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Discussion Starter #1
Looking for some advice. I installed a new Griffin radiator in my 66 GTO. I am still using the original fan. Running around town the temp is about 180. But if I get stuck in traffic the temp is jumping up to around 230.

Any ideas?

Thanks as always
 

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That is a classic symptom of a bad fan clutch.....at idle runs hot...that is when the clutch should run the fan, and not slip, either by Centrifigal fluid or temperature.....

Observe the fan at idle is it spinning strong? Or slipping? It should be spinning strong........watch your fingers around fans.....

Watch the fan when you shut the car off...have a helper turn it off.....does fan stop pretty quick?.....or spin and spin?

Free spinning at shutoff means it is not catching at idle ..it is supposed to slip at speed and catch at idle
 

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Why did you replace the existing one? Was it doing the same thing before you changed the radiator. Is it stock 389?
 

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Hot in traffic but normal going down the road is a classic sign of a fan problem: you are not pulling enough air through the radiator core to cool the engine. Fan shrouds are a big help, as well as the correct fan and fan clutch assembly. The fan blades should be half in, half out of the shroud when properly set up.
 
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