Winterizing the raw-water side
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Oil change, fuel, testing the coolant, and pushing non-toxic antifreeze through the raw-water circuit until it comes out pink — generator and A/C too.
Sources (5)
- Change oil and filter before lay-up (acids and moisture pit bearings), change fuel filters; diesel tanks left full to minimize condensation and algae; freshwater side coolant checked with a hydrometer at room temperature; raw-water side filled with non-toxic propylene glycol; close the seacock, run at idle until antifreeze discharges from the exhaust for thirty seconds or more; funnels that fit inside the sea strainer; have extra antifreeze handy; generator and air-conditioning raw-water circuits too — boatus.com
- Mistakes in draining or antifreezing the engine cause most BoatUS freeze claims; expanding ice cracks blocks and manifolds; ethylene glycol is highly toxic; attach a tag as a reminder of lay-up steps that affect the next start — boatus.com
- Propylene glycol winterizing antifreeze is commonly dyed pink for identification — westmarine.com
- Cutting off the water, even for a few seconds, can heat-damage and ruin a rubber impeller — impelpro.com
- Yanmar: if there is a risk of freezing, check that the cooling system contains enough coolant; seawater left in the engine may freeze and damage the cooling system — yanmar.com
General guidance for recreational boaters — your engine and equipment manuals and local regulations come first.