How to Winterize Mercruiser 5.7 | Winterization Steps 2023

Last Updated on August 16, 2023 by Jisan

Assuming you have a 5.7 liter Mercruiser engine in a boat: 1) Remove the spark plugs and spray fogging oil into each cylinder. Re-install the plugs.

2) Disconnect the battery terminals. 3) Drain the block by removing the drain plug at the lowest point of the engine. If your model has an oil cooler, also drain that by disconnecting the hoses at the fittings on either side of the cooler.

4) Remove any raw water impellers or sea strainer baskets and store them in a dry, safe place until spring. 5) Fog all exposed carburetor parts with fogging oil designed for marine engines; this will help prevent corrosion over winter.

  • Remove the engine cover and disconnect the negative battery cable
  • Loosen the clamps and remove the hose from the water pump inlet
  • Insert a garden hose into the water pump inlet and secure it with a clamp
  • Turn on the water and run it through the engine for several minutes to flush out any salt or debris
  • Reconnect the hose to the water pump inlet and tighten the clamps
  • Replace the engine cover and reconnect the negative battery cable
How to Winterize Mercruiser 5.7
How to Winterize Mercruiser 5.7 | Winterization Steps 2023 2


How Much Antifreeze Do You Need to Winterize a 5.7 Mercruiser?

It’s important to know how much antifreeze you need to winterize your 5.7 MerCruiser engine. Too little antifreeze and your engine could freeze and crack, while too much can cause corrosion and damage to seals and gaskets. The ideal ratio is 50/50 coolant and distilled water.

To calculate the amount of antifreeze you’ll need, first find out how many quarts your MerCruiser holds. Then mix equal parts of coolant and distilled water until you’ve reach the desired volume. For example, if your MerCruiser holds 4 quarts, you would mix 2 quarts of each fluid.

Where are the Drain Plugs Located on a 5.7 Mercruiser?

There are two drain plugs located on a 5.7 MerCruiser. One is located at the front of the engine, near the water pump, and the other is located at the rear of the engine, near the oil filter.

How Many Gallons of Antifreeze Do I Need to Winterize My Mercruiser?

If you’re winterizing your MerCruiser, you’ll need at least 3 gallons of antifreeze. This will ensure that your engine and other components are protected from the cold weather and freezing temperatures. You may need more or less depending on the size of your engine, so it’s always best to consult your owner’s manual for specific instructions.

What Do I Need to Winterize My Mercruiser?

Assuming you have a MerCruiser inboard/outboard engine, here are the basic steps for winterizing: 1. Change the engine oil and filter. This will help remove any water or debris that may have accumulated over the season.

2. Add fuel stabilizer to your gas tank to help keep the fuel fresh over the winter months. 3. Fog the engine by spraying fogging oil into the carburetor while the engine is running at low speed. This will help prevent corrosion and build-up inside the engine during storage.

4. Drain all of the water out of your boat’s hull, including the bilge, livewells, and anything else that holds water. Remove any drain plugs so that any remaining water can escape. 5a.

If you have an older boat with an exposed prop shaft, it’s a good idea to remove it and store it indoors for safekeeping (you can also put some grease on it to help protect against rust). 5b. For boats with enclosed drives (such as an Alpha drive), simply disconnect the drive from the transom and remove any debris from inside before storing indoors (again, putting some grease on exposed parts will help prevent rust).

Mercruiser 305,350 5.0,5.7 V8 Winterization in 5 Minutes.


This blog post provides helpful tips for winterizing your Mercruiser 5.7 engine. By following these simple steps, you can ensure that your engine will be protected from the cold weather and will be ready to go when spring arrives.

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