Even engines have anodes
QWhile investigating the cooling system on my Volvo Penta engine, I came across a plug that the manual says contains the anode, but when I unscrewed the plug it looks like a blank hole. What’s it for? FK, via email
ATONY REPLIES: The plug is identical to the anode holder on my Bukh, in which a pencil style anode screws onto the smaller thread and then the whole lot screws into the engine. I suspect the plug unscrewed itself from the anode, which is still in the engine. I suggest screwing a bolt into the anode and applying a bit of force with a pair of grips. If you screw the bolt fully home you may twist the anode free.
The anode is to protect the internal engine parts from corrosion, because antifreeze cannot be used in raw water cooled engines. Changing the anode should be a yearly task until you assess its corrosion rate.