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Discussion Starter #1
My Cummins Shop Manual shows the Hot Water hook up for the cab heater to be;

Heater feed, 3/4" NPTF Heater connection on left side, rear of head and the Return connection to be a 1/2" NPTF port on the lower water inlet elbow. I have used this hookup on another conversion and had reasonably good heat.

However, I have heard of some guys hooking the feed from the port on the Thermostat housing and returning it to the lower water inlet elbow port. Has anyone tried your heater with this connection ? It gets Bloody Cold where I live and I want the best possible hot water flow for my heater.

Thanks
Paul
 

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The best heat would be one in the head and one in the lower neck,this is how the 94-98.5 6bta are ran from the factory.

The rear port on the head on a 6bta is where they put the temp sender.

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Scott
 

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The best heat would be one in the head and one in the lower neck,this is how the 94-98.5 6bta are ran from the factory.

The rear port on the head on a 6bta is where they put the temp sender.

Thanks
Scott
I agree. The heater water flow should bypass the thermostat. One hose should be connected to the front top side of the cylinder head and the other end should always go to the suction side of the water pump. This permits coolant flow through the heater before the thermostat opens completely. Either hose should have a shut off valve for Summer use.
 

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Discussion Starter #6
Thanks for your replies. I am curious why Cummins specs the ports listed in my first post for the heater, and you have found other ports to work better. As I mentioned, I plumbed my Carryall per the Cummins Spec. The heat is decent, but I am about to plumb my M37 and want the best heat possible. I am just trying to understand the differences in ports usage. Thnaks for your patience

Paul
 

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I think the warmest coolant would be found at the highest point in the water jacket in the cylinder head near the thermostat. The engines in an automotive applications are usually tilted slightly from front to rear. In an industrial application, such as a crane or forklift, the engines are mounted a bit more level.
Maybe it is a hook up specification for industrial type engine? The most important part is getting all the air out of the cooling system and everything should work just fine.

Bob
 

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Discussion Starter #9
I agree and the replies make sense. I also just checked the other 4BTA's I bought last fall. All are plumbed, water out of the top, front of the head and returned to the lower elbow port. The Temp sender is in the rear left (driver) side of the head. Exactly the way you describe. Soooo, I will do the M37 this way.
Thanks for your replies

Paul
 
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