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Yanmar Pleasure Boat Marine Engine Help
HOT WATER CYLINDER
The connections to most engines are similar to these shown below. In the odd case the outlet to the HW cylinder may be taken from the back end of the cylinder head. The threads are 3/8 inch PT, a metric pipe thread, most similar to 3/8 inch BSP (British Standard Pipe). Your Yanmar dealer should stock these with 1/2 inch, 13mm or 5/8 inch 16mm, hosetail (barb) connections for the hose. Dont accept butchery, running a NPT (USA) tap through the threads will weaken the thread and housing.
Any air trapped in the system will cause the engine to overheat.
Additional coolant will be required to fill the hoses and pipes inside the hot water cylinder. After the initial fill, and before going anywhere, run the engine at idle and slowly pour coolant into the heat exchanger tank until it wont take any more. Check again, before the sea trial, that the fresh water coolant system is full.
Warning: Do not remove the heat exchanger cap (radiator cap) while the engine is hot. YOU WILL GET BURNT!
JH series LH and LY series Cylinder Position
JH series engine connections
LH and LY series engine connections
INSTALLATION
