3GM30F - water heater connection

[spinwing]

New to us, this year; 88 Hunter 35. Electric water heater (DC) works well but not so underway. I suspect that the boat has been repowered at some stage.
In the attached picture, you can see the end of two hoses - presumably inlet and return.
The catch is that there does not seem to be any way to connect the hoses to the engine - extensions obviously would be needed.
Does anyone have a picture of the engine water heater setup?

 

[Steve Dion]

I suggest that you get a manual for the 3GM engine. There should be a schematic for the plumbing. This appears to be the original engine (could be a replacement engine). That is what my friends 35 has too.

 

[kloudie1]

Water Heater Connection

David, it looks like the places on the engine where the connections go are plugged. The heater may have been changed but most likely, the heat exchanger coil inside the heater is leaking so the previous owner just plugged the tubes and “let her eat”.. I have attached a picture of my 3 GMF which I think has the same plumping scheme. In the picture of the top of the engine, the green stripe hose, center bottom, is one and the other is the black hose exiting right, just above the alternator .. Ya might want to pressure test your coil in the heater before going much further..

 

[Bob R.]

I concur with Claude, there appear to be brass plugs installed on the engine where the water hoses should be attached. I just replaced the water heater on a Hunter 356 with a Yanmar 3GM30F engine. The attached photo shows the heater hoses just behind the belt pulley for the circulating coolant water pump. The heater supply hose is just behind the return hose.

 

[spinwing]

Steve: I do have an original Yanmar Operation Manual and the plumbing diagram, such as it is, shows no outlet and return for the hot water.

Claude: Interestingly, your overflow tank is on the port side while mine is on the starboard side. Your pictures give me a good indication where to look. I will have to tap in some brass elbows.

Bob I take it form your picture and explanation that the return hose is the forward hose.
I wish that I had that much space, especially on the starboard side. I emptied the engine oil today and literally had to put the extraction hose into the dipstick opening by feel. L

 

[Jeff]

H33.5 1993 3gm30f

Here is a picture of our connections to the engine. Both the engine and the 110V heat the water quite well for us.

 

[seadaddler]

2007 3gm

Maybe you can zoom on my photo to help where to connect hoses for water heater.
You still have the water heater in the boat to connect the hoses yes.
Nick

 

[kloudie1]

SpinWing.. do pressure test the coil in the heater before hooking up the engine.. Your brass plugs are in the right places and I can't think of a reason to not have the heater hooked up unless the coil was leaking. .... unless the heater was replaced with one that does not have a coil in it and runs on 110v only. Happy Hunting!
Yes, The old 34's had the tank on the port side.. Dunno why they moved it for some later years models.. saves some hose, I guess..

 

[Steve Dion]

Nick:

I think you have a YM and not a GM engine.

 

[Bill Roosa]

Plug location

If you look at your thermostat housing you will see a square headed national pipe threaded plug. It looks like yours is brass. Take that out and go get an iron pipe street "L" (90 degree bend, male on one end and female on the other) and a 2" nipple of the same size. There are two types of iron pipe, black and galvanized. You want the galvanized. The black is for CNG and will rust mightily when used with water. Screw the "L" into the housing and then the nipple into the "L" This will give you something to attach the hose and two clamps to. Repeat same for the other plug which is near the alternator on the water pump housing (going from memory here but is probably brass also).

 

[seadaddler]

Yes

Steve you are correct it's the the newer YM but thought it would be close to the same as GM and would show some idea where the hoses are hooked up.
I am wondering why they were diconnected from the hot water heater maybe it leaked.
Nick

 

[Steve Dion]

I would guess that the heater leaked at sometime or they may have not wanted to winterize it.

If you are a day-sailor I could totally understand not wanting to mess with it.

 

[spinwing]

Thanks for the tip I will check the pressurization first.

 

[Claude L.-Auger]

Hi David,

Here is how I rigged mine after installing a rebuilt engine which came with plugs like yours. I made the unit with copper pipes to avoid rusting, using a 90 degrees elbow to then go straight up and another one for the lower hose. The T was installed to accept the sender for the temperature alarm. As the others have said, you will need to pressurized the water heater to make sure you have no leak. If that is too complicated, connect the hoses as they should be on the engine, then fill up with coolant, and removing the rad cap, test for pressure loss using a rad pressure tester. (you can rent one). You should get about 13 to 15 PSI. If you have a leak you will have a pressure loss. If not, you're good to go.

Good luck

 

[spinwing]

Plan

With your advice; here is my plan for the winter. Pressure test the system with rad tester; assuming that it is good, replace the hoses all the way back to the heater ~6', this will save a joint and one possible problem later, then connect to the manifold as indicated.

Thanks