C2 Temperature Sender

[Ralph E.]

Need some advise. When installing reinstalling my temperature sender on my 327/300Hp Cast Iron manifold should I use a thread sealer?

[Joe L.]

Re: C2 Temperature Sender

Ralph-----

Absolutely not. The sender must ground through contact with the manifold. Using any sort of sealer or Teflon tape can interfere with the grounding and cause erratic/erroneous readings. If you must use sealer, then use a q-tip to apply it to just the bottom few threads in the manifold. Then, install the sender and torque to spec.

[Ralph E.]

Re: C2 Temperature Sender

Thank you very much I'm sure this must have been posted before but I couldn't find it.

[Wayne W.]

Re: C2 Temperature Sender

It funny everyone thinks that sealer will cause grouding problems and almost every sensor that you buy from the General and other vendors these days has it already pre-applied on the threads. We are dealing with pipe thread here and by nature it will bite into the piece that it is screwed into. Thus the electrical connection will be very effective with or without sealer. I challenge anyone that has very sensitive measuring equipment to test this. You will find that with a well tightened fitting the difference in resistance will be negligible.

[Joe L.]

Re: C2 Temperature Sender

Wayne-----

I have personally experienced problems with the senders when sealer was used. Many years ago when I was a novice, I installed a sender using teflon tape. It didn't work properly so I figured I had gotten a "bad" sender. I got another and installed it with teflon tape. It didn't work properly, either. Someone asked me if I had used sealer and I, of course, affirmed that I had. I removed the sender, thoroughly cleaned off the sealer and re-installed it. It then worked perfectly.

I've not seen a GM sender with pre-applied sealant. The 56-79 senders I've seen, NOS or the current SERVICE replacement, have no sealer pre-applied. Other GM senders may, though. However, if any of these senders are 2 terminal units, then they don't ground through the threads so sealer won't interfere with anything. Also, GM may apply sealant to the threads in such a manner that some threads are left exposed. In fact, that could be why the sealer is pre-applied rather than allowed to be field-applied.

[Jack H.]

Echo....

Joe's comments regarding NOS temp senders with pre-applied thread sealer. I had one NOS AC 1513321 in original old 'blue box'--no thread sealer pre-applied. I'm holding an NOS 12334869 temp sender (Made In USA version--red, white & blue box) in my hands--no thread sealer pre-applied. So that's a whooping sample size of TWO whole units! I've also not seen a reference in service books calling for thread sealer when doing R&R of temp sender or temp switch components....

On Wayne's side though, a light application of liquid thread sealer WILL typically 'spread' on temp sender installation and give sufficient metal-metal surface contact to properly ground (and Joe echoed this--small/light coating). On Joe's side, I too have seen more than one car in the shop using teflon tape where removal of the tape DID alter temp guage reading.