Hi, I have recently fitted a new thermostat to my 95 SX cinquecento. However I may have damaged the temp sensor as it doesn't show any reading on the dash guage. Is there a way to test if it is working?
In the haynes manual it says that the coolant resistance is 10K ohm at 0C and 5K ohm at 20C and so on, is this the resistance that the sensor reports?? If so I do have the equipment to test for this.
Also anywhere I can get a replacement apart from fiat as it will cost £33 for a new one. Also does anyone know what tool you can use to remove the sensor while the thermostat housing is still attatched to the engine?

Any advice is welcome as I have now hit a :bang:.
If it is working I can seal it but I need to know how to remove it safely.
If I drain the coolant would I be able to reuse the gasket? I just fitted a new one today.

there are two sensors for the temperature.

the gauge one is at the timing end of the engine, on the back of the block... rats, you have an 899.. erm.. i think its the left hand side as you look at the engine, just in front of the inlet / throttle body cap thingy (bob!) Wire comes out and goes 90degrees with a cap thingy on it.. im ace at describing these!

Anyyway, to test the guage - disconnect it and touch the wire to ground - the gauge should hit the top. To check the resistance of the sender, disconnect it and then probe between the centre connection of the sender and ground. It should read the various ohms that haynes says.

If you do need a new one, they are around £5 - not £33. You must've been looking at the ECU temperature sensor which sits in the inlet manifold on the sporting.. and im guessing on top of the thermostat on the OHV engine.

hope this helps!

Cheers.
Yes I'm in a 899cc, and it is the sensor on the thermostat that runs to the temp guage. (it has a blue cap on it)
Where would I get a sensor of this type for £5 as I was quoted £33 from a fiat dealer?
Any idea what tool would remove it without removing the whole thermostat housing again? Will the gasket be reusable? as it is new and fitted today.

It's not the guage sender thats on the thermostat housing, thats the ECU sensor. It has nothing to do with the temperature gauage.

7588882 is the part number of the gauge sender.
7762299 is the ECU sensor part number.

If its the gauge thats not moving, then its nothing to do with the sensor on the thermostat.

Checkout haynes, job 6, number 9, secton 3.5.

Thanks very much, you are ofcourse correct.
So do you think it could be that the coolant hasn't reached that sensor?
I only left it running for about a minute or so. And the header tank was looking full after only about 1.5 litres of coolant was poured in.

Any advice is more than welcome. I do have a manual but as I have never worked on any car before I am a bit bewildered.

I fitted the thermostat housing, sensor, and then opened the bleed screw near the header tank, left it open until water started to trickle through, refitted the screw, topped up tank a bit, fitted the cap and then started the engine. No reading on the temp guage.. Although it was working before I drained the coolant.
Also I don't seem to have the bleed screw at the heater matrix that the haynes manual sayes should be there.

Thank you for your help so far, anything else you can tell me would be very helpful.

1.5 litres isnt very much at all, the system should hold around 4.8litres.

With regards to bleeding the system, i can't really add anything that's not been said in haynes as i've never worked on the 899 before. Tom (arseofbox) should be able to help you out though i as i know he recently put a new radiator on his 899.

Try disconnetion the wire from the gauge sender, touch the wire onto the block/ground. The guage should hit the top.

Then try probing the connection on the sender unit, and ground - check that it's showing resistance.

Running the engine for a minute or so, i wouldn't expect the gauge to move. You could try submergeing the sender in hot water to see if it gets a reading. Although as well as having the wire connected to it, you'd need to secure another wire to the outer part of the sender and attach that to ground (normally grounded by the fact that it's screwed in!)

Thanks,
After properly reading the manual, it appears that not all cinq's have two bleed screws.
I am due to get the radiator flushed in a week or so, plus I am not sure how much water was left in the radiator, as I just remembered I only removed the hoses from the thermostat housing and not the bottom of the radiator.
So basically it looks like I have just got to remove the temp sensor and fit some plumber tape around the threads to stop it leaking.
Doh, ah well I suppose it is a learning curve.
Any suggestions for a good water tight seal on the thermostat temp sensor??

Most helpful, thanks.

is it leaking from the ecu temperature sensor? erm.. i dunno, did it have any seals that were meant to go back on that could've perished? Failing that, just bung some PTFE tape round the threads and hope for the best.

Like i say, having never worked on that type of engine i'm not 100% with bits like this!

Yep, that should sort it. I couldn't for the life of me remember what that tape was called.

Probably get it fixed by tomorrow evening.
Car cost £165, needed 2x front tyres, MAP sensor was not connected causing it to idle erratically, thermostat needed replaced, and needs a new air hose, so basically it has cost me in total about £300 -> £350 for a fully working cinq, not bad. Just needs an oil change/ flush and the same with the radiator just to be sure.

Thanks again for the help and advice.

no problem

Good luck with it

Well ended up using thermite gasket sealant seems to have done the trick, and yes the temp guage does work I just hadn't ran the engine long enough.
Only one problem left, and that is the accelerator seems to be a bit sticky, doesn't seem to return to the proper position. Which can be a problem changing gears at low speed.
But get that seen to on Monday or Tuesday by a proper mechanic.

The accelerator problem could well be a small rubber device (no sniggering at the back) which is supposed to be on the end of the outer cable with the inner cable passing through it. It can become detached from the outer cable and jam the inner cable from returning smoothly.

Cheers

D

yes I have checked this rubber cover seems ok as it still overrevs when I pull it away from its normal location.
Have just oiled the return spring on the throttle housing and also the cable slightly.
If that doesn't work I may need a new spring, the car has not been maintained very well by previous owners.
In fact does anyone know which colour wires go to which pins on the connector for the radio/cd player? As the girl that I bought it from has cut off the fiat connector, which is rather annoying.
Any pics / wiring diagrams are most welcome.

Ok, so I have now fixed my cinq, all it needed was an airhose reconnected, a new thermostat, two new front tyres, the MAP sensor reconnected and the throttle cable loosened off slightly.
So everything is looking good, just need a new header tank cap.
So I recon the car has cost me around £300 or so in total, very happy with it, although it does seem to pull away a bit better than a one litre corsa.

Cheers to everyone who gave me a helping hand.