Technical Any Ideas?

[daztap]

Car was nearly over heating. Had water pump changed and had the radiator flushed and bleeded up. Thought i'd curied the abnormal temperature movement. Week later, its playing up again. Temp needle goes right up 3 quarters of the guage. Fans working. I get a sound of running water behind the dash when i start the engine up and rev it a little, then it stops. Had a head gasket block test and nothing was wrong. What is the problem here?
Oh and heating is clap cold.

 

[BRAVARulez]

Maybe your temp sensor is faulty and shows you wrong temperature. Try to check your sensor and if its faulty replace it with one from scrapyard or buy a new one. I am attaching a foto how the sensor looks like and how can you measure it.

 

[daztap]

Thanks alot for the Photo and help but if its faulty and its showing the temperature as hot shouldnt the heating be hot even though its reading wrong?
do you recon it could be a faulty thermostat?

 

[Xen]

Thanks alot for the Photo and help but if its faulty and its showing the temperature as hot shouldnt the heating be hot even though its reading wrong?

no because the heating relies on the temperature of the coolant - coolant may be cold, hence cold air, but the sensor is inaccuratly reading it as high.

The water noise is because you still have air trapped in the cooling system - try bleed it again.

 

[daztap]

wel this is soundin better than i thought. so it sounds like a faulty temperature sensor?
i didnt quit understand tht diagram tbh can any 1 simplify it for a retard =]

 

[Xen]

if you disconnect the sensor and use thermometer to test the temp of the coolant (or if you do it from cold if the car hasn't been run all day, the coolant temp should be close to that of the air temp) and a multimeter to test the sensors resistance, the resistance and temperature should meet along the line of that graph. if it doesn't, the sensors giving a bad reading.

for example, your doing it from cold and the air temp is 20c. The resistance should be showing about 2300ohms according to the graph - if its not, its faulty.

 

[jug]

i bet its head gasket failure, it always is on the 1.2

 

[daztap]

Looks that way Jug, white gunge under oil cap and loadsaa white smoke coming from exhaust pretty odds on isnt it? lol
whats are the chances of it going again if i get it repaired?

 

[jug]

given enough time it will go again, thats the 1.2 engine for you. i had my GF's head gasket done on her 1.2 last year, if we get 2 or 3 years out of it then i'm happy. it only cost me £170 including a new timing belt at my local garage so it isnt a big deal really.