Winterizing Costs.....

[Solitude]

Does this sound like a good idea?

I have a raw water cooled Yanmar 1gm10. I doesn't get cold enough to freeze here in Vancouver.
Last year I ran antifreeze through the motor by warming the engine up, shutting down, closing the seacock, and switching the inlet hose to freshwater, restarting the engine flushing and finally adding anti freeze until I could see it coming out the exhaust (yes I caught it in a bucket).

Given that it’s raw water cooled am I doing any good? (corrosion) She'll sit until Feb like this.

[Chief Engineer]

Just check the bottles....most that I see say they have anticorrosion properties.

also you might want to check your zinc while you are at it.

[Solitude]

Ya.
I understand that the antifreeze provides corrosion protection,,.. but I was wondering if its worth it... the motor is raw water cooled the other 9- 10 months of the year. Salt water coorodes metal quicker when the its warm which is why raw water cooled engins have a lower temp thermostat. So is it worth it to run glycol in for a couple months ?

[GordMay]

Originally Posted by Solitude

.... Salt water corrodes metal quicker when the its warm which is why raw water cooled engines have a lower temp thermostat...

The corrosion of metals in saltwater is a complex problem, with many factors involved including: temperature, salt concentration, oxygen concentration, fluid velocity and more.

The prime reason for running Raw-Water cooled diesels at lower temperatures (between 130 - 160 deg. F, usually 140F) than Fresh-Water cooled engines (between 160 - 190 deg. F, usually 185F) is that the precipitation of chlorides in seawater accelerates with elevated temperatures (± 130 - 165 def. F). When the salts fall out of solution (crystalize) at about 145 deg. F, they clog (scale) the engine galleries, typically at the hottest parts of the engine, which ultimately leads to poor water circulation, and overheating.

This not only accelerates corrosion, but also, in extreme cases, can actually block passages. For this reason, most raw-water-cooled diesels have a thermostat set at 145 F, at least 40 F cooler than a closed system. Running at this relatively lower temperature reduces an engine’s thermal efficiency, so a Raw-Water system simply is unable to produce as much usable power as its Closed Fresh-Water system counterparts.

Periodically, you need to disconnect the inlet and outlet hoses, remove the Thermostat Housing, and clean scale from the passages. The tube that connects the outlet hose to the exhaust elbow is another common point for salt buildup. A third place to check for crystallization is the Anti-Siphon Valve (if installed), which is sometimes installed in-line on the hose between the exhaust elbow and the thermostat housing. This valve prevents water from flowing back into the engine. If it gets clogged so that air can’t vent into the system, it’s useless.

[Solitude]

Thanks Gord

I'll check the build up when I commission her in the spring. I will be replacing the impeller and checking zinc/ thermostat/ changing oil etc..


Do you think its doing any good runing glycol into it for the couple months it sits during the winter here in Vancouver. There is very little risk of freezing. She's in the water. Or would it be better for the engine overall to go down every couple weeks and warm it up? (also a good excuse to hang out and relax)

Solitude

[GordMay]

My opinion is that a quality propylene glycol (50:50), with corrosion inhibitors, would be much preferable to water (salt or fresh).
I’m not a mechanic.
The very worst condition would be a dry (drained) cooling system, with the galleries exposed to air.

[Chief Engineer]

The main reason for non toxic antifreeze is to keep things from freezing.

Around these parts, there are usually a coupla boats that sink each year because of frozen lines bursting. This usually happens at night when it is colder. The thru hulls are left open and a strainer cracks....glub-glub.

Btw "Freeze plugs" (holes) are actually designed into castings to allow casting sand to be removed from internal passages....sometimes they work....sometimes not.