Important! : Help!! Fan constantly on and car thinks its overheating...

1. Hypaadanny L-plater Joined: Jun 2016 Cambridge Posts: 30 Saxo Vtr 8v 2003 black and green

   #1 30th December 2016, 05:38

   Right last week i was driving and my fan came on and the red warning light on the temp gauge came on and they both stayed on.
   Everytime i turn engine off andd on even when its cold, the light and fan comes on.
   So thought ok get new thermostat and flush and bleed radiator. Done this properly of courae.
   That didnt work and car thinks its hot. But rad water is cold same as rad itself.
   Drove to southend and back (60 miles each way) no problems.
   Also when i turn engine on it kind of struggles and i have to keep reving it to build rpm and it tries to die when i do so, and it stinks of petrol.
   Plugged a cose reader in and it came up something like engine coolent sensor short circuit. No 100% on that btw.
   I hust gave no idea what it could be.
   Rather coolent temp sensor or the wires for it maybe??
   
   Advice would be grateful.
   
   Thanks
2. P-Courty Established Member Joined: May 2008 Wirral Posts: 1040 Blue/White Flatarch Saxslow Ph.1

   #2 30th December 2016, 08:29

   Sounds like airlock causing it to try and die and temp sensor dead because of it, hence the high temp reading and the fans staying on. Or possibly if it's got so hot the heads started to warp and may get alot more expensive, cheapest option go get a new temp sensor and clean the new stat and check it in boiling water again then put them both in, fill up, bleed through, take it for a drive, next day check water level and rebleed and top up.
3. VTR_Craig Saxperience Forum Bum Joined: Apr 2007 Lincoln/Newark Posts: 2673 Mercedes C220, Scooby, Saxo VTS

   #3 30th December 2016, 09:18

   for the price of a coolant temp sensor its worth trying that first.
   
   because it says its a short circuit, it maybe down to the wiring.
   
   When the temp sensor doesn't work correctly, the ecu doesn't know what temperature the car is at and if it is overheating, so it will turn the fans on to make sure the car doesn't overheat.
   
   When you wire a fan over ride switch onto a VTR, you basically put a switch in the circuit of the coolant temp sensor so when you flick the switch, the car doesn't know what temperature the coolant is at and therefore puts the fans on incase.
   
   If the car doesn't know what temperature it is at, it wont give the correct fuel mixture so it maybe over fueling, this maybe why the revs are dying and you are getting a fuel smell.
   
   Its only an educated guess but for the price of a coolant temp sensor its worth a try
   
   double check when the engine is nice and warm that the coolant is flowing around the system. (interior heater hot, all radiator hoses hot etc) could be a sign of blocked heater matrix, water pump or even head gasket issue
4. Bedford126 Saxperience Post Whore Joined: Jul 2010 Morley, Leeds Posts: 8469 Civic ep3 type r powered by TDI NORTH

   #4 30th December 2016, 13:16

   Not sure what the 2003 vtr temp sensor is like but if it's the big blue/green sensor on the rad then. Unplug the sensor on the rad if the fan goes off then it's likely to be the temp sensor. In the plug there should be 2 wires jump the wires and see if the fan comes on. If the fan comes on then you know it's the sensor in the rad that has the fault . If nothing happens when you unplug the sensor then you can make a separate loom yourself to run the fan, I made one for both Ali and Matt on here they aren't difficult.
   
   As for the post above, there is no need for a manual switch you can just make a full circuit from the fuse box to the temp sensor then to the fan as a switch, I'm not sure the ecu reads the temp sensor in the rad I think it's all controlled by the thermostatic switch in the rad (temp sensor).
5. Hypaadanny L-plater Joined: Jun 2016 Cambridge Posts: 30 Saxo Vtr 8v 2003 black and green

   #5 30th December 2016, 13:38

   Thanks for the replies. Heaters work fine and pipes are warm as normal so il try sensor and see if it works
6. Bedford126 Saxperience Post Whore Joined: Jul 2010 Morley, Leeds Posts: 8469 Civic ep3 type r powered by TDI NORTH

   #6 30th December 2016, 13:48

   Just unplug the sensor mate if the fan goes off then you know it's the sensor.
7. Hypaadanny L-plater Joined: Jun 2016 Cambridge Posts: 30 Saxo Vtr 8v 2003 black and green

   #7 30th December 2016, 14:29

   Tried that and it didnt go off i dont think
8. VTR_Craig Saxperience Forum Bum Joined: Apr 2007 Lincoln/Newark Posts: 2673 Mercedes C220, Scooby, Saxo VTS

   #8 30th December 2016, 16:19

   Quote:

   Originally Posted by Bedford126 As for the post above, there is no need for a manual switch you can just make a full circuit from the fuse box to the temp sensor then to the fan as a switch, I'm not sure the ecu reads the temp sensor in the rad I think it's all controlled by the thermostatic switch in the rad (temp sensor).

   I meant if you were wanting to put a manual over ride switch in. I did it on my VTR that I used on trackdays to keep it cool on cool down lap