beyerdbx

does this sensor have anything to do with the cold start valvue. I have a 1987 audi with a NF engine, I was told there is no thermal time switch in this model. Having problems starting car cold.

rooster 2

I have an NF motor. I don't know if the water temp sensor has anything to do with the cold start valve.

However, the water temp sensor has two functions. It feeds a temp signal to the instrument cluster to show water temperature, and it also has a mysterious function, that if broken, you won't be able to start your motor. I have experienced this first hand.

beyerdbx

thanks rooster, thats what i needed to hear. But, where can i find the water temp sensor under the hood.

rooster 2

beyerdbx.......the water temp sensor is found on a fitting just below where the top radiator hose connects to the engine head. It threads into the bottom side of the fitting. Size wise it is about 2 1/2" to 3" long. It has a four wire connector, with a large black rubber boot that covers most of the sensor to keep out dirt and moisture. It is in kind of an awkward position to get a wrench on it. Since it is rather large a 10" adjustable wrench is what I use to work on it. Since the sensor screws into a cooling system fitting, removing the sensor allows coolant to pour out. It is best to have a new sensor close at hand to replace the old one you are removing. When replacing, do so when the engine is cold. Place your finger over the fitting hole quickly after removing the sensor to minimize the amount of coolant that you will loose, then quickly remove your finger from the hole to install a new sensor. The less antifreeze you loose, the less mess you will have to clean up, and the less antifreeze you will have to add back to your car. Good Luck.............Rooster2