I have a 78f250 with no factory air. I got a replacement heater core I'm installing. Does it matter which one heater hoses goes to each fitting on heater core? I was also wondering if I can put a ball type valve inline under hood to stop the flow of hot water into heater core,or does this line have to remain flowing at all times in order for motor to cool properly?

 

It doesn't matter.

 

I wouldn't bother with a valve to shut the flow off, it's not hurting anything flowing through the heater core....BUT if you did that, you'd need some type of bypass before the valve so the coolant could still flow through the system.

 

Water flowing though core in truck heats up inside of truck even with heater contols in the off position. In putting a ball valve inline will keep the extra heat out of the cab by keeping the hot water out of the cab. So your saying not to stop the flow of water though heater hoses ? I live in florida and the heater core is bypassed but I need heat sometimes for defrosting windows when it rains.

 

I'm saying that the flow of heat into the cab is minimal if you don't have the fan on and blowing across it, so why mess with the factory hose cofiguration.....

BUT if you do put a valve in, then yes, you need some form of bypass before it for the coolant to keep flowing when the valve is closed, or all you are doing is shutting the entire cooling system off because it won't be able to flow through the radiator to cool, it will be stopped at the valve, probably messing up quite a few things, and eventually overheating.

 

I'll hook it up to factory specs. I know that it will add some heat to cab when heater is off but will see how much. I didn't think that you can cut water flow off without overheating motor just double checking. The inside cab temps with heater core bypassed here in florida are bad enough(no factory a/c) without the aid of a hot water in heater core inside of cab with heater controls in the off position. Thanks

 

I need a manual heater control bypass valve. Any links? cheap solutions, control valve with built in bypass

 

Would any one have a pic(of wires) of where the blower motor plugs into at under dash? My blower motor has an orange & black seperate plugs on it but can't find the other plug that they plug into.

 

I am unaware of any problems arising from stopping coolant flow through the heater core, as all of the factory AC trucks had a inline valve that was vaccum operated to stop coolant flow, and to my knowlege there was no bypass installed from the factory, however most AC equipped trucks did have a larger radiator, so this might or might not contribute, but I am sure that the vaccum valve would stop circulation through the heater core. It might pay to do like a semi truck has and put a valve in that threads into the block so as to not have hose clamps everywhere, your choice.

 

Thanks for the reply on stopping water flow. I guess I'll plug hoses and find out .

I found the wire connection its under the hood .

 

The island is your heater core .. dam the feeder creek and it will never stop the river ..

 

So Redroad are you saying its allright to stop(not by pass) the flow to heater core without the motor overheating, I take it? or? I'm thick I don't know

 

Yep otherwise all the hydronic heating zones I put in for years with a zone control valve are wrong

 

I'm wanting to put a ball valve inline one hose to keep hot water out of heater core so it doesn't flow though heating the cab ever so slightly. Difficult to explain.

 

Yep a ball valve with barbed fitting ends will work just fine .. It should also be compatible with antifreeze if it's brass