Engine overheating

Tiny
BLESSING EWOBOR
  • MEMBER
  • 2004 TOYOTA 4RUNNER
  • 6 CYL
  • AUTOMATIC
  • 169,675 MILES
Hello, the vehicle's engine is overheating. I have checked the coolant level of the radiator, it is okay and the fan is not using power. What could be the cause?
Sunday, December 6th, 2020 AT 6:49 PM

5 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

Do you mean the cooling fan isn't working? Does the vehicle overheat when you are driving at highway speeds or is it only when in stop and go traffic?

The most common cause of overheating is a stuck thermostat. Take a look through this link. It explains how one works.

https://www.2carpros.com/articles/how-an-engine-thermostat-works

To be honest, this is the first place I would start, replacing the thermostat. However, I would like to know the answers to the questions I asked above.

If, however, you want to just replace it, here is a link that shows in general how it is done:

https://www.2carpros.com/articles/replace-thermostat

Here are directions specific to your vehicle. The attached pic correlates with the directions.

________________________________

Hint: if the thermostat was not installed, cooling efficiency would be harmed. If the engine should tend to overheat, do not remove the thermostat.

1. Drain engine coolant
2. Remove v-bank cover
3. Disconnect radiator outlet, no.2 hose clamp or clip

Pic 1

4. Remove water inlet w/thermostat
a. Remove the 3 nuts, water inlet with thermostat and gasket.
5. Install water inlet with thermostat
a. Install a new gasket to the water inlet with thermostat.
b. Install the water inlet w/ thermostat with the 3 nuts.
torque: 9.0 nm (92 kgf-cm, 80 inch lbs.)
6. Connect radiator outlet, no.2 hose clamp or clip
7. Add engine coolant
8. Check for engine coolant leaks
9. Install v-bank cover

a. Install the V-bank cover with the 2 nuts.
Torque: 7.5 Nm (76 kgf-cm, 66 inch lbs.)

_______________________________

Let me know if this helps or if you have other questions.

Take care,
Joe
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Sunday, December 6th, 2020 AT 9:18 PM
Tiny
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It seems that the cooling fan is working because it is attached to one of the engine pulley directly and not using electrical components. The vehicle overheat on highway speeds.
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Monday, December 7th, 2020 AT 3:43 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 109,885 POSTS
Hi,

Okay, then the first thing I would recommend is replacing the thermostat. I asked that question because at highway speeds, the airflow doesn't require the fan to do anything. Since it overheats when moving, I would replace the thermostat. The is the cheapest thing to try and the most likely problem.

Let me know if I can help or if you have other questions.

Take care,
Joe
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Monday, December 7th, 2020 AT 6:47 PM
Tiny
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  • 687 POSTS
Thank you.
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Thursday, December 10th, 2020 AT 4:41 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
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You are very welcome. Let me know if you have other questions or need help.

Take care,
Joe
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Thursday, December 10th, 2020 AT 8:54 PM

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