Is it ok to install a temperature sending unit with Blue Monster Teflon tape , or should it be installed without any sealer or tape ? On my re-built engine I installed a new " Stant " made in Mexico temperature sending unit , and once the gauge started to rise it would climb to hot . Using a laser heat gun on the upper , and the lower radiator hoses they each read 138*, and the short heater hose was 174* the heater hose to the intake was at 190* , heater to water pump was at 190* You could take the radiator cap off and see no signs of overheating . Today I reinstalled the old original AC temp sending unit , again using 2 wraps of the Blue Monter tape , and after running for 5 minutes the temp was at the middle range of the gauge , and then slowly after another 5 minutes running again went towards hot . On an ad from Tracy Corvette they sell a re-pro A/C sending unit , and say not to use any sealer on the threads ? The ad says this sending unit may not be calibrated correctly " For re-built or original gauges " , and that you can use part- MSG US - resistor to correct the gauge reading . My car has the front clip off the car with no inner fenders , outer fenders , hood etc. . I removed the tape from the original sending unit , and it did not make any difference , it was still not accurate .