Temperature gauge issues

[box of bits]

Firenza 2300

Temp gauge clock working as when I short the sender wire out the gauge needle goes to hot.

I have changed the sensor unit for three others -- still no joy

I have tried warming the sender disconnected from the engine and connected to the sender wire - no joy

Strangely when I switch on the ignition but do not start the car the needle does crawl to Cold??

So - what voltage should I be getting at the end of the sender wire which connects to the sender unit ? mine seems to fluctuate -- is that normal?

[shamm]

Voltage comes from regulator behind dash and yes they do fluctuate a bit.

Sound like all the sensors you have tried are broken

Worth also checking the sensor is not in an airlock, remove when cold and check water is present in hole!
Also check water ways in manifold are not silted up.

[box of bits]

Hi Mate - much appreciated -- bit more info

Water flows freely, -- I have ha about 5 now -- 3 x new ?

Engine does not over heat and heater works --

Will try heating the sensor up again on all 5 !!!!

IF anything else comes to mind -- please let me know -

thiking about changing to a caillery type and sacking this off - but it does seem a shame

[1972nail]

Look at the condition of the connections in the bulkhead connectors in the fuse box. These very often get corroded and dirty causing difficult to diagnose faults.

If they are corroded take the whole fusebox out and dip in citric acid for a few minutes, dip the connectors as well. Make sure that all is completely dry before connecting up again.

[shamm]

Worth checking that the manifold is not somehow isolated from the engine earth as this forms the circuit for the gague!

[box of bits]

Thanks matey -- now then you may have a point there -- so how would I ground the inlet? run a wire from where to where- one of the securing bolts to earth?

[shamm]

To test just connect jump lead from battery - terminal to the outer of the sender or the manifold itself

[box of bits]

give it a go tomorrow so stand by !!!

[1972nail]

If the earth is poor on the manifold just slacken off and re tighten a couple of he bolts, that should remake the connection.

[shamm]

Unless someone has used fibre washers!