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Discussion Starter #1
Hi all,


In more detail; it's a SWB 1.9 TDi 104 with an 04 plate, almost 200k miles. Cam belt and water pump re-done last year.

Three problems, may be connected.

First: Engine never runs as hot as it should according to the instrument cluster temp gauge - the gauge never shows hotter than 80-85' no matter the time of year / weather.

Two: Radiator fan runs and keeps running from cold, as soon as the engine starts. I've replaced the ambient air temp sensor (in front of the rad, behind the front grill) with a new unit and seen no change.
Multimeter shows a continuous path to earth / supply voltage on the sensor leads although wiggling the wires with both old and new sensors connected occasionally caused the fan to stop running when the engine was cold, as it should(?). Possibly the wire connection to the sensor plug itself is damaged, not the sensor? Resistance of the circuit was about 2 kilohms I think.

Third: The instrument cluster temp gauge occasionally stays on its zero stop even when the engine has been running for a while - until I fiddle with the heater controls (plain heater, not A/C). When I change the heater temp, the gauge suddenly moves into the more normal (70-80') range within a few seconds. I've been told it might be a stuck thermostat, but the top and bottom coolant hoses both feel warm to the touch after the engine has been running for a while.

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