Does coolant flow thru heater always? - Page 2 - Chevelle Tech
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post #16 of 20 (permalink) Old Jan 11th, 20, 5:24 PM
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Re: Does coolant flow thru heater always?

Originally Posted by paul bell View Post
hahaha yessir, 10% coolant, 90% water.

Darn "edit" expires so quick...................

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post #17 of 20 (permalink) Old Jan 12th, 20, 12:58 AM
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Re: Does coolant flow thru heater always?

Having also driven my 1970 in Hawaii for many years, I can say having the heater connected will not help with cooling the engine. It is correct on the A/C equipped cars, one heater hose had a vacuum-controlled shutoff valve that would stop coolant flow to the heater core unless the control slider was moved to provide heat. During warm periods, no coolant would move through the heater.
At what water temp will the electric fans turn on? Are the fans the puller type between the radiator and engine? How many CFM provided by the fans? Too little airflow through the radiator will cause overheating.
Retarded ignition timing and the use of ported, not manifold, vacuum to the ignition advance unit can produce extra heat.
Long tube headers radiate a lot of heat in the engine compartment. Perhaps consider coated headers or a header wrap to reduce underhood temps.

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post #18 of 20 (permalink) Old Jan 12th, 20, 7:27 AM
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Re: Does coolant flow thru heater always?

Originally Posted by chevyhawaii View Post
Still dealing with over-heating issues with my 70 Chevelle. Won't go thru in detail the list of things we have done to try and fix this but after new upgraded aluminum radiator, new electric fans and bigger alternator, upgraded water pump, flushing, re-flushing, new tsat, new gauges, timing changes, new belts, hoses, etc. it is still overheating. One thing we did do when putting in new radiator was to disconnect heater hoses (don't need a heater here in Hawaii). My question here is, do you think reconnecting heater would help with cooling problems? Thinking that the heater core acts like another small radiator, but does the coolant flow thru the heater core if the heater isn't turned on? Do you think it's worth it to reconnect heater and would I need to have heater running to make that difference?

Thanks, Ben.

Dive into some of the other probable issues. What heads are on the motor, what head gasket did you use? How much timing are you running at idle and cruise? How is the carb tuned?

As for cooling system, nothing beats an OEM 7 blade fan, Hayden HD Thermal clutch and factory shroud. Ran this setup on my 540" with a dual core (two 1-1/4" core) alum radiator, factory AC condenser and trans cooler, all stacked up one in front of the other, overheating was a non issue.

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post #19 of 20 (permalink) Old Jan 12th, 20, 7:43 PM
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Re: Does coolant flow thru heater always?

Had a '65 Pontiac started running hot/overheat on highway. After chasing many of the "usual suspects" it turned out to be the vacuum canister on distributor had stopped working; replaced it and temps came right back to normal...a $10 part AFTER swapping numerous higher dollar parts.

Let us know if you find problem.

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post #20 of 20 (permalink) Old Jan 12th, 20, 8:02 PM
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Re: Does coolant flow thru heater always?

what is hot is it boiling water out the radiator cap overflow or just the gauge temperature put a recovery tank on it and then it will not run out on the ground and go back in the rad. when it cools down just my thought
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