Winterizing

[area51]

I have a 1987 Montego 2757 with twin Mercruiser 470s with Alpha One outdrives. I'm not going to do oil changes this year because the boat was barely used. The engines have closed cooling systems. I plan to drain the heat exchangers, but I don't know what else needs to be drained. Are there water drains in the outdrives or any other place?

[km1125]

Are you asking just about the engines, or the whole boat?

If you're not going to use any antifreeze on the engines, then also make sure you drain the raw water pump and strainer, as well as any of the raw water hoses that dip down and might hold water. You also need to make sure that the manifolds are part of the closed system, or you need to drain them too. Also you probably need to drain the risers, whether or not the manifolds are part of the closed cooling system. What about mufflers? Do you have water-lift type? If so, those probably need to be drained too.

For the rest of the boat, the potable water system, water heater, heads and any HVAC components. If you have a washdown system that also needs to be drained. You also should drain or put PG antifreeze in the shower sumps. On the potable water, don't forget about the city water inlet if you have one.

[Viper]

Providing there are no obstructions in the drive's raw water circuit, it should self drain as long as it's in the full down position. Having said that, the raw water pump is in the drive and on the off chance that some water might get trapped in the pump, I would run antifreeze directly through the drive with muffs.

If you're talking just the engine, KM mentioned a couple of things to look out for. The 470 should have a closed cooled manifold. You'll also want to drain any oil coolers on the engine. Some Merc applications also have check valves in the raw water circuit usually behind the engine which must be emptied. If you haven't considered it, it's highly recommended you run winterizing antifreeze through the engine in case you miss something you may not be aware of.

Very important, do you have alternators? If not, you have raw water cooled regulators. Even with an aftermarket alternator install, the water cooled regulators might still be there. Again, this is yet another reason to run antifreeze through the engine when winterizing.

BTW, there won't be a strainer or mufflers in an IO application unless it's been modified for some reason. In a normal IO application, it'll draw raw water through the drive save for some high performance installs that can draw through the hull/seacock, this does not include Alpha drives. The IO will also exhaust under water so no need for a muffler.

[tomschauer]

I had a 2757. Loved that boat.
As Viper Mentioned, you should run some pink stuff through earmuffs to make sure the heat exchanger, power steering cooler and voltage regulator are protected.
The engines blocks should have antifreeze in them. May want to verify it has the protection for the Michigan winter.

[area51]

Good advice, thanks. I am just asking about the engines; everything else is squared away. I usually have a mechanic do the oil changes and winterizing on the engines and outdrives, but this year I just need to take care of the seawater system, so I figured I could do it myself. I checked the antifreeze and it's good for winter on the hard by Lake Superior. I'll get some muffs and some of the pink stuff and run it through.


Thanks!