colored water when draining the block for winterizing - the block is cooled by fresh water intake from Lake Whitney, on the Brazos river just northwest of Waco TX. Do any other Yanmar owners see this same thing? It is pretty consistent. This YSM8 is a 28 year old 8 hp single cylinder diesel. On a 28 foot sailboat it is almost comical - it knocks and rattles something awful, slowly but reliably moves the vessel, unless wind is too strong. If the oil is not too cold I can start it using the compression release and hand crank. The positive side is that it consumes only a tablespoon of fuel or two to motor out of the harbor. Thanks in advance for any insight on the coolant question, Drake.
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Ferrous Oxide ....
Ferrous Oxide is BLACK or BLUE/BLACK form of rust .... and ferrous oxide is a PROTECTIVE form of rust in a cast iron engine. That black water contains ferrous oxide and is coming from a 'dead leg' of the cooling system. Ferric Oxide is RED or RED/BROWN rust is destructive in a cast iron engine. If you want this engine to last, fill it with antifreeze that contains a rust inhibitor .... and store this engine WET for the winter to keep the ferrous/black internal coatings intact. If you allow the engine to 'dry-out' that black coating will turn to a red/brown coating (the 'destructive form' of 'rust') and the 'life' of the engine will be diminished. Never store a 'marine' engine 'dry' for the winter; always keep the internals of the cooling passages wet (and with a rust inhibitor). Marine engines dont wear out, they corrode away from the inside - out.
Ferrous Oxide is BLACK or BLUE/BLACK form of rust .... and ferrous oxide is a PROTECTIVE form of rust in a cast iron engine. That black water contains ferrous oxide and is coming from a 'dead leg' of the cooling system. Ferric Oxide is RED or RED/BROWN rust is destructive in a cast iron engine. If you want this engine to last, fill it with antifreeze that contains a rust inhibitor .... and store this engine WET for the winter to keep the ferrous/black internal coatings intact. If you allow the engine to 'dry-out' that black coating will turn to a red/brown coating (the 'destructive form' of 'rust') and the 'life' of the engine will be diminished. Never store a 'marine' engine 'dry' for the winter; always keep the internals of the cooling passages wet (and with a rust inhibitor). Marine engines dont wear out, they corrode away from the inside - out.
Good Advise
Drake - Rich was right-on with this advise. Make sure you fill the block with a rust-inhibiting anti-freeze. It's easy to do - just remove the intake line and put it in a bucket of anti-freeze and run the engine until its all sucked in and comes out the back. Make sure you first get the engine all warmed up so the termostate is open. I have a '78 Catalina 30 with a YSM12 - slightly bigger but so is my boat. It is a joke but it does get her up to hull speed. I had the engine rebuilt for 1/3 of the cost of repowering and it runs great. I bought the boat with the engine needing a rebuild so it was well worth the investment. I can't believe how little fuel they use. I could seriously be fine with a portabe 6-gallon tank for an entire season! Rob
Drake - Rich was right-on with this advise. Make sure you fill the block with a rust-inhibiting anti-freeze. It's easy to do - just remove the intake line and put it in a bucket of anti-freeze and run the engine until its all sucked in and comes out the back. Make sure you first get the engine all warmed up so the termostate is open. I have a '78 Catalina 30 with a YSM12 - slightly bigger but so is my boat. It is a joke but it does get her up to hull speed. I had the engine rebuilt for 1/3 of the cost of repowering and it runs great. I bought the boat with the engine needing a rebuild so it was well worth the investment. I can't believe how little fuel they use. I could seriously be fine with a portabe 6-gallon tank for an entire season! Rob
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