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#1 Yanmar Diesel Engine Repair San Diego

How To Get Your Yanmar Engine Ready For Winter

You’ve taken proper care of your diesel engine throughout the season – that’s commendable. But, don’t relax just yet. Winter is ahead and your engine needs to be well taken care of in order for it to perform as smoothly as it did in season. Here are guidelines on how to winterize your Yanmar or any other marine diesel engine.


Yanmar diesel engine 

Diesel fuel is susceptible to growing stale and harboring bacteria in storage. This especially holds true of the newer kinds, such     as bio-diesel and low-sulfur kind. What happens is sludge and sediment build and these can clog filters, cause starting problems   and generally damage the engine.

If you leave the tank empty, that’s an ideal environment for condensation which will eventually collect water at the bottom of     the tank. You probably know this is a big no-no for diesel engines.

To prevent these problems, the tank should be topped up before storage. To make sure no bacteria develop, treat the fuel with   some diesel biocide that stabilizes the fuel. It would be good to have primary and secondary filters installed and then bled to get rid of air.


The acids in old diesel oil can eat away at metal components during winter storage. That’s why you should drain or pump the old oil, change the oil filter and tank up the crankcase with fresh oil as specified by manufacturer. You should also have oil for transmissions changed.


Opening drain plugs will purge the raw-water cooling systems. Your manual will tell you where the plugs are located. Using a stiff wire will enable you to clean the built-up deposits sitting in the drains. You will clear water from the pumps if you bump the ignition, but don’t start the engine. If your boat spends the winter afloat, you will clean the system if you close the seacocks that let raw-water in and then remove inlet hoses, pump covers and drain plugs. Next, replace the drain plugs, lightly coat intake-pump impellers with Vaseline and put new covers. 

Preventing freezing-up

You will want to ensure your engine is corrosion-proof during free. To do that, plumb the motor flushers or intake pumps to take some antifreeze from a bucket or a tank and then run the engines one after another so that the solution exits through the exhaust. This will remove standing water and coat the insides with anti-corrosion liquid. It’ll also coat everything with the fresh oil you put previously.

Ahead of spring

You can check your engine’s zincs, belts, electrical connections and O-rings. Have a look at the transom and the exhaust outlets as they get a lot of water. If anything looks fishy it’s better to repair it, replace it or service it before next season. 

Seal things up

Use some plastic and duct tape to seal off the outlets on the hull together with the engine’s air filters. That way you’ll keep your combustion chambers safe from moisture that could seep in through open exhaust or intake valves.

If your Yanmar engine or any other brand marine diesel engine needs repair and servicing, Propulsion Controls Engineering in San Diego is here for you. We are a company well-established in the market and our experience and commitment to premium workmanship allow us to deliver you the best solutions and repair for your Yanmar diesel engines.  
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