Yanmar 4LHA-STP fittings for hot water tank hoses

[Brian Brown]

I’m not sure if this is the right forum to ask this question but I have seen many positive comments from Tony about theses engines so I decided to ask here. I was in search of a boat with 5.9 BT or 5.9BTA engines because of the known reliability and longevity. Unfortunately the boats that we liked powered with theses engines ended up having issues. (Not engine issues) We found a boat we liked with twin 4LHA-STP engines, 850 hours 80 % fresh water use but 20 years old so there are some maintenance projects in order. The one item not utilized is the engine closed cooling system used for heating a hot water tank and a Bus heater. I would like to install this. Is there a kit for this or specific fittings that are used for this and where are they installed. Thread type ?
NPT/
BSPP (BSP, parallel)
BSPT (BSP, tapered)
metric parallel.
metric tapered.

Sorry If this is not the forum to post Yanmar questions but I thought I’d give it a try!
Brian

Topic

[Tony Athens]

As I said it’s been years ( 10+) since I have dealt with these Yanmar’s.. IMO, assume NPT at this point. When in Yanmar school a long time ago, I was told the “A” used in the Yanmar model means it was made for us Yankee’s.. ..

[Brian Brown]

Thank you good information. I assume that these are not NPT? I’m going to be replacing the anti-freeze and flushing the cooling system. I will remove these fittings and install some type of barb fittings and ball valves.

[Tony Athens]

Yanmar 4LHA remote heater taps

Look at the picture. Not sure, but I’ll try and research is tap deeper.

[Author]

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