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| That machine is a thermosiphone cooling system, purely convection circulation.
Generally, and contrary to what a lot of thermosiphone owners have been led to believe, the problem ain't the radiator, or antifreeze concentration.
Yanmars, be they thermo or water pump share a common characteristic of accumulating a load of sludge in the block itself. Over time, the sludge keeps the heat from transferring.
You'll find one or two pipe plugs on the lower sides of the engine, near the back. You have to remove them, and connect the block to a sourse of water.
Let the engine heat up to about 140° with the radiator cap off, and the supply hose connected. Once warmed up, put plenty of water flow in thru the connection, and flush the crap out.
When the water runs clear from the radiator neck, close off the supply, and let the engine warm up a second time. Repeat flushing process.
Generally 2 flushes will clean a Yanmar out.
Be aware, the pipe plugs in the engine are generally a bastard metric size, so you aren't going to find a fitting easily.
If you can't locate the rear block drains, you can probably flush via the temperature sender fitting. | |
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yanmar
