Overheating after driving for around 25-30kms

2005 NISSAN PULSAR
176,500 MILES • 1.8L • 4 CYL • 2WD • AUTOMATIC
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DHWANIL123
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The car is overheating after driving for around 25-30kms.
The radiator fan turns on and off when the A/C is on, but it still overheats, when the A/C is off, radiator fan does not work.
I have shown a mechanic, without a pressure test he said, he cannot see any visible leaks, and probably when the engine is middle hot, radiator fan should work, and it is not, so he asked me to change radiator fan.

Could you please help as I am confused if I should do it or not?
Jul 8, 2022 at 6:16 PM
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JACOBANDNICKOLAS
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Hi,

The fan could be bad, but based on his thoughts, I wouldn't just replace it. You could simply have a blown fuse or relay issue.

I have some questions. Does the engine overheat at highway speeds or only in stop-and-go traffic? How quickly does it overheat? Also, if you allow the vehicle to idle, the cooling fan shouldn't turn on until the engine reaches approximately 220 degrees F. If you are looking at your temperature gauge, that would be a little past halfway.

Has the thermostat been replaced, the radiator flushed, and is it losing engine coolant? Also, and don't laugh, does the heater work?

I know I asked a lot of questions, but to simply replace the fan motor may or may not take care of the issue. Additionally, there are fuses and relays that would need to be checked first before condemning the fan motor.

Let me know the answers to as many of the questions as you can.

Take care,

Joe
Jul 8, 2022 at 10:17 PM
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DHWANIL123
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As it starts to overheat, the temperature fluctuates while driving at any speed, or even when on signal. It goes up and down instantly.
No, thermostat has not been replaced nor has the radiator been flushed. I am losing the coolant faster. But the car was serviced in May.
Yes, the heater works, but it takes time for the heater to start, as in it takes time to turn cold to hot.
Jul 9, 2022 at 3:36 AM
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JACOBANDNICKOLAS
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Hi,

By chance, when the engine is cold, did you check the coolant level in the radiator? What you described sounds like low coolant or a faulty coolant temperature sensor.

Also, if you are losing coolant but the mechanic can't see a leak, either the engine is burning it in the combustion chamber, or it is leaking into the engine and mixing with the oil.

Do me a favor. Here are two links. Take a look at the first one and see if there is anything that mirrors your vehicle. If nothing does, then we need to pressure test the cooling system. You will need the pressure tester, but most parts stores will lend one to you.

https://www.2carpros.com/articles/head-gasket-blown-test

https://www.2carpros.com/articles/radiator-pressure-test

Let me know.

Joe

Jul 9, 2022 at 10:41 PM