Fresh water flush Yanmar diesel

bgotbaum · #1 (**permalink**) 07-21-2003

Can anyone tell me how to fresh water flush my 1985 G3 27hp Yanmar diesel. It''s not circulating enough water to keep the engine from overheating.

I have cleared the raw water intakes on my saildrive, checked the pump hose to make sure its clear, pulled the water pump and inspected the impellar and looked for debris, and the water still trickles out.

The only other thing i can think of is buildup in the engine.

Any and all thoughts welcome.

Thank You, GG (Charleston, SC)

knothead · #2 (**permalink**) 07-21-2003

I''m a rigger, not a mechanic so I don''t claim to know what I''m talking about but a few years ago I installed a y-valve on my salt water intake just after the strainer and connected a hose which I ran into the bilge. I have a 10 hp salt water cooled Yanmar and what I did was partially fill the bilge with fresh water before I went out and then suck it back out with the engine when I got back to the dock. I figured it couldn''t hurt to have fresh water sitting in the engine between sailing trips rather than salt water. The bilge was kept clean that way too. Like I say, there may well be a valid reason why this is not a good idea or doesn’t help anyway, and I would be interested to hear others thoughts.

knothead · #3 (**permalink**) 07-21-2003

Actually, I wonder what would happen if I sucked some vinegar into the engine and let it sit for a few days.

ssmith8523 · #4 (**permalink**) 07-24-2003

I suspect your heat exchangers on perhaps both the fresh and raw water sides need to be de-scaled, especially if zincs have not been maintained. You can remove them and have them descaled in an acid bath. I had an overheating problem with my 25hp Westerbeke, and the mechanic pulled the hose off supplying water to the freshwater exchanger and blew air into it, and declared it almost plugged. He then grabbed a bottle of mild oxalic acid solution , held the hose straight up and poured the solution in, counted to 10, then flushed it out with water. Not something I would have the nerve to do myself! You may want to check your thermostat first to ensure it''s working properly.