Engine transplant now over heating AGAIN!

I bought my C3 with major engine failure. I was told it was a snapped timing belt but turns out it was an overheated engine and con rod failure (shattered). I discovered this during an engine transplant and having put the new engine in I am still having over heating issues. I replaced the thermostat and have flushed the radiator. The radiator fan never kicks in but appears not to be broken. I noticed when i removed the original engine that the temp sensor (blue one going into engine block just behind thermostat housing) wasn't plugged in. Is this the root of the overheat issue? I searched high and low to find a connector to plug into it but nothing there. Im assuming the wire has been ripped out and could really do with a diagram to see but cat find one anywhere. Cheers in advance. Andy

Hi Andy, with regards to finding a diagram, the blue C3 Haynes manual has diagrams for the wiring, you can find them on eBay. When I get home, I can take a look for you, but you may be better off having a copy to hand for inspection.


Does the car have air-con or climate control and does it work?

It has air-con and yes it works.

I've power probed the fan and that works. Still having driven the car for half an hour today the fan didnt come on at all.

To be clear i'm not getting any warning lights or anything to suggest it knows its over heating. It just feels VERY hot. I do mean very hot. If you put your hand on the upper timing belt cover or on top of engine it will burn. If I turn the heating back down to low I get steam (only slight) from the radiator too.

If I turn the heating back down to low I get steam (only slight) from the radiator too.

You shouldn't get steam from the rad because its a sealed system. There is a problem with the rad.

In this topic about a cooling problem https://citroenc3owners.com/citroen-c3-q ... -t646.html, Missing Lincs suggests the use of temperature measuring strips to get a true indication of the temperature in the cooling system, which may be useful?


If the problem of overheating carried over to another engine, it would suggest the problem lays with something that didn't get changed with the engine. Anything from the engine ECU, cooling system, or binding brakes/wheel bearing?

I've power probed the fan and that works. Still having driven the car for half an hour today the fan didnt come on at all.

How many wires are on the fan electrical connection? Can you take a picture?

Sputnikk1984 wrote:Engine Size: 1.6 (16v)

I know is a strange question, but did you fit the correct engine......?

Sputnikk1984 wrote:The radiator fan never kicks in but appears not to be broken. I noticed when i removed the original engine that the temp sensor (blue one going into engine block just behind thermostat housing) wasn't plugged in. Is this the root of the overheat issue? I searched high and low to find a connector to plug into it but nothing there. Im assuming the wire has been ripped out and could really do with a diagram to see but cat find one anywhere.

The temperatures sensor on the coolant outlet housing gives a signal to the ECU which controls the fan speed.

The other sensor, the one attached to the head sends temperature info to the dashboard.


If the ECU sensor is not working you would normally loose air con or climate control.


The ECU sensor should have a blue plug and the 2 wires just go back to the engine ECU on pins E4 and D4 of the big ECU multi plugs.

I have solved the issue thanks. The new engine had the second sensor (which the fiirst didnt have) so there wouldnt be a connection for it.

Fan works just fine and kicks in if I unplug the coolant temp sensor.

Conclusion was in the resistor.

Cheers.

Sputnikk1984 wrote:I have solved the issue thanks. The new engine had the second sensor (which the fiirst didnt have) so there wouldnt be a connection for it.

Fan works just fine and kicks in if I unplug the coolant temp sensor.

Conclusion was in the resistor.

That is great news!

Thanks for the update.