engine over heated

[scorpiox1]

Hi my Renault scenic 1.9DTI last night decided to over heat tho the engine didn't feel no more hot than normal. called rac out and he said it was having a woman's moment. that doesn't really help me as he said i had to drive the 13miles back home ok i got home in one go but it still went into red just as i pulled up outside mine. NO WARNING LIGHTS CAME ON i looked at fan with engine still on and and temp gauge high and fan wasn't working anyone else had this problem? should i replace fan? gonna have a look at wiring later but cant find a wire diagram for it.

Cheers

 

[Belle427]

very difficult to find a wiring diagram but start by checking for power at the fan terminals and work backwards

 

[Mursal]

With the engine stopped and COLD check to see if the fan will turn?

SAFETY:
DO NOT TOUCH THE FAN WITH THE ENGINE HOT.
THE FAN CAN STILL COME ON AFTER THE ENGINE HAS STOPPED.

If it turns, probably the sensor in the engine that controls the fan has gone faulty. Did the cowboy, sorry RAC man, see any fault codes when he plugged in the laptop?

But well worth checking the wiring first.

 

[Peter.N.]

Are you sure it was actually overheating and not just the gauge erroniously telling you it was? If so you probably need a new temperature sensor.

Peter

 

[scorpiox1]

Cheers guys.
the fan does work first i tried moving it and it do so i connected it to some wire and battery and worked. so i now assume its a break in wire which will be a load of hassle finding. so what i was gonna do was connect the fan up so i have to switch it on manually from inside with a in line fuse but this then means keeping a eye on it more.
The RAC guy checked fuses, coolant, revved it to try and get it hot,asked if any warning lights came up, couldn't smell anything coming through the fans inside, and never got a laptop out. his most sophisticated bit of equipment was pliers for the fuses.

How easy is it to find and replace the sensor? tho i cant see that stopping the fan from working?

 

[Djnikon]

How easy is it to find and replace the sensor? tho i cant see that stopping the fan from working?

If the sensor is duffed then it won't be telling the fan that it's needing to come on - hence it doesn't and is in-fact stopping the fan from working.
IIRC the sensor should be easy enough to replace, but you may find it a costly exercise.

 

[scorpiox1]

Cheers Djnikon

what do you think about this idea? what i was gonna do was connect the fan up so i have to switch it on manually from inside with a in line fuse but this then means keeping a eye on it more

 

[Mursal]

Hard wire the fan on all the time when you switch the ignition on, safer that way.

Then get a sensor and or control relay at the next opportunity.

 

[Djnikon]

Mursal is right, if you are going to go down this route then always on with the ignition is best as you would need to judge when it should come on. If you don't get it right or worse, you forget, then it could be catastrophic for the engine.

Get a sensor asap as it's there for a reason.

 

[bhm1712]

if the car is overheating, then it wont be because the fan doesnt work. The fan will only come on after the sensor detects an abnormal coolant temperature (or in some cases, the cylinder head metal temperature)

If the car has enough coolant, and its being driven and not standing in traffic, the fan shouldnt really ever come on unless there is another problem with the engine.

It certainly does sound like the temp sensor is sending a false/spurious signal to the gauge in this case.