When in motion , the temperature guage goes above middle but in traffic it comes back to normal.
Car newly acquired
The fans working directly
Water level in radiator not reduced
I noticed a sign of radiator sealant at the edge of radiator opening.
Thermostat still there
Toyota brand

Please what could be wrong and what should I do?

The two fans don't suppose to work directly.

You can remove the thermostat .
Where do you stay.
If you stay in Lagos precisely (ojota,ketu) or nearby I can recommend my rewire for you.
I remove the thermostat of my 1st car but the 2nd one I have not remove it since 2yrs now because is working fine

aaking:
The two fans don't suppose to work directly.

You can remove the thermostat
Where do you stay.
If you stay in Lagos precisely (ojota,ketu) or nearby I can recommend my rewire for you.
I remove the thermostat of my 1st car but the 2nd one I have not remove it since 2yrs now because is working fine

Whatever you do, do not heed the advice to remove your thermostat @op

adesanyadotun:
When in motion , the temperature guage goes above middle but in traffic it comes back to normal.
Car newly acquired
The fans working directly
Water level in radiator not reduced
I noticed a sign of radiator sealant at the edge of radiator opening.
Thermostat still there
Toyota brand

Please what could be wrong and what should I do?

i think a picture would do much talking

Normally if the car as its thermostat and relay controlled fan, if in traffic and coolant temperature rises, the thermostat will open to let in cool coolant from the radiator into the engine, then your fan kicks in to help the hot coolant coming from the engine to cool down. "Dont be fooled by those who say this system is for Western World due to cold climate" this statement is from Kazeem mechanics who dont understand optimum operating aka best temperature to get maximum effiecent from an engine without damaging it, running an engine at cold aka anything under 70 degrees is uneffiecent and also damages the engine in the long run


Your car is doing usually opposite, most cars overheat in traffic due the the fact that there is no air flow the radiator due the car being stationary

Since yours overheats during driving it might be a headgasket gone, why becoz there is more heat generated during driving aka at high RPM than in traffic were your RPM are low

Just let a good mechanic check all possibilies that might cause overheating

adesanyadotun:
When in motion , the temperature guage goes above middle but in traffic it comes back to normal.
Car newly acquired
The fans working directly
Water level in radiator not reduced
I noticed a sign of radiator sealant at the edge of radiator opening.
Thermostat still there
Toyota brand

Please what could be wrong and what should I do?

Check and make sure none of your brakes are binding.
If none, replace thermostat. Do not remove but replace.

aaking:
The two fans don't suppose to work directly.

You can remove the thermostat .
Where do you stay.
If you stay in Lagos precisely (ojota,ketu) or nearby I can recommend my rewire for you.
I remove the thermostat of my 1st car but the 2nd one I have not remove it since 2yrs now because is working fine

You should not remove the thermostat!!!
Investigate and troubleshoot the cooling system.

It's very difficult to educate a Nigerian. Our educational system has failed!

You may have a partially stuck open/closed thermostat.
Remove the thermostat. If the issue becomes solved, get a good thermostat and put there.

Dont stress yourself with thermostat this, thermostat that.
If your thermostat has a problem, and is stuck closed, you will have over heating whether stationary or at speed.

I am fairly confident that your radiator is the problem.
At low load (low rev in traffic) the radiator works fine.
At higher load (higher rev on the move) radiator unable to keep up with the heat dissipation needed.

Firstly, check to confirm that your fan is blowing in the right direction.
It could just be blowing outwards and this counters/cancels the air rushing in while you are driving, thereby making the heat dissipation of the radiator insufficient. things will work fine when you are in traffic since the air from outside is low as you are on low speed.

Secondly, if fan is blowing correctly, proceed to wash your radiator inside out. make sure the fins are free of debris and it is not heavily rusted inside.
Replace with recommended coolant.

Lastly, you might want to check to make sure your radiator was not "changed" at some point during life of the car. maybe an underrated unit was installed.

As long as radiator is clean, coolant level is good and not losing fluid, water pump works fine, fans are blowing (in the right direction), thermostat not stuck closed, A car should not over heat.

ps: I'm not an expert, just using small common sense.

Kudos. Very valid points.
Next time, just go ahead to contribute without criticizing others.

Areaboy2:
Dont stress yourself with thermostat this, thermostat that.
If your thermostat has a problem, and is stuck closed, you will have over heating whether stationary or at speed.

I am fairly confident that your radiator is the problem.
At low load (low rev in traffic) the radiator works fine.
At higher load (higher rev on the move) radiator unable to keep up with the heat dissipation needed.

Firstly, check to confirm that your fan is blowing in the right direction.
It could just be blowing outwards and this counters/cancels the air rushing in while you are driving, thereby making the heat dissipation of the radiator insufficient. things will work fine when you are in traffic since the air from outside is low as you are on low speed.

Secondly, if fan is blowing correctly, proceed to wash your radiator inside out. make sure the fins are free of debris and it is not heavily rusted inside.
Replace with recommended coolant.

Lastly, you might want to check to make sure your radiator was not "changed" at some point during life of the car. maybe an underrated unit was installed.

As long as radiator is clean, coolant level is good and not losing fluid, water pump works fine, fans are blowing (in the right direction), thermostat not stuck closed, A car should not over heat.

ps: I'm not an expert, just using small common sense.

EngRichie:
Kudos. Very valid points.
Next time, just go ahead to contribute without criticizing others.

thank you.
i Didnt mean it to come across as criticism.
My apologies

I almost destroyed my Auto transmission and Engine because of this. Very dangerous problem to develop on the high way.

9icetoo:

Check and make sure none of your brakes are binding.
If none, replace thermostat. Do not remove but replace.

Just change ur radiator or coolant cover I have same experience.

