Having replaced all the sensors, radiator and pump because the cooling fan wouldn't run long enough to cool the engine I now find I have an electrical fault on the rad sensor.

I have unpluged and shorted the wires as rec ommend and the fan kick in, but went off very quickly, this happened three times and now I have nothing.

I suspect I have a bad connection on the rad sensor circuit but would like to check the earth for this circuit, can anyone advise where this earth is and if there are any other points to check.

Just put another earth in, it will do no harm.

Cheers

SPD

OK got a bit further today, it would appear that the cable I used to test the circuit from the fan sensor had got to hot and melted through I know this because the second cable I made up got very hot as soon as the fan was running.
I tested with a screw driver and the fan will run fine however the screwdriver gets warm I guess indicating a fault with the fan.
Also the new rad sensor seems not to be working at all now (it was originaly).

Please could someone shed some light on the following

Screwdriver getting warm indicating fault with the fan (which seems to work ok) and not the wiring
Is it possible for this to knacker a new rad sensor.

All advice welcome

The fan bearings are on the point of seizing. The motor is drawing a huge current hence the heating up of things electrical.

Its possible the back feed has screwed the thermal switch in the rad.

I always test a fan switch connector with a an opened out paperclip, you can see it glowing if the draw is too much.

Cheers

SPD

Thanks for advising, this has kind of confirmed my suspicions.

I also think the fan is running way to slow so this would confirm your thoughts as well.

Do you know best place to get a new fan.

alfa156v6 said:

Thanks for advising, this has kind of confirmed my suspicions.

I also think the fan is running way to slow so this would confirm your thoughts as well.

Do you know best place to get a new fan.

Click to expand...

Fan running slow is a good indication of bearing trouble. It doesn't turn fast enough to cool either, leading to overheating, which is how this started.

Fluffy might be cheaper than Fiat for a new motor.

Cheers

SPD

Cheers, just wondering is it worth running a new earth and if so where from and to, is this likely to cause the hot paper clip.


Oh and who/what is fluffy????

alfa156v6 said:

Cheers, just wondering is it worth running a new earth and if so where from and to, is this likely to cause the hot paper clip.


Oh and who/what is fluffy????

Click to expand...

An additional earth from the motor to the chassis will do no harm, but it will not solve your (excuse the pun) current problem.

Fluffy the Impaler, of this parish AKA Big Mick http://www.eurocarcare.co.uk/.

Purveyor of parts to forum members at discounted prices.

Cheers

SPD

In dispare now, I have replaced the sensor with the old one and fitted a new fan and still no joy.

The fan will work if I short the rad sensor terminals but not when the engine is hot.

Any help greatly appriecated.

cooling system bled correctly?

So far as I can tell, I have open the single bleed valve filled up with water until this has fluid visable.

Is there another way of bleeding the system.

Where did you attach the other end of the additional earth?

Cheers

SPD

alfa156v6 said:

So far as I can tell, I have open the single bleed valve filled up with water until this has fluid visable.

Is there another way of bleeding the system.

Click to expand...

filled up the bleed valve ?

expansion tank should be filled up then bleed valve opened and let the water come out of there by itself and should be sealed when no more bubbles are in the water

Ash

rallycinq said:

Where did you attach the other end of the additional earth?

Cheers

SPD

Click to expand...

Didn't fit a new earth in the end as I didn't know where to conect it from and too.

To confirm I filled the expansion tank with water with the specified amount of fluid whilst the cap from the bleed valve was removed.

I have noticed a hissing from the filler cap when the engine is hot what impact is this likely to cause.

alfa156v6 said:

Didn't fit a new earth in the end as I didn't know where to conect it from and too.

To confirm I filled the expansion tank with water with the specified amount of fluid whilst the cap from the bleed valve was removed.

I have noticed a hissing from the filler cap when the engine is hot what impact is this likely to cause.

Click to expand...

the missing is either a dodgy cap or its just venting the extra pressure out

is this missing all the time or every so often ?

whitz said:

the missing is either a dodgy cap or its just venting the extra pressure out

is this missing all the time or every so often ?

Click to expand...

Difficult to tell with the engine running as I can't hear it it is only when the engine is switched of you notice it.

rallycinq said:

An additional earth from the motor to the chassis will do no harm, but it will not solve your (excuse the pun) current problem

Click to expand...

Do you splice into the existing earth or just run an additional from the motor housing to the chassis

Caps are cheap enough, get a new one.

Is the radiator getting hot all through, or just at the top.

The bottom should be cooler but not stone cold.

Cheers

SPD

rallycinq said:

Is the radiator getting hot all through, or just at the top.

The bottom should be cooler but not stone cold.

Cheers

SPD

Click to expand...

Yes hot to the touch at the top and little cooler at the bottom but niether are burning hot.

Sounds like a cap problem then.

Cheers

SPD