2006-2009 Facelift model - Add temperature gauge?

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My Name: SiriusHardware

Contributor
Posts: 23
Joined: Mon Apr 07, 2014 6:52 pm
Model: C3 2006-2009, Facelift model
Year: 2009 (59)
Engine Size: 1.4
Fuel Type: Diesel
Mileage: 75000
Trim Level: Airdream+
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
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Let me explain the reason for this question first:-

A little over a week ago we noticed a small wet patch under our parked 07 reg C3 1.4Hdi. It didn't smell of anything, and didn't look like oil or brake fluid. We couldn't see where it might be coming from so we drove on another 10 miles before our next stop, at which we looked again: This time, a steady drip, drop every two seconds or so. At this point I realised the coolant expansion bottle was empty. I put my hand on the radiator - stone cold. We basically had no coolant at all. At NO point had we had any kind of warning from the car, and as far as we can see the car - facelift version of the original C3 - does not have the bargraph temperature gauge that the original version appears to have had.

We had a big multi-pack of bottled table water in the boot (lucky!), so we filled the car back up and gingerly drove another ten miles hoping to limp home, topping up the water every now and again. At the next stop the water came flooding out faster than we could put it in, so that was it, game over. Rather than blow the engine (which, amazingly, was still running as sweetly as could be), we had it lifted by the AA and recovered back to the house.

We already reckoned it was a hose, and this was just confirmed by our garage who also said that owing to the position of the break in the hose - above the starter motor - the starter motor had been heavily flooded and had rusted badly during the week the car had been standing awaiting a slot in the garage, so it's likely that as well as the hose, we will need to replace the starter motor as well.

My main beef about all this is that we got absolutely no warning about the loss of coolant and temperature rise, and for that reason I want to look at the possibility of adding an independent temperature gauge to the car so we'll always have some kind of early warning if a problem like this occurs again. I assume the ECU should have come up with a warning the way it does when there's a sidelight off: It didn't, so frankly, I don't think we'll ever be able to trust it to warn us about coolant problems.

The earlier version of the car did have a temperature gauge and presumably even on this version the ecu still needs to be able to monitor the coolant temperature. Does that mean I should be able to find a temperature sender (which outputs a gradual change as the temperature changes) already fitted? I know a bit of electronics, so converting that change into a meaningful reading or bargraph display wouldn't be too hard for me as long as the temperature sender exists for it to get a signal from.

If there is such a sender in this version of the 1.4 Hdi C3, where is it?

While I'm asking, is there already an aftermarket / add on temperature gauge kit for the C3 (2006-onwards?)
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My Name: Arfur Dent

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Posts: 3433
Joined: Sat Jul 23, 2011 3:47 pm
Model: C3 2002-2005, Original shape model
Year: 2002 (52)
Engine Size: 1.4 (16v)
Fuel Type: Diesel
Mileage: 100000
Trim Level: Exclusive
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Engine name: DV4 16-valve diesel (90 PS)
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Been thanked: 121 times

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If there is such a sender in this version of the 1.4 Hdi C3, where is it?
There is a dash warning for temperature and the BSI monitors engine coolant temperature on all years of C3 HDi engine, but it may be easier to use something like this:
temperature sensor and display
temperature sensor and display
the sensor could attach to the outside of the top radiator hose, or some other suitable point in the cooling system. This would avoid having to interface with the CAN bus.


Temperature warning
Citroen C3 2006 coolant warning
Citroen C3 2006 coolant warning
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My Name: SiriusHardware

Contributor
Posts: 23
Joined: Mon Apr 07, 2014 6:52 pm
Model: C3 2006-2009, Facelift model
Year: 2009 (59)
Engine Size: 1.4
Fuel Type: Diesel
Mileage: 75000
Trim Level: Airdream+
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Been thanked: 2 times

Post

Thanks for the response - I can't say that I have ever noticed that symbol in amongst the mass of lights which light up and go out when the key is turned - we haven't got the car back yet so I can't look for it just now, but I will be looking to make sure it is working. Are these indicators LED based or filament lamps? (In other words, could the bulb have failed?).

Thanks for the suggestion of the stand-alone thermometer kit which could be one way to go, but I think the top of the radiator wouldn't be the ideal place for the sensor, as the radiator was stone cold when checked in the situation I described (due to it having no water in it!). Even when working normally the radiator only has coolant flowing through it when the engine is hot enough for the radiator thermostat to open, so you wouldn't get a very true coolant temperature reading from there when the thermostat was closed. Somewhere near the radiator thermostat on the engine itself might be a better bet, as you say.

But better still would be if I could tap off the signal from the existing sensor that the ECU reads, because the sensitive part of that actually sits in the coolant flow and gets the most immediate and accurate reading of temperature from the coolant (in theory, and if it's working). I doubt whether the sensor communicates with the ECU via a digital stream like CANBUS, (although I could be wrong about that!) it more likely just has a resistance proportional to the temperature it is sensing, and that resistance (or the voltage across it) could easily be read by an electronic voltmeter or a microcontroller with an analogue input and converted to a bargraph indicator output (as on the earlier C3) or a numeric readout of the temperature.

What I don't know is where the Sensor used by the ECU actually is on the 1.4HDi engine. Anyone know? (A picture would be really helpful).
User avatar
My Name: Arfur Dent

Guru
Posts: 3433
Joined: Sat Jul 23, 2011 3:47 pm
Model: C3 2002-2005, Original shape model
Year: 2002 (52)
Engine Size: 1.4 (16v)
Fuel Type: Diesel
Mileage: 100000
Trim Level: Exclusive
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Engine name: DV4 16-valve diesel (90 PS)
Has thanked: 319 times
Been thanked: 121 times

Post

Are these indicators LED based or filament lamps? (In other words, could the bulb have failed?).
LED

Image

https://citroenc3owners.com/citroen-c3-t ... -t531.html

What I don't know is where the Sensor used by the ECU actually is on the 1.4HDi engine. Anyone know? (A picture would be really helpful).
The engine coolant temperature sensor is on the thermostat housing assembly, right hand side of the engine bay. You need to remove some air pipes to get a good look at it.
Citroen C3 engine coolant sensor on thermostat housing
Citroen C3 engine coolant sensor on thermostat housing


It will be great to hear how the project goes! :D
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