Yanmar 1GM10 cooling system, needs a good cleaning.

[SVDistantStar]

Ok, so the little Yanmar in Lola has been setting idle for 3 years. In my other thread for the fuel filters someone brought up the cooling system. The boat came with a bunch of spares and i did change the impeller. After changing the impeller it still wouldn't pump water out the back. I went back into it and checked the water hoses that i could remove and found them to be full of some white crud. I cleared this out and it pumps water just fine now. It doesn't over heat or have any issue, but i would like to clean the cooling system out.

What can i run through the system to clean it? The motor is raw water cooled and is in salt water. For the most part ive got real good access to the front of the motor and almost no access to the rear of the motor. I plan on installing an access hatch in the cockpit floor right above the motor.

Now what other things should i be looking at. The oil is ok since the last owner wrote on the filter when it was changed, 600hours is when it was changed and it had 611 when i got the boat, 617 now.

[JimsCAL]

Circulating oxalic acid though the engine cooling passages will get rid of the scale that forms when using raw salt water for cooling. You can get it in most hardware stores as a box of crystals.

You should change the oil at least annually, regardless of engine hours.

[SVDistantStar]

The oil is on the list of things to be done, but its not that high up yet. Fuel and cooling are top right now.

Im guessing i just mix up a bucket of the crystals and water and let the motor suck it in?

[JimsCAL]

I found a nice detailed procedure of how to do this for an Atomic 4 on the Internet some time ago. A Google search should find it. Basically dissolve the crystals in a bucket with water and circulate with a portable pump. Don't forget to remove the thermostat or it may be damaged (mine was once when I did this to my engine). When done flush with fresh water and baking soda to neutralize the acid. Does a great job.

[tonic]

The thermostat opens at 110 degrees when you pull it to flush the engine check to see that it's working properly. If it has some years on it better yet replace it, you'll have to take the fuel line off to do it and bleed the engine when tou done. Make sure to scrape of the old gasket and put a new one on. Also being in salt water change your zinc yearly and again remove and replace the gasket. The thermostat and zinc use the same gaskets which is nice. Muriatic Acid I've know people to use I never have. Seems to toxic to me. Respirator and gloves, good ventilation a must.