Nissan Sentra Overheating issue

I own a 2002 Nissan sentra. I am having overheating issue. I’ve changed radiator, thermostat, water pump, water reservoir, even a/c belt. But the issue still persist. Any idea what could be the case?

Have you checked for a blown head gasket?



I am not sure but I’ve changed it a year ago.

Not all head gasket repairs are equal. It’s a pretty painstaking process. Short cuts can bring long troubles. Good luck and please let us know.

When the engine is cold, remove the radiator cap.

Start the engine, and as the engine idles watch the coolant in the radiator.

If bubbles begin to form in the coolant, that’s an indication of a blown head gasket.


Will have it checked again. The mechanic which repaired my cars state that when the temps went up, the water was not boiling. Is there a chance that the meter itself is faulty. But when the meter rises the fan does spin louder.

Thank you will have it check again probably from a different mechanic.

Forgot to mentioned that the temp rises and drop in a short time span. Roughly 5-30 seconds

We would need a lot more information. Does it lose coolant when it .“Overheats”? Is your radiator full when the engine is cold in the morning?

When your temp rises and fall in5 to 30 seconds, is your heater putting out full heat? If not that indicates low coolant level, either from a leak or a bad head gasket or from overheating and pushing the water out the overflow.

Does it overheat at idle, around town or on the highway?

Could be caused by an air pocket in the coolant. Have your shop elevate the front wheels, remove the radiator cap, then, adjust the heater to max hot, & start and idle the engine. Watch the dash gauge and the radiator as the coolant temperature rises. As the thermostat opens the top radiator hose will start to get hot, and the radiator cooling fan will turn on. Any big air bubbles burping up through the top of the radiator? If so, that means there were air bubbles trapped somewhere in the cooling system. Wait until all those air bubbles stop coming up, then turn off the engine and replace the radiator cap.

The shop should also measure the temperature of the coolant or the upper hose indepently (e.g. infrared device) to see if it is matching the dash gauge’s behavior. If not, once the engine cools down measure the resistance of the engine coolant temp sensor (the one used by the computer). What resistance does it measure at that coolant temperature?

That’s where I’d start w/this problem anyway.

It doesn’t seem to lose coolant but will have it check.

It is usually during idling, while driving the temperature stayed normal but usually after 30-1hour drive, once the car start idling that’s when the temp starts fluctuating.

Thanks will inform them to check.