Also if the radiator is single cell, this will hapun while travelling a long distance . Change it to double cell

Just change ur radiator/coolant cover I have same experience.

Also if the radiator is single cell, this will hapun while travelling a long distance . Change it to double cell

Don't forget, is the coolant going round your engine fast enough, you might want to check your water pump too.

Billiebaba:
Don't forget, is the coolant going round your engine fast enough, you might want to check your water pump too.

This is the best answer.

kingreign:


This is the best answer.

But boss what if the coolant doesn't show sign of damage tru leaks in weep hole?

Areaboy2:
Dont stress yourself with thermostat this, thermostat that.
If your thermostat has a problem, and is stuck closed, you will have over heating whether stationary or at speed.

I am fairly confident that your radiator is the problem.
At low load (low rev in traffic) the radiator works fine.
At higher load (higher rev on the move) radiator unable to keep up with the heat dissipation needed.

Firstly, check to confirm that your fan is blowing in the right direction.
It could just be blowing outwards and this counters/cancels the air rushing in while you are driving, thereby making the heat dissipation of the radiator insufficient. things will work fine when you are in traffic since the air from outside is low as you are on low speed.

Secondly, if fan is blowing correctly, proceed to wash your radiator inside out. make sure the fins are free of debris and it is not heavily rusted inside.
Replace with recommended coolant.

Lastly, you might want to check to make sure your radiator was not "changed" at some point during life of the car. maybe an underrated unit was installed.

As long as radiator is clean, coolant level is good and not losing fluid, water pump works fine, fans are blowing (in the right direction), thermostat not stuck closed, A car should not over heat.

ps: I'm not an expert, just using small common sense.

At the bolded, not so true.
I've had a thermostat stuck closed on my skoda. Had same symptoms as OP. The needle always rested above the middle line on highway trips but stayed on the middle line in town. I changed the thermostat and it stopped happening. The thermostat had a bypass which still allowed coolant to flow but wasn't allowing enough to flow at highway speeds with engine working hard.
Water pump can also cause this.

9icetoo:

At the bolded, not so true.
I've had a thermostat stuck closed on my skoda. Had same symptoms as OP. The needle always rested above the middle line on highway trips but stayed on the middle line in town. I changed the thermostat and it stopped happening. The thermostat had a bypass which still allowed coolant to flow but wasn't allowing enough to flow at highway speeds with engine working hard.
Water pump can also cause this.

Interesting perspective and you might be right afterall.
Some cars do indeed have this bypass, but i doubt Toyota engines do (atleast not in the way we think).
You may have had a bad thermostat that wasn't opening all the way and restricted flow. Not entirely shut completely.
This is one angle i didn't consider in my initial post. Thanks

OP, any update?

Thanks all
I've not driven the car on highway speed since then but these are my observations
1. The fans working directly
2. The two fans blowing in wrong direction
3. Radiator is dirty and some greyish debris flowing on water surface
4. One cooling fan is bad.

Intervention
1. The two fans have been reverted to blow in right direction.
2. Radiator interior has been washed and refill with water(Filling up with coolant is really not affordable now)
3. Electcian has gone for bad fan replacement
4. He will revert the fans to factory mode.
I think this should do.

adesanyadotun:
When in motion , the temperature guage goes above middle but in traffic it comes back to normal.
Car newly acquired
The fans working directly
Water level in radiator not reduced
I noticed a sign of radiator sealant at the edge of radiator opening.
Thermostat still there
Toyota brand

Please what could be wrong and what should I do?

Visit a car wash and tell them to do a radiator flush

Change your radiator cover I have experienced this in my car, I was at a loss cos other components where not faulty until my MECH changed it.

9icetoo:

At the bolded, not so true.
I've had a thermostat stuck closed on my skoda. Had same symptoms as OP. The needle always rested above the middle line on highway trips but stayed on the middle line in town. I changed the thermostat and it stopped happening. The thermostat had a bypass which still allowed coolant to flow but wasn't allowing enough to flow at highway speeds with engine working hard.
Water pump can also cause this.

your are wrong

yes a fully stuck thermostat will cause overheating whether the car is idling or crusing

am sure yours was half stuck


https://www.youtube.com/watch?v=y5p31F_dVJU

Confirm non of the fans are blowing in opposite direction. At stationary or slow moving traffic that will work, but on high way it will work against the air flow which will result to inefficient cooling.

Areaboy2:

Firstly, check to confirm that your fan is blowing in the right direction.
It could just be blowing outwards and this counters/cancels the air rushing in while you are driving, thereby making the heat dissipation of the radiator insufficient. things will work fine when you are in traffic since the air from outside is low as you are on low speed.

This is what I think is wrong.

Wrong fan direction.

Stationery or at slow speed, the wrong direction will not be a problem since the fan airflow is stronger than the ambient air flow. So the fan will be effective.

But when on high speed, the ambient air flow is high while the fan airflow opposes the ambient airflow, its like creating a stalemate. This means the radiator will not have airflow in either direction. This means no airflow, no heat dissipation from radiator leading to overheat.

However, op's description of overheating is vague. Does the needle reach redline or not?

Most cars that have their thermostat removed will have fluctuations in temperature guage especially during the rain/cold seasons.

ZIMDRILL:


your are wrong

yes a fully stuck thermostat will cause overheating whether the car is idling or crusing

am sure yours was half stuck


https://www.youtube.com/watch?v=y5p31F_dVJU

Thanks. We learn everyday.

9icetoo:

Thanks. We learn everyday.

true

what i have observed here it seems like most people dont understand the cooling system of a car, they think the thermostat is for the western world due to cold which is not true, The thermostat is there to maintain the operating temperature irregardless of the outside temperature/climate aka cooling and maintaining a temperature that give better mileage per gallon/litre without causing any temperature change damage to engine block over time