96 Nissan Sentra Overheating

When I stopped for gas while driving home from work last week I noticed steam coming from under the hood. On inspection I noticed that the external antifreeze reservoir was full, much higher than the max fill line and boiling. After letting the engine cool the reservoir level dropped. I checked and added antifreeze,50/50 mix, to the radiator. The next day I back flushed the heater core and radiator. It still overheats except when I drive with the heater running. The top radiator hose going from the engine to the radiator is hot after driving indicating the the thermostat is opening. Any suggestions.

Thank You,


The problem might be from a partially restricted radiator.

When you turn the heat on the heater core acts as a secondary radiator, where it removes heat from the coolant where a partially restricted radiator is no longer capable of doing.



Thank you for your reply. I noticed that after flushing the system there was still some antifreeze in the radiator. I had to disconnect the lower hose to drain the system since I didn’t see a valve on the bottom of the radiator. Do you think that another longer flush might clear the restriction?

Thanks Again,