Best car radiator temperature sensor?

Suggestions about what to use for a temp. sensor to place into the radiator fins (dry) of a car? I had an LM34 working for 2 days but now I'm getting erronious readings. The signal lead is about 8 ft. long and is un-twisted, and goes through the engine compartment.

I am unclear about the fnction of twisted paired wire leads (remote use), thermistors vs. temp. sensors, volt vs. current signaling. Any proven dirrect method? Repeatability over accuracy is the concern. The range is approx. 180 - 230 deg. F

Thanks,

I use Thermistors over hundreds of metres of cable without problems or noise with tens of thousands of installations in Buildings (Heating & Air Conditioning controllers) in use daily. Chose the right Thermistor for your Temperature range and you'll get better than 1F Resolution. I achieve 0.25C accuracy across -30C to +100C using the PIC's internal 10-bit ADC's.

What range do you intend to cover?

Sorry i missed out the range in your post.
Thermistor is the way to go.
They are not difficult to use. easiest would be to create a lookup table and a bridge network(constant current) with the thermistor forming part of your brigde.
Then use the on board A/D to measure the voltage and index this to your lookup table.


Toni

Thanks for the suggestions. Do I understand it correctly that the current signal is more stable as opposed to a voltage signal, and is appropriate in a harsh, remote environment, such as a car radiator run to the cabin interior?

This link should give you an idea http://www.emesys.com/BS2math3.htm

Toni