Hi, I've got a 1982 37c with a Yanmar 3QM30 which has been overheating. I've been systematically going through the systems and making good use of all previous posts on this subject. I have been replacing all cooling hoses as I go, and based on a recent Hunter Owner topic, I am going to tie in my previously unconnected coolant lines to the water heater. I know I want to tie in to the hot coolant (sorry) before the thermostat, and I believe two tees will be required to place the water heater in parallel with the heat exchanger. I seem to have a variant of the Yanmar 3QM series engines not described in any other posts. The heat exchanger is not a standard Yanmar model, but functionally appears the same. The engine has a raw water pump and a coolant pump, but unlike similar models the thermostat housing sits on top of the exhaust manifold and contained two thermosats facing in opposite directions. Also, the jacket around the exhaust manifold contains coolant, not raw water. The raw water exits the heat exchanger, goes through an inverted tee, and then enters the mixing elbow. I am not adverse to buying the manual, but I want to get the correct one- as well as the correct parts when ordering. I bought the Sealoc manual, which covers everything in general and nothing in detail, and I have downloaded portions of the 3QM30 manual, but nothing I've seen so far seems to match this particular engine. Any suggestions? Thanks for your thoughts.