and dipstick. Remove the dipstick and wipe clean before reinserting into the engine. Wait a few moments then remove the dipstick and check the oil level. Fill the system with a John Deere recommended seasonal viscosity grade oil as necessary. Do not fill above the top mark on the dipstick. Oil levels within the crosshatch pattern on the dipstick is acceptable. The oil should be checked daily.
Check and fill the engine coolant if needed. Check the coolant in the engine top tank when cool. Use a John Deere recommended coolant to fill the tank to the bottom of the filler neck. Check the coolant level at least once a day during operational seasons.
Inspect the engine compartment for oil or coolant leaks, worn drive belts, loose connections and trash buildup. Remove any trash that may have accumulated around the engine and have a qualified John Deere marine mechanic inspect further if you notice leakage. A small amount of leakage is normal as the engine cools and components contract. Anything more than a a few drops here and there, should be checked into.
Check the fuel filter for water or clogs. Twist the drain plug at the very bottom of the fuel filter one or two times. Loosen the air bleed plug (black button) near the top of the filter two full turns and allow water to drain from the bottom until fuel starts to drain out. Tighten the plug once fuel starts to drain. Prime the filter to bleed all air from the fuel system. The primer operating lever is just to the right of the filter. Prime until the fuel flow is free of bubbles. Tighten the air bleed plug.
Check the battery electrolyte level and refill as needed. Use distilled water to fill each battery cell to the bottom of the filler neck. Coat the battery terminals and connectors with a mixture of petroleum jelly and baking soda to prevent corrosion.
