coolant replacement

[Bruce]

I am preparing to change the fresh water coolant in a Yanmar 315 HP engine installed in a flush deck 28' Albin. The sea cock on the engine block under the oil filter is almost impossible to reach. What wrench type and size are necessary to reach this fitting and how best is it reached? Thanks for any information.

Bruce

[jcollins]

Any of you Yanmar guys have a suggestion for Bruce?

[Bruce]

John,

Thanks for raising the question as I had not received any replies. I did figure how to get a wrench to the petcock and was able to drain the coolant and refill with new coolant. For anyones information if they have the same problem, the hex head on the petcock is 10 mm.

Bruce

[furball]

Bruce, I'm getting ready to change coolant for the first time. By opening both the engine and heat exchanger petcocks, do you know approximately how much coolant you were able to drain? The manual indicates 10.5 liters in the system. Does this effectively drain most of the coolant? Seems like there would be quite a bit left in the system. For example, the coolant in the lines that run to the hot water heater. Is it necessary to fill the system with fresh water and drain again before adding the new coolant? Also, are there zincs on the freshwater side that need to be changed when the coolant is changed?
Thanks,
John

[RobS]

For example, the coolant in the lines that run to the hot water heater.

Yes, there will be coolant left over in this part of the system so it will need to be drained/flushed as well.

Also, are there zincs on the freshwater side that need to be changed when the coolant is changed?

No, the zincs are on the raw water side only.

[Bruce]

John,

By opening the two petcocks I believe that I drained all of the coolant in the freshwater cooling system. I did not drain the lines to the water heater but perhaps I should have. When I replaced coolant, I put in an amount slightly greater than the engine manuals stated capacity for the cooling system so I assume that almost all of it was drained. As Rob S. mentioned the zincs are on the saltwater side of the heat exchangers so they do not need to be replaced when replacing the freshwater coolant.

Bruce

[furball]

Changed coolant this weekend. Was trying to figure out how to catch the coolant as it drained without making a mess. I have a small Jabsco drill powered pump. The 1/4" suction tubing of the pump slips neatly into the 3/8" clear tubing already on the drain valves. Then I opened the draincocks and pumped the coolant into an old 5 gallon gas can sitting on deck. Took out slightly over 4 gallons.
John