I don't think they went to electric temp guages until 56, so my guess
is that your truck was converted at some time.
Check the wire between the guage and the sensor. Guess is that it
is broken and/or shorting somewhere. Could also be a combination
of a grounded sensor wire and an intermittent power supply problem
to the guage.
Also, did you use thread sealer on the new sender? You shouldn't
have. The circuit runs 12V to guage, guage to sensor, sensor to
ground. The sensor resistance varies with temperature, about 30
ohms cold and near 0 at full scale hot.
Lift the wire at the sensor, guage should show cold. Ground the
wire, guage should show full hot. Ground the wire through a 15 ohm
resistor (from Radio Shack) or a ballast resistor, and it should
read somewhere in the middle.
Sensor should measure near 30 ohms at cold and near 15 ohms at operating
temperature from the terminal on the top to engine ground.
Bruce Kettunen
57 3200
Mt. Iron, MN
At Wednesday, 12 November 2003, you wrote:
>Hi I have a problem that maybe someone here can help me with.I have
a 235
>engine . My engine temp gauge goes fro cold to hot after about 10
minutes . It
>doesnt gradualy do this . It jumps to hot and nowhere in between.
The radiator
>is full. Ive replaced the thermostat and sending unit and I dont
think its the
>waterpump. The radiator doesnt overheat or overflow . Im wondering
if it could
>have a bad guage because it reads hot all the way or cold all the
way and not
>in betwwen . You would think if the guage was shot it woul not read
hot . When
>you shut the engine off it reads cold after it starts again and
then in a few
>minutes or more -goes directly to hot Any ideas or suggestions
? Anyone else
>have this problem ? Thanks again Mark
>oletrucks is devoted to Chevy and GM trucks built between 1941 and 1959
>
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