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MAG 350 MPI SN1A317357 GAS Kuuma water heater install

UKMike

UKMike

Contributing Member
Hi all,

I’m hoping someone can help me understand the water flow and connection points on my MAG 350MPI, so I can connect my new Kuuma 6 gal external water heater. The engine has a sea pump with no exchanger, and looking at the below it suggests there is an elbow on the top of the front pump, is that right and if so, does anyone know where the other connection point is please? I can confirm, the front pump in the below link does have a blanking plug in the top for the elbow.


And the thermostat housing is the 3 pick up housing, with another blanking plug at the top, I assume that’s the other pick-up point?


Could anyone confirm?

Thanks in advance 😁
 

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The service manual I looked in suggests different spots....provide your serial number so I can get the correct manual and we can go from there...
 
for the return, the manual says use the plug on the side of the circulating pump (above the inlet casting) for the return from the heater.

for the supply to the heater, they give two choices: the first is on the intake manifold - remove the plug from the cooling passage (front of engine on the RH side) between the tstat housing mounting point and the flange...the other is to remove a lug on the RH side of the tstat housing.

The other caveat is to make sure the hoses to the heater are no larger than 5/8"ID .
 
Many thanks makomark, that’s amazing help, and I really appreciate it. The Kuuma also recommends 5/8 with a specific rating. Now all I have to do is work out what connectors to use, size and thread and work out where I can get them from and I’m sorted. Thank again top advisor!

Best
Mike
 
UKMike said:
Many thanks makomark, that’s amazing help, and I really appreciate it. The Kuuma also recommends 5/8 with a specific rating. Now all I have to do is work out what connectors to use, size and thread and work out where I can get them from and I’m sorted. Thank again top advisor!

Best
Mike
Click to expand...
For anyone else looking for the Mercury kit for this, the part number is 22-8M0119308.Thats the new number, it comes with 3 connectors, 2 at 5/8 and I believe one at 3/8. So covers the intake manifold connection, the circulation pump connection and the thermostat connection as advised above by makomark. Not sure about bottlenecking the feed down to 3/8 with a 5/8 return so will use the 5/8 for feed and return.

Thank again makomark, very helpful indeed.
Best
Mike
 
Good put on the part number...

keeping the hoses the same for feed and return is usually the best approach...

If you live in an area where winterizing the engine is a must do, don't forget to ensure the water heater gets addressed, especially with the raw water being used.
 
Will do and thanks, I’ve decided to add 2 merc drain points 861505A1 just below the Kuuma, inline of the feed and return pipes, then the internal Kuuma coil and pipes can be drained. Also going to add shutoff valves on both feed and return so that I can isolate the heater 🤓
 
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