1. Obtain replacement “O ring” gaskets (2).
2. Drain coolant from heat exchanger (drain under aft end of heat exchanger.
3. Loosen / remove hoses that will interfere with heat exchanger removal.
4. Remove bolts securing alternator & alternator brackets. Secure alternator forward and out of the way (should not need to remove wires). Be careful not to lose spacer holding alternator to engine block.
5. Remove bolts from caps securing heat exchanger core. Tap caps with rubber mallet to loosen and remove.
6. Score end of heat exchanger core to align same with heat exchanger body. Slide forward and remove.
7. Clean / service heat exchanger core (Rod out tubes, soak in radiator flush for 24 hours. Clean with brass wire brush. Be careful not to lose straight horizontal rubber/plastic gasket mounted on aft end of heat exchange core. [Editor note: Yanmar recommends replacement of the O-Rings and end