Re: Yanmar coolant light on
I am no mechanic... if it were my Yanmar 3jh2e I would verify the coolant was full via the pressure cap (when cool) and the reservoir tank had enough coolant. The opaque reservoir tank should be marked full and low. I would also verify the sending unit connections and ground were secure and clean. I would also check the sending unit unlikely it goes bad but may need a cleaning. If still having problems would consider flushing the system and installing yanmar recommended 50/50 coolant. IMHO use only Yanmar parts and products on your engine. I would also get, if you do not already have, the service and parts manual specific to your Yanmar. There are a lot of good sources online. I am a new customer to Merri Mar Yacht basin inc. in Newburyport MA for Yanmar parts. Torrenson Marine is another good source for parts and products.