It's easy
John, I presume that your Westerbeke is fresh-water cooled and not raw water cooled. That means that you have a heat exchanger with a raw water loop and a closed fresh-water loop on the engine. If your engine is raw-water cooled (no fresh-water loop) then the proceedure is somewhat different. For a freshwater loop cooling system, perform the following: Add a shock-level amount of biocide and a fuel-preservative to your diesel tank. Top off the diesel tank for the winter to minimize condensation. Close the engine raw-water seacock and remove the hose from it. Lengthen that hose (if necessary) using a plastic hose coupler and another length of the same size hose. Put that hose end in a 5 gallon bucket of water that is fed by a garden water hose. Drain and clean out the raw water strainer. Run the engine for 5-10 minutes (until warm) keeping the bucket filled with fresh water. This will flush out any salt deposits in your raw-water cooling loop including the raw-water strainer. Shut down the engine. Empty the bucket and refill with a 50/50 solution of engine-type polyproplyene glycol antifreeze. DO NOT use the 'pink stuff' for water systems, or the TOXIC ethylene glycol based antifreeze. I would mix about 4 gallons- 2 gallons of antifreeze and 2 gallons of water. With someone else to help you, have them watch the exhaust outlet for a color change of the antifreeze mix. Run the engine - briefly - until the antifreeze mix is observed to be flowing full-strength from the exhaust. Immediately shut down the engine. If 4 gallons of mix was not enough, mix more and repeat. ( I use 4 gallons for my 50hp Volvo and it is more than enough) If you have antifreeze mix left over, put it back in the jugs, MARK IT as 50/50 mix and save it for next year. Record how much mix you used for next year's reference. Reconnect the engine hose to the seacock. Do not open the seacock until the boat is hauled for the winter. If you are leaving the boat in wet storage, do not open the seacock until spring commissioning. Change the oil and filter while the engine is warm. Refill with the proper oil for your next season. Drain any water from your diesel fuel filter(s). Replace the cartridge fuel filters now or make a note to replace them in the spring. Inspect all rubber hoses and belts on your engine. Note if any need replacement and if so note the size, length or part numbers so you can get them over the winter. Add these tasks to you spring commissioning list. If you are replacing belts or hoses and you have spare items, use the spares first and then replenish the spare parts. Rubber parts like belts deteriorate with time and very old spares are likely to have a very short life just because they are old. Remove the raw-water pump impeller. I mark the outside edge of the impeller so I can replace it for the same rotation in case I reuse it the following year. Inspect the impeller. Replace if it has been used for 3 years or 300 hours REGARDLESS of how it looks. Replace if there are ANY signs of cracks or worn ridges/grooves on the blades. Leave the impeller out of the pump for the winter. Attach your engine key to the impeller so you won't forget to replace it in the spring. Clean the exterior of the engine with cloths to remove any water or oil/grease from the surface. There are protective sprays that you can apply to the engine exterior to protect it form rust/corrosion if you wish. Cover the air intake with a plastic bag to prevent moisture from entering the engine over the winter. Cover the entire engine with old towels. This will keep condensation from condensing on the engine and causing rust. Make of list of spring commissioning items and place it with your key. (ie., remove towels, plastic bag from air intake, replace belts/hoses, replace pump impeller, filters, etc.) You are done. Go home, begin planning for your next sailing summer, and pray for a short winter. Rich
