Corsica River Marine Surveys

Annapolis, Maryland, USA
Serving Maryland, Delaware, Virginia, New Jersey, North Carolina & Central Florida

Travis L. Palmer, SAMS® AMS®, ABYC
Principal Marine Surveyor

Cell: 410-739-7097

Pre-Purchase Marine Surveys • Marine & Cargo Surveys • Insurance Damage Claims • Vessel Appraisal • Project Management and Oversight • Expert Witness • Damage Surveys • Insurance Survey

Engine Winterization for Fuel Injected inboard engines & fresh water systems

We all know the dreaded winter is coming. Take some time to read this article to familiarize yourself with the winterization process it’s not as hard as it sounds!

Step 1: Stabilize fuel system

Corsica River Marine Surveys - Engine WinterizationFuel Storage Mixture

  • Prepare the storage mixture: using a portable, outboard engine fuel tank, add: Fresh fuel (enough to run engine 15 minutes) two-cycle motor oil (50:1 ratio, gas to oil) fuel stabilizer, per manufacturer’s instructions. DANGER! Fuel and vapors will be present during procedure, provide ventilation and eliminate spark/flame sources.
  • Disconnect the fuel line at the inlet fitting of the engine’s fuel pump. Connect a line from the portable tank (with storage mixture) to the fuel pump inlet. CAUTION! Engine must be run to complete process. Take precautions to ensure safety and prevent engine damage:
  • Run engine with drive out of gear and in trim position
  • Boat must be properly supported
  • Must have adequate cooling water, monitor engine temperature gauge.
  • Do not run fuel pumps dry
  • Run the engine on the storage mixture for five minutes at 1500 RPM. This will ensure that all fuel system and internal engine components are protected.
  • Reduce the engine speed to idle and stop the engine.
  • Leave disconnected fuel line in gas canister.
  • Fill gas tanks to 95% full to limit air space in tanks and reduce internal condensation. Add proper amount of stabilizer to filled fuel tanks

Step 2: Change fuel/water separator canister. Drain and change oil and oil filter. Change transmission/outdrive oils.

  • Be sure to fill the new fuel/water separator filter with the fuel stabilizer “cocktail” used above.

Step 3: Drain the block and manifolds for any cooling water. Open up and completely drain the block!

Corsica River Marine Surveys - Engine WinterizationStep 4: Circulate antifreeze throughout the block.

  • Introduce and circulate marine antifreeze into engine block
  • If boat is equipped with outdrives. Use outdrive muffs to circulate antifreeze into the engine block. Start the engine and let it reach operating temperature so the thermostat opens up and the antifreeze can circulate correctly out of the exhaust. You should see the pink stuff coming out of the exhaust.
  • The engine should be running off of the gas can mixture mentioned above.

Step 5: Trim drives all the way down to protect the stainless hydraulics and bellows

Step 6: Remove batteries and store in a cool dry place

Step 7: Drain holding tank and add a gallon of bleach to tank

Step 8: Run fresh water system until dry. Add 7 gallons of antifreeze to tank and then run until all faucets and toilets spit out pink.

NOTE: MerCruiser and Volvo Penta do not recommend fogging EFI or MPI engines if layup period is not significant (greater than 6 months).

Author: Principal Marine Surveyor
Travis Palmer,