Re: Winterizing 120 hp mercruiser 1973 I/O
You will get some different advise and will have to decide for your self how to winterize.
I store my boat for the winter inside in a dry climate, also I do not use my boat all winter.
I typically put a fuel stabilizer in the tank and run the engine to make sure the fuel stabilzer is throughtout the fuel system.
I change my engine and outdrive oil. Start the engine and operate to operating temp, I slowly drizzle some engine oil down the carb and shut the engine off. Running the engine after you change the oil is good to get the new oil throughout the whole engine. A little oil down the carb is ok. I do not pull the plugs and fog the cylinders. Next spring the boat starts right up.
Store the outdrive in the down position to keep water out of the outdrive housing (if stored outside), to keep the boots in the none stretched position.
Drain all water drains typically 3 if you do not have antifreeze in the engine. One on the engine block, one on the manifold, one on the riser. Make sure you use a piece of wire and make sure no rust plugs the drain.
Then your choice if you add some antifreeze into the manifold until it drains out the outdrive. I typically do then I drain the antifreeze back out. I use old car antifreeze and run the boat on muffs before launch to make sure and get all the old antifreeze out of the system, You do not want to put this in the lake or river. I store my fuel tank full and stabilized. Make sure and turn your batteries off so they donot drain, charge the batteries every couple months to keep them charged.
I have a 140 hp mercruiser and live in climate that gets below zero.
