I am extremely sorry that I've just mixed the engine
models. Your lube oil cooler uses sea water to cool down the lubricating oil.
water system is of the indirect sea water cooled, fresh water circulation type. The cylinders, cylinder heads and exhaust
manifold are cooled with fresh water, and fresh water cooler (heat exchanger) use sea water.
Sea water pumped in from the sea by the sea water pump cools the lube oil in the lube oil cooler and then goes to the heat exchanger
, where it cools the fresh water. Then it is sent to the mixing elbow
and is discharged from the boat with the exhaust
gas. Fresh water is pumped by the fresh water pump from the fresh water tank
to the cylinder jacket to cool the cylinders, and the cylinder head
. The fresh water pump body also serves as a discharge passageway (line) at the cylinder head
outlet and is fitted with a thermostat.
does not make their own antifreeze as I know but advices brands and types depending on where you live. We are based in Fethiye/Gocek in Turkey and we use Castrol Antifreeze SF for the Yanmar engines. The antifreeze is pink and includes organic acids. It does not include silicate, phosphate, amine, borate or nitride. Its 3 liter package is sold for € 20,50 here. I don't know the 3 liter price far a good malt whiskey tough
The lube oil cooler material is brass (90/10 CuNi) except tubes. This is why Yanmar does not have any zinc anodes on the lube oil cooler.
I am a Materials Science Engineer
and would like to enlighten you about the material. Copper-nickel has excellent resistance to uniform corrosion
, remarkable resistance to localised corrosion
in chlorinated seawater and higher erosion resistance than other copper alloys and steel
. It is also resistant to biofouling. The cause of the failure is mostly attributed to the composition and production of the alloy, occurance of erosion-corrosion and corrosion damage in polluted waters.
In your case I'd suspect from the components of the cooler (manufacturing) and polluted seawater which is very common in harbours. There is very little to do to prevent this happening again if any.
Below you can find the Yanmar Service
Manual advice on inspection
of the cooler:
To inspect the oil cooler:
* Clean the inside of the sea water pipes with a wire brush to prevent the build up of saale
* If the rubber hose connection or welds are corroded, repair or replace the cooler.
* Apply the following water pressures to the sea water and lube oil lines to check for any leakage. Repair or replace the cooler if there are any leaks
Lubricating oil circuit: 1,5 kg/cm2 (test pressure)
Sea water circuit: 4 kg/cm2 (test pressure)
Hope I helped