My '95 200vrs MC standard 350 efi (indmar) which does not have the npt plug on the intake manifold for the input to the heater core. <BR> <BR>The heater core output will go on the water pump,lower right npt plug, or teed into the impeller input. <BR> <BR>There is a second plug on the water pump, on top. Is this intended for the heater core's input? <BR>

Well, I'm a bit hazy on this, but I believe on my 02' they removed a sensor or something on top near trhe thermostat and put in a "Tee" to hold the sensor and feed the heater. The return was near the front but not sure where. <BR> <BR>Hope it helps.

You probably need to take the heater supply line (hot water) from the engine block itself. Most people will take the hot supply line off one of the two main engine block drain plugs. If there wasn't hardware included in the shower, you will need to pick up a threaded barb to screw into the block and the slip the hose over. If you wanted to get even more creative, you could place a valve there too in case you ever needed to shut the heater flow off (for a leak, etc). You would also need a valve or check valve on the cold water return line to prevent water from flowing back into the heater from the "wrong" direction. <BR>

thanks airfreak <BR>that is what i was thinking would be best for heat but i'm hoping this is not going to bite me later if there is overheating. <BR> <BR>I wonder if the block drain/s, if I relocate the knocksensor, will run a big heater well.

Block drains will work but I wouldn't relocate the knock sensor. Maybe use the drain on the other side?? Does the indmar use dual knock sensors at each drain? I thought that the indmar sensors were just inside the hole on the drivers side (V-drive configuration) and you could still use the drain for heater/shower??

one knock sensor. <BR> <BR>would it be best to use a block drain over teeing the sensor located in the intake manifold? <BR> <BR>will 1/4 npt supply enough hot water for a 40,000btu heater?

1/4"npt seems small to me, i guess i was lucky my heater went in as you said up top, to the intake man. <BR>Try daves article here: <a href="http://www.wakeworld.com/articles/2002/heater.asp#Engine" target="_blank">http://www.wakeworld.com/articles/2002/heater.asp#Engine</a> <BR>The first fitting will go somewhere on the intake manifold toward the front of the engine or on the thermostat itself. Hopefully, you'll have a cooling system plug that can be removed to accommodate the 5/8" barbed fitting provided. If not, you may have to tee into the temperature-sending unit. Be sure to use Teflon tape on all your threads in order to prevent leaks. <BR>