Mercruiser 3.0 winterize

[navymike]

Good morning I need some help as far as what and where are the plugs to pull on my 1989 mercruiser block to drain the water at the lowest point and what type of antifreeze to use to pour back down the block etc...I'm new to this boat stuff and don't want to crack my block..is there certain hoses that need to come off as well and pour antifreeze back towards the block..just need help

 

[Bt Doctur]

there is 1 plug on the port side of the block just above the oil pan, remove it and probe the opening to make sure it drains. just above that on the bottom of the manifold is another brass plug. remove it and probe the opening to drain the manifold and riser.
should you desire to add A/F you must use non-toxic if near any water. remove the large hose from the therm housing and pour the af in until it comes out the housing, reattach hose.
remove small manifold hose from therm housing and pour a/f in until you see it come out the exaust ports on the drive.
lower the drive all the way, then hit the up button to relieve any pressure, remove battery and cover.
Grab a beer, start a fire, and enjoy the winter

 

[navymike]

Is the general rule of thumb to use A/f..I live around houston area..

 

[Bt Doctur]

most blocks are cast iron and will release some scale if left dry. you usually introduce A/F to keep the blocks wet to prevent this and to provide some lubrication to the circ pump on the engine.
Air dosent freeze either.

 

[GA_Boater]

Is the general rule of thumb to use A/f..I live around houston area..

I also had a Mercruiser when I lived outside of Houston. I just drained everything and didn't use antifreeze. It normally doesn't get cold enough. It happens occasionally, but I learned how to do a 10 minute procedure when I pulled the boat out and 10 minutes before putting her back in. I boated all year.

 

[navymike]

I have only found one drain plug..is there more than one and what is a good way of pouring the AF down into the block

 

[airshot]

Second post said there were two drain plugs one on the block down low and another up under the manifold near the rear. BOTH must be drained. Just remove the thermostat housing and pop it off, remove the t-stat and pour. If you are going to take your boat to the lake in the spring to get it ready the you have to use RV antifreeze (pink stuff) but if you do like I do and do all the test running and service at home in my stone driveway then I use regular automotive antifreeze for the rust prevention abilities. DO NOT put the green antifreeze into the lake as it will kill the fish and other animals, and the DNR people will fine you heavily. Drain both plugs and install antifreeze in t-stat opening, takes a little less than two gallons. ( don't forget to reinstall the drain plugs or your antifreeze will be inside your bilge)

 

[JimS123]

Mine has a 3rd brass drain plug on the manifold elbow. Better look for that one to.

Best thing would be to contact Mercruiser and buy or download a free Owner's manual. It has pictures for winterizing that takes out all the guesswork.

 

[airshot]

Mine has a 3rd brass drain plug on the manifold elbow. Better look for that one to.

Best thing would be to contact Mercruiser and buy or download a free Owner's manual. It has pictures for winterizing that takes out all the guesswork.

Good point...anyone owning one of these or has any hope of doing their own maintenance seriously needs one!!!

 

[wahlejim]

I know a couple of boat owners near Houston and they don't winterize. In the rare event that the temp drops below freezing, they just put a utility light in their engine compartment. When your average temperatures are in the 50s in January, I wouldn't be too worried about AF. It takes more than one overnight low in the 30s to freeze an engine block. If it helps you sleep at night you can drain the plugs, but I think that AF is way overboard for your neck of the woods.

 

[JimS123]

The Fall, 2015 BoatUS publication had an article on boat winterizing. As usual, they also have a slew of pictures depicting accidents and how to avoid them.

They specifically recommend against putting lights and bulbs in engine compartments because of the danger of fire.