I don't agree with the previous answer.
First off, the radiator core is aluminum now and doesn't rust, second, it is normal for the bottom of the radiator to be cooler because that's how it works. The temp of the coolant lowers as it passes through the core to the bottom. Thirdly, that is not a symptom of a clogged radiator to act that way.
The temp is fluctuating because the sensor reads coolant and not air so if the sensor hits an air pocket, it reads cool, even if the engine is not.
Saturday, February 26th, 2011 AT 2:12 AM