overheating radiator or air flow problem fred fellow corvette enthusiasts the problem is my ' roadster heats up during in town driving even on cool days however it cools down to the thermostat heating level degrees on the open road naturally i was thinking it was the radiator i recently removed it and had a radiator shop conduct a water flow test to my surprise it passed with flying colors when i explained the problem to the radiator repairman he said the overheating problem sounded more like an air flow issue due to it only happening during in town driving can anyone shed some light on this my car has a new clutch fan correct bladed fan and correct shroud however i have noticed the fan does not set all the way inside the shroud about half the fan blade's width is just outside the shroud could this make that much of a difference the radiator is an original harrison dated d but as far as i know the later model should not make a difference any help or advise on this matter would really be appreciated thanks for taking your time to help me in this matter
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Re: Overheating: Radiator or Air Flow Problem?
re overheating radiator or air flow problem carl rose hi fred i'll try to help you with this many factors influence an engine's running temperature cooling system capacity antifreeze mix resistance to flow in cooling circuit engine timing advance oil viscosity airflow through the radiator fan clutch and fan pitch shroud and seals radiator cap operating pressure radiator lower hose spring preventing suction collapse recent rebuild with tight tolerances i have heard it opined that the thermostat may restrict water flow even at operating temperature finally inaccurate ac temp guage senders fred i think you were on the correct track initially when the shop performed a flow test what did they measure i sincerely doubt that a y o radiator has no intrinsic scaling which would impair heat transfer capacity my car will run at on the freeway but heat up to with extended periods of idling i replaced my improper brass replacement with a dewitt aluminum reproduction which i have been highly satisfied with my fan with correct only semi functional clutch is about way recessed into the shroud i have seen folks use the a c radiator seals in the non a c cars to improve airflow although i do not know if this significantly improves radiator temperatures sorry have to go the er is calling carl -
Re: Overheating: Radiator or Air Flow Problem?
re overheating radiator or air flow problem john fred i agree with the diagnosis of your problem being airflow not cooling capacity if it cools ok on the highway and not around town the radiator is adequate from a heat rejection perspective i would suspect the fan clutch first these things are notoriously unreliable is it much harder to turn when hot than it is when cold if not it isn't working properly and that's why you're getting inadequate airflow through the radiator around town the fan blade position relative to the shroud is perfect shrouded fans are most effective when of the blade is forward of the rear edge of the shroud and are designed that way on purpose all this assumes of course that your thermostat is operating properly and your water pump impeller hasn't corroded to the point where it isn't generating sufficient coolant flow at idle rpm as another post indicated cooling issues can get very complex try the obvious first and go on from there johnComment
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