Join Date: Mar 2002
Location: Austin, TX, USA
Re: Driving=temperature up | Idle=Temp down
Also, check for bad connections. Use a volt meter and measure accross various connections in both the hot and ground circuits. For example, measure negative cable to engine block, negative cable to frame, positive cable to guage power. You should see less than a few hundredths of a volt drop at each point.
If you have a bad connection, charging currents can throw the ground voltage off (for example) and make the meter misread. The temp guage uses the engine block for the sensor ground and the body for guage ground. If these two grounds aren't within a few millivolts of one another, the guage will misread.
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI