I have a 1994 29.5. The engine is a 18hp Yanmar. The model number is 2gm20f. How do you change the enclosed fresh water fluid? There does not appear to be direct way.
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Instructions in the Yanmar Manual
Bob: There are instructions in the Yanmar Service Manual. I would suggest that you get one. Basically there are a couple of petcocks on your engine (starboard side). You open these to drain the fluid from the block. Remember that this is toxic and should be disposed of in a safe fashion.
Bob: There are instructions in the Yanmar Service Manual. I would suggest that you get one. Basically there are a couple of petcocks on your engine (starboard side). You open these to drain the fluid from the block. Remember that this is toxic and should be disposed of in a safe fashion.
29.5 Cooling System
The 29.5 runs the cooling fluid forward to a hot water heat exchange before returning to the reservoir. That's the lowest point, and is a relatively easy place to drain the system. If you drain it at the engine, you'll leave the old coolant at the water heater. There is a little valve in the hose leaving the top of the engine that you can turn to let air in as the fluid runs out. Remember, "fresh water" in this context means "coolant," so don't forget to add antifreeze when you refill it. Follow the coolant instructions so you get the proportions right (more is not better). Also, be sure to get the air out of the lines by running the engine with the "radiator" cap off to make sure all the bubbles are out and the system is refilled (as you would with a car) or you won't do much cooling. Check the archives for some excellent articles on this.
The 29.5 runs the cooling fluid forward to a hot water heat exchange before returning to the reservoir. That's the lowest point, and is a relatively easy place to drain the system. If you drain it at the engine, you'll leave the old coolant at the water heater. There is a little valve in the hose leaving the top of the engine that you can turn to let air in as the fluid runs out. Remember, "fresh water" in this context means "coolant," so don't forget to add antifreeze when you refill it. Follow the coolant instructions so you get the proportions right (more is not better). Also, be sure to get the air out of the lines by running the engine with the "radiator" cap off to make sure all the bubbles are out and the system is refilled (as you would with a car) or you won't do much cooling. Check the archives for some excellent articles on this.
Good point.
Gene: You make a good point about the water heater. My suggestion is to mix your antifreeze and water in a bucket in the proper mixture (depends on your geographical location). That way you will know exactly your mixture. The petcocks that are lower on the engine than the heat exchanger. I am wondering if you even need to use the petcocks if you are draining at the water heater?
Gene: You make a good point about the water heater. My suggestion is to mix your antifreeze and water in a bucket in the proper mixture (depends on your geographical location). That way you will know exactly your mixture. The petcocks that are lower on the engine than the heat exchanger. I am wondering if you even need to use the petcocks if you are draining at the water heater?
coolant change
Bob, get the manual, as suggested, but you must drain the engine petcocks and well as the hot water heater.Would be a good time to change to (if your not already using) the long term (5 year orange color) anti freeze. If you change to the long term I would suggest you do a flush (so as not to mix two types of anti freeze) and don't forget to change the overflow tank. Not has hard as it sounds.
Bob, get the manual, as suggested, but you must drain the engine petcocks and well as the hot water heater.Would be a good time to change to (if your not already using) the long term (5 year orange color) anti freeze. If you change to the long term I would suggest you do a flush (so as not to mix two types of anti freeze) and don't forget to change the overflow tank. Not has hard as it sounds.
Consider Long-Life Antifreeze
It's a lot of work changing the antifreeze all the time and it's bad for the system if it's not changed as required. Although it's a bit more expensive consider using long-life antifreeze to reduce your work. To add it, though, the system has to be essentially totally drained (the coolant is pre-mixed and water shouldn't be added) and all the old antifreeze flushed out.
It's a lot of work changing the antifreeze all the time and it's bad for the system if it's not changed as required. Although it's a bit more expensive consider using long-life antifreeze to reduce your work. To add it, though, the system has to be essentially totally drained (the coolant is pre-mixed and water shouldn't be added) and all the old antifreeze flushed out.
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