High temprature problem

[tronky]

Hello

I recently bought a 2.0 Megane II sedan for my wife, it's an 2007 model.

Today while we were in another city, I was driving and saw that the temp needle is going up.....a few seconds later, it was about to enter the danger zone.

I switched off the a/c and the engine and let the car cool down for a few minutes.

Later, when I switched the engine on again, it's a little higher than normal and began to decrease until it reached the normal sign.
5 minutes later I turned on the A/C again and nothing happened with the temperature again, although I was driving in a traffic jam in which 4KM took me 25 minutes to pass.

Nothing happened until I came back to the city I live in, which is almost 100KM away from where the problem happened, and during the last 15KM of my journey back home, I increased the speed to almost 150KM/H then I noticed that the temperature needle is 1mm lower than normal......when I arrived and parked for 2 or 3 minutes it was still below normal, I tried to push the RPM to 5K and the needle went below further, after I let go the gas pedal, it went back to normal again.

Please see the pics








I'm really confused of what might have caused that, at the beginning, I suspected the cooling fan not going into the second speed, but later I made sure that it goes into the second speed normally.

Any ideas ??

[tomalamix]

thermostat problem maybe. im not sure how it works on the petrol engine but for the symptoms you're telling us maybe its malfunctioning...

[davelowe]

What was the ambient temperature?

Check the coolant level.

You may have a sensor problem, or the coolant pump could be to blame, or maybe a leak. Very difficult to tell from your initial post.

[tronky]

What was the ambient temperature?

Check the coolant level.

You may have a sensor problem, or the coolant pump could be to blame, or maybe a leak. Very difficult to tell from your initial post.

ambient temperature was around 80F

coolant level was OK and there's nothing indicating a leak so far.

How can I know if it's the coolant pump ?

Thanks for your response guys.

[Scenic]

Could also be a possible airlock in the system which if that would require bleeding.

[tronky]

Could also be a possible airlock in the system which if that would require bleeding.

could be......
One thing that you reminded me of, when the overheating happened, I parked and turned off the engine, let the car cool for a few minutes then I opened the coolant reservoir cap to check the coolant level more clearly thus some pressure came out. Then everything went normal except for the temp needle to go below normal position.

[tomalamix]

the pump is working all the time, the thermostat allows the cooling liquid (water + antifreezing) to pass though, if the pump have, for some reason, broke some parts off could be failing to make the coolant to circulate...

cheers

[Scenic]

The usual way to bleed the system is to get the engine at running temp,speed engine up and open bleed valve till constant flow thro bleed valve then close valve, providing that an air lock is the real problem, bleed valves are usually on top hose and heater pipes.

[tomalamix]

the bleed could help but if you need to bleed the system is because you have a leek somewhere...does your coolant lever is ok?

cheers

[tronky]

The car has been at the Renault agency since yesterday afternoon and yet they didn't find what have caused the overheating

[tronky]

Today I received the car back, they told me to change the fan resistor.....and they cleaned the A/C compressor fins.

They told that the resistor seemed to be not operative well.....I didn't really understand that Indian guy who told me.

Anyway, I took it for a ride of around 200KM today and the temp. needle didn't exceed the normal indicator, but sometimes it went below

What was really impressive is the A/C performance, it was freezing at the maximum settings which I used to select to have good conditioning, however, today the conditioning was excellent.

Thanks for your help guys.

[tomalamix]

well, the needle shouldnt go below the 3rd stripe, it should sustain there. for now no problem but we never know

cheers

[tronky]

After 10 days of testing, so far no overheating but the needle still goes below 3rd stripe.

This happens usually at night when it's not hot and without speeding or A/C on, if either speeding or A/C is on, the needle is at the 3rd stripe.

Any hints ?

[tomalamix]

thermostat... It lets the coolant pass even if it would be shut

cheers