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440 magnum runs hot idling

Mopar Muscle
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440 magnum runs hot idling

New User | Posts: 2 | Joined: 11/12
Posted: 11/12/12
01:29 PM

I recently built a 440 magnum. I increased the compresson some and installed a slightly stronger cam. The engine runs hot when it idles. I removed the thermose stat, have installed a larger radiator and a fan with more blades and the water pump seems to be circulating fine. I have adjusted the timing up and down to know avail. Could I have a head gasket or intake gasket on wrong? Any suggestions

waynep71222 waynep71222
User | Posts: 246 | Joined: 04/12
Posted: 11/13/12
07:11 AM

you did not say what kind of fan you are running...

let me delve into Thermodynamics of cooling systems..

and you are probably going to want to reinstall a NEW thermostat after you see how fast the coolant is flowing through the radiator at idle and at crusing rpms..

the Thermostat when installed blocks the flow of coolant into the radiator until the engine reaches operating temps..   the water pump circulates the coolant through the block and heads again and again through the bypass hose..  as it is blocked by the thermostat.. this circulation through the bypass also keeps the internal temps in the block and heads stable to eliminate hot spots.. like stirring a pan of water  on the stove..

the thermostat also allows the hot coolant after the thermostat cycles to come to a complete stop so the fan can take the heat out..

if you have a fan clutch.. you will need to run a 180 or 192F thermostat.. as the thermal fan clutch does not turn on till about 180... so if you have no thermostat or a 160.. the water will be circulating so fast through the radiator by the time the temp is high enough to turn on the fan clutch it will never be able to cool the engine...

if you have a flex fan.. or a rigid blade fan...    will the engine at fast idle hold a shop rag against the front of the radiator???

do you have a Fan shroud??? so the fan pulls an equal amount of air through the entire radiator.. not just the patch directly in front of the fan..

could the water pump impeller be worn down??? eaten away???

are you running an UNDER DRIVE pulley???  it may not spin the water pump fast enough to keep the coolant circulating at idle..

Why a new thermostat.. in the brass bulb is a lump of wax that expands when exposed to hot coolant..  when the engine is overheated. the wax expands farther and can escape the thermostat..  at that point there is not enough wax to  push the valve open on the thermostat and the engine will overheat....  

New User | Posts: 2 | Joined: 11/12
Posted: 11/14/12
09:22 AM

I do have a fan shroud. I took the original fan off and installed a rigid fan with more blades. I do not have a fan clutch. The pulleys appear to be original. But the water may be flowing to fast thru the radiator. I will install a new thermostat when I get a chance and see if that helps. Thanks for your help.