Temp Gauge sender issues

[scguy]

My full HO cluster temp gauge never reads correctly, always high. If I unplug it, it sweeps all the way in one direction, ground it and it sweeps the other way. That should mean the gauge is fine. 

 

My problem is that it always reads high. Like reading 240F within 2 mins of a 40F cold start. Verified with an IR thermometer that it's reading much higher than the head. 

 

Simple fix, right? I installed a new temp sender (Standard brand). Same problem. I did use Teflon tape on the threads. Am I not supposed to seal the threads to allow it to ground better?  I plan on grabbing an OE one next time I'm at a junkyard, but has anyone had this problem?

[gogmorgo]

The Teflon tape doesn’t make a seal, the tapered threads do. The Teflon tape is just a lubricant to help you crank it down. In this case though you’re correct that you don’t want it in there, because it does affect the sensor’s connection to ground.

 

It would be helpful to know what the part number is for the temp sender you got so someone who knows more than I do can confirm it’s the correct one.