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post #1 of (permalink) Old 05-27-2002, 07:19 AM Thread Starter
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CJ:Is the heater core always supposed to be Hot?

This may be a little elementary, but I don't remember. The new heater core in my Scrambler is really Hot. This is after the engine has reached operating temperature. The Temp gauge reads at less than halfway toward the Cold side. I have a 180 thermostat and new coolant. When I installed the new core there obviously wasn't any sort of valve, So I am sure coolant is cycling through it at around 180. Am I correct?

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post #2 of (permalink) Old 05-27-2002, 07:22 AM
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Re: CJ:Is the heater core always supposed to be Hot?

You are right, coolant flows through the heater core all the time. Some vehicles have a valve that controls the amount of flow through the heater core to regulate the interior temp, but CJ's use blend air doors in the heater box to regulate it.
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post #3 of (permalink) Old 05-27-2002, 09:10 AM
 
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Re: CJ:Is the heater core always supposed to be Hot?

What about putting in a bypass? I was thinking of doing it to my TJ. Using 2 Ts, short piece of hose, and 2 valves. This way I could shut the heat off during the summer. Will the core get damaged with no circulation though?
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post #4 of (permalink) Old 05-27-2002, 11:25 AM
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Re: CJ:Is the heater core always supposed to be Hot?

You shouldn't need the bypass and two valves. Just put a shutoff in the supply line. I've heard of the core getting plugged with sediment in old beaters, but a well-maintained vehicle shouldn't have that problem.
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post #5 of (permalink) Old 05-27-2002, 11:40 AM Thread Starter
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Re: CJ:Is the heater core always supposed to be Hot?

The supply would be the line from the top of the water pump. Correct??

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post #6 of (permalink) Old 05-27-2002, 12:01 PM
 
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Re: CJ:Is the heater core always supposed to be Hot?

My YJ (258) won't flow into the heater core unless the heater thingi in the cab is set to heat. not cold.

Found out the hard way while filling the coolant. I had to open the valve to get it full otherwise it was way low when I started the engine and used the heater.

But I also have a manifold heater/cooler.. so I dunno what the story behind my Jeep is.
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post #7 of (permalink) Old 05-27-2002, 12:37 PM
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Re: CJ:Is the heater core always supposed to be Hot?

Don't forget, coolant is also a lubricant AND contains rust inhibitors. You do the math... [img]images/icons/wink.gif[/img]
post #8 of (permalink) Old 05-27-2002, 03:02 PM
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Re: CJ:Is the heater core always supposed to be Hot?

The supply hose generally is between the pump and the thermostat in the system. On most engines it's just below the thermostat.

I doubt it really makes any difference anyway. In either hose it will stop the flow.
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post #9 of (permalink) Old 05-27-2002, 04:24 PM
 
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Re: CJ:Is the heater core always supposed to be Hot?

Yeah, the water is supposed to flow all the time. It uses a blend door to control temperature. If the blend door works right, there's no reason to shut off the water, but if you did stop it, you'd need a bypass, not just a shut off. Since you probably have a heated intake, a shut off would stop the flow to the intake manifold also.
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post #10 of (permalink) Old 05-27-2002, 04:44 PM
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Re: CJ:Is the heater core always supposed to be Hot?

Some older ford trucks had an "H" shaped coolant bypass valve that would do just what you are talking about, mid to late 70's I think.
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