Coolant change...Volvo Penta 2003 diesel

[islandrunner70]

I have been the owner of a new to me boat for 1 year and have read that the coolant must be changed every 2 years. The engine has a fresh water cooling system. I am trying to figure out how to drain the old coolant. Any suggestions are greatly appreciated.

Thanks

[Irish rambler]

First test the specific gravity of your anti freeze to determine what frost protection you have, it may not be necessary to change the coolant at all. If you look around the engine you should see at least 2 small drain cocks on the block, to drain the anti freeze mixture these need to be opened until no more fluid runs out. I would recommend treating the cooling system with a radiator cleaner, then flush with fresh water before refilling with anti freeze mixture.
NEVER use plain water for the cooling system, anti freeze mixtures lubricate the water pump, prevent rust and keep liner seals in good condition.

[Pete7]

There is a drain plug towards the rear above the starter motor. However, if its seized solid then do it via the anode which is a square drive under the alternator on the same side. Have rags and a small bucket ready. Replace the anode if its more than say 1/2 worn away.

If you have a calorifier then that needs doing as well.

I think manuals are available from the Volvo Penta website as a download.

Pete

[Paul L]

It is pretty straight forward as noted above. The plug on the starboard side may need to come all the way out and then have a wire stuck into the hole to get the junk clear to make it flow. On my 2003 fresh water cooled I needed to clean out the coolant side with radiator cleaner every 3 or 4 years. Changing the coolant annually or every 2 years is a good idea on the older ones to help keep it clear and protected. These are supposed to be self-bleeding, but it can sometimes take some patience to get it bled. Fill, run a bit, refill etc. If you have a hot water tank that is teed off the engine, then sometimes you will need to bleed at the entrance to the tank, depending on how high it is.