1GM winterize in Texas

[frankfurder]

I have had my 25d since 1996 and either use the drain plug to drain engine water or run antifreeze thru the system.

Here on Lake Grapevine, the water temps stay in the 40's but air temp can be below freezing for several days or sometimes a week or two.

My question is which option is most effective against major freezing damage, I have had none in 22 years so both seem to work;

1. Unless I run antifreeze thru after the engine has reached operating temp. I assume the thermostat will not be open, is the cylinder head protected? One school of thought is that after the last outing where the thermostat opened, once the engine is shut off, water will drain out of the cylinder into the exhaust, eliminating the need to reach operating temp for adding anti freeze at a later date?

2. if I use the drain plug after the engine has sat idle will there still be water in the cylinder head without removing the thermostat (which I have read about in some of the northeast winterization processes)
My Yanmar manual recommends using the drain plug to drain the water after the engine has cooled off.

I think using the drain plug on a cold engine is sound, just seeking feedback, Thanks!

[Steve Laume]

Is this a raw water cooled engine?

If it is raw water cooled then it seems as if the thermostat would need to be opened. I really don't know much about those engines.

If there is a heat exchanger, then the water just needs to be drained or antifreeze run through the system. The engine is not the only thing you are trying to protect. Just draining the engine will not protect the heat exchanger, waterlift muffler and any hoses in the system. Running antifreeze through the system has always worked well for me and it seems like an easier way to go than trying to be sure you have removed all the drain plugs.

It is not just the engine you need to be concerned about, Steve.

[sgbernd]

I assume you leave the boat in the water over the winter. If so, it doesn't matter what you do as the lake doesn't freeze. I had my boat on Lake Texoma (at the time with a raw water cooled MD7) for some years and never worried about it. The lake is a heat sink, and the propeller and shaft will hold the engine near the lake temperature. So even though the air temperature gets below freezing, they engine block will not.

If you move the boat to the hard for the winter, then it is at risk so you need to either drain the engine block or insert antifreeze as you discussed.

-sgb

[Joe Myerson]

Do you keep your boat in the water throughout the year?

If not, you can remove your thermostat before running antifreeze through the cooling system. That's what we do here in the arctic.

If you keep the boat in the water, you'll have to rely on information from some of our more Southern brethren.

In any case, enjoy your wonderful CD.

--Joe

[Paul D.]

If it is a motor with antifreeze and heat exchanger, just run antifreeze through your sea water intake till it comes out the exhaust. Up here in the great frozen north we use -50 pink propylene glycol antifreeze. If it is a raw water cooled motor I would defer to others with experience successfully winterizing those. I also add fuel stabilizer to the diesel tank and spray a little fogging oil into the motor's air intake when shutting it down.

[steveg]

It gets pretty cold here. Well below freezing and freezing for months at a time. My procedure, not including water and waste, is as follows:

Add diesel fuel treatment and top up fuel tank.

Just before haul out motor around enough to get the engine hot. Change oil and filter.

Change transmission oil.

Run engine with the water intake in a gallon of antifreeze. Continue until the gallon is about gone. It should be coming out the exhaust, which I catch in a bucket. Shut down.

Remove drain plug on exhaust and open the drain on the engine. Put exhaust drain screw back and tighten engine drain in a couple of days after the fluid is finished draining.

Lift the compression level and rotate the engine with the hand crank while spraying about an ounce of fogging oil into the air intake.

Rotate the engine so the piston is top dead center. There is a post somewhere here where Maine Buzzard, I believe, gives excellent instructions how to do so.

Remove impeller, inspect and replace as necessary. I lube up the impeller with vaseline or light grease prior to reinstall.

Tape up exhaust and air intake with some blue painters tape which is easily removed in spring.

I may have missed something but that covers most of what I do.

[frankfurder]

Thanks for the responses, especially about the boat at lake Texhoma. My 25d is raw water cooled and stays in the water year round. I never thought about the lake Water acting as a heat sink thru the prop shaft.

I will continue to drain or add antifreeze and not worry about the thermostat open or closed.