Heater problem after carb swap
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Freshman User
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Heater problem after carb swap
I just finished swapping the 2bbl for a 4bbl on my '81 F100 with 302 , my first significant engine modification - runs good . Now my heater doesn't work . Cleared the heater core and water flows through . Water pump and thermostat were replaced while doing the carb swap and it runs at proper temp . Replaced the pressure cap with a known good one . The heater hoses don't get warm . Here is what I think I may have done . To hook up the temp sender , vacuum control device and the heater hose , I chose to hook the heater hose on the thermostat cap , on the radiator side of the thermostat , because it seemed easier . Could that cause no flow through the heater core ? Thanks for ideas .
Elder User
Joined: Dec 2000
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From: Austin Texas (area)
Moderator
Joined: Nov 2007
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From: Denver Metro Area, CO
The coolant needs to flow from the engine block (and only the engine block) to
the heater core. Once that coolant heats up and the thermostat opens, the fluid
then also flows through the radiator (to cool it down).
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Freshman User
Joined: Mar 2009
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If I'm understanding you correctly, yes, this will cause your problem.
The coolant needs to flow from the engine block (and only the engine block) to
the heater core. Once that coolant heats up and the thermostat opens, the fluid
then also flows through the radiator (to cool it down).
Cargo Master
Joined: Apr 2003
Posts: 2,058
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From: Too close to Houston
It's not so much that you aren't connected to a hot water source. The water coming out of the thermostat is just as hot as the water coming out of the engine. The problem is that by attaching downstream of the thermostat you've connected both sides of the heater core to the same pressure water. You need the pressure drop across the thermostat to force water flow through the heater core.
I'll bet if you pinched the upper radiator hose a little the heater would warm up quickly. (Not that I recommend that as a long term solution.)
I'll bet if you pinched the upper radiator hose a little the heater would warm up quickly. (Not that I recommend that as a long term solution.)
