Citroen C3 Overheating / Coolant Bubbling Expansion Tank

[GiveMeABreak]

2006 C3 1.4 Petrol Desire

My friend's C3 has been playing up last week. Going into limp home mode and engine fan going full blast. He managed to drive it to his local garage but they didn't have the Lexia kit and couldn't work out the issue. He was therefore going to get it booked into the main Citroen dealers next week. I went to the garage on Friday with my Lexia and diagnosed it with code P0485 (Cooling function incorporated into engine ECU permanent fault) I managed to clear this fault and he drove it home about 3 miles carefully no problem.

Today, he decided to take it to the local petrol station to get some fuel when it went into limp mode again, but he managed to drive it home. I called up today with the aim of resetting it again ready for him to try and drive it to the main dealers next week, but for some reason (maybe unrelated) my Lexia started a diagnostic but there was no communication with the BSI or any ECU. While we were trying to run the diagnostic, he had the engine idling for a while (in case the Economy Mode was kicking in and playing up), but the engine warning light came on again and the Engine Temp too High warning with it. He switched the engine off and went outside to hear the car gurgling away. We carefully lifted the hood and coolant was bubbling out of the expansion tank all over the place. It was a rusty brown colour. Nothing was leaking out of the radiator or any other hoses. When the gurgling had settled down, I carefully checked the expansion tank cap and confirmed it was on tight.

His local independent garage did an engine rebuild last year after the cam belt went - but when I asked whether they replaced the water pump - he didn't think so - awaiting confirmation on Monday.

So - obviously there was nothing wrong with the temperature sensors - they seemed to be doing their job properly!
My initial thoughts are:
Failure of water pump?
Head Gasket Failure?

Has anybody had something similar happen and if so, what is the likely prognosis and potential cost? The issue now for him is how much is it estimated to repair against the value of the car, against needing to get it running to do anything with it.

Any pearls of wisdom gratefully received in advance

[Lighty]

Your C3 issue will depend a little on the engine it has fitted, on the later tu engine the car has an electrical thermostat, and this is most likely the problem,I.e stuck shut.
Should be easy to see if the radiator is cold when the car starts to overheat.
Another possible fault is that the cooling fan is not operating, you can try an actuator test with your Lexia just to see.
Some C3's have the fan Ecu built into the fan motor, and this can fail. Lexi then comes up with the exact fault you describe, as the program was not written in such a way as to explain this.
I have seen many C3 engine ecu's "spiked" by garages putting 12v to the plug on the temp sendor, trying to see if they can make the fan work.
This will take a seperate repair to fix, as the Ecu doesn't know what temp the engine is at.
This can also be looked at in parameters on Lexia by monitoring the temp as the engine gets hot.

[GiveMeABreak]

Thanks Lighty - Lexia won't connect to it at all at present as mentioned in my post, so can't do anything with it. I'm sat here wiping laptop for a clean OS and Diagbox install. Once I have that all back up and working, I'll try and connect up to our C5 and C3, before trying it on my mates sick C3. The engine is a 1.4i 75 (TU3A) Manual by the way.

[GiveMeABreak]

Well my mate is having a recovery truck take it to the main dealers on Thursday. I'll post back the outcome as soon as he knows in case it helps others.

[GiveMeABreak]

Update 1: Car was recovered to main dealers yesterday and was looked at today. Spent 2 hours on the diagnostic kit ( !) to try and find the issue - nothing found yet except "they tightened something up and it's working now" (?) Will post another update when he hears back from them tomorrow.

[GiveMeABreak]

Update 2:
Seems all temp sensors were fine. Investigation revealed tappets had been incorrectly tightened by previous garage when rebuilding after cam belt went - some were too loose and some too tight. Seems to have corrected the over heating, so hopefully that has been sorted.
Edit: Engine Management Light back on after about 60 miles. They are in dialogue with main dealer again.

[GiveMeABreak]

Update 3
Well finally turned out to be the Air Intake throttle valve housing. This was replaced and has now seemed resolve the overheating.