C1 TEMP SENDING INSTALLATION

[Joe D.]

When installing the temperature sending unit should I use teflon tape? Thanks, Joe DeLuca Member#37862

[Mike M.]

Re: C1 TEMP SENDING INSTALLATION

Teflon is a good idea but if you use teflon tape and the judges pick its presence up, there will be a deduction. I use loctite liquid teflon Part # 59321. Its formal name is LOCTITE 592 thread sealant with teflon. even if you use too much, its very easy to loose excess after the sender is installed in the manifold. simply wipe it away with a paper towel followed by a dry paint brush. Judges won't know the difference and it really seals well. mike

[Ed Jennings]

Re: C1 TEMP SENDING INSTALLATION

Some folks have had difficulty with their temp senders when they used too much sealant or teflon. The sealer can interfere with the electrical conductivity between the sender and the manifold. Use sealer sparingly.

[Jack H.]

Chevy Manuals Advise No....

Service books say NOT to use any form of thread sealant when replacing temp senders. Contact with the cylinder head and/or intake manifold provides electrical ground for the temp gauge system and thread sealant (especially teflon tape in the right qty/position) can interfere.... Sender is soft brass who's thread is designed to 'compress' on torque-down and form a no-leak seal all by itself.

[Ed Jennings]

Re: Chevy Manuals Advise No....

Jack, I agree 100% with that. Only problem is with old manifolds, especially aluminum ones. I think sometimes there is a little wear in the manifold thread and and the sender just doesn't want to seal. Also there is a little reluctance to really torque down on an aluminum manifold for fear of breaking something. I would only use sealer as a last resort, and only sparingly then. The manifold on my 62 FI wanted to seep a little after tightening and it scared me to death to tighten the sender much more, but another 1/8 turn finally got it. It hasn't leaked for several years, so I guess it's ok.

[Joe L.]

Re: C1 TEMP SENDING INSTALLATION

Joe-----

I agree with the other responders; thread sealer of any kind can cause problems with temp sender performance. I often wonder if this is the genesis of a lot of the problems that folks seem to have with temp sender "calibration". Anyway, here's what I do:

Using a Q-Tip swab, apply a small amount of sealer to the BOTTOM few threads in the manifold or cylinder head (depending, of course, on where the temp sender is mounted). This provides enough sealer to prevent any leaks and keeps most of the thread contact area free from sealer. You must apply the sealer to the BOTTOM few threads IN THE MANIFOLD OR CYLINDER HEAD and NOT to the last few threads of the sender, itself.

I recommend Permatex Pipe Joint Sealer with Teflon (GM #12346004).

[William C.]

Re: C1 TEMP SENDING INSTALLATION *NM*

[Mike M.]

Re: C1 TEMP SENDING INSTALLATION

agree with just teflon to lower few threads But as i recall, i usually coat the sending unit, tighten it securely, then wipe away any residual. I've done this with about 6 cars i've PV'd successfully. Maybe electrons can swim in teflon -just kidding. mike

[John M.]

Re: C1 TEMP SENDING INSTALLATION

While I agree with the premiss that visible sealant will cause a deduct in judging, I cannot believe that thread sealant would cause a grounding problem.
This is a tapered pipe thread, and the interference fit of the threads will displace all the sealant at all areas texcept where there in a small imperfection. I know that the soft brass will probably seal completely into the iron manifold, but it is better not to chance it. We use teflon dope on fire sprinkler pipe joints in high-rise buildings and the systems are often used as a grounding path for electrical systems. I have tested many sprinkler systems and hve never found one that had greater than a .15 ohm resistance. Keep in mind, that this is on a system that may have to pass through several hundred joints on the way to ground! I would guess that you are more likley to get a worse connection on the negative battery terminal.

Regards, John McGraw

[Mike M.]

Re: C1 TEMP SENDING INSTALLATION

perhaps one of us old flatus generaters ought to get off our butts, pull an alum intake and ac delco temp sending unit and teflon paste and an ohm meter and see just what kind of resistance values we get with teflon. should have thought of this when i posted my previuos responses but its too late in the evening to experiment. maybe one of the young bucks can run the experiment and get back to us in the A.M. mike

[Joe L.]

Re: C1 TEMP SENDING INSTALLATION

John-----

The way that I learned about this situation was the hard way. Many years ago, I installed a temp sender with Teflon tape and the gauge did not work properly. I figured that I got a "bad sender", so I got another one. Same problem. Then, I figured that I had a bad gauge so I got another one. I still had the same problem. I was pulling my hair out. Finally, the thought occurred to me that, maybe, the the teflon tape was behind it. So, I removed the tape with a wire brush and re-installed it "clean". That ended the problem.

[John M.]

Re: C1 TEMP SENDING INSTALLATION

Joe,
I would tend to agree with you on the tape. I have never used tape, I have allways used a paste type pipe dope. I could see that with a couple of wraps of the tape and you would need to really crank down on the sensor to get metal-to-metal contact.

Regards, John McGraw

[John H.]

Re: C1 TEMP SENDING INSTALLATION

It's interesting to note on the original Chevrolet manifold drawings of the era that those female threads aren't referred to as "NPT" (National Pipe Thread) as we do today - they're called out as 1/2-14 "Dryseal", and no sealer was specified on the engine assembly drawings for the sending unit (of course, they weren't too concerned about galvanic corrosion or someone trying to remove one 50 years later)

[Joe L.]

Re: C1 TEMP SENDING INSTALLATION

John-----

The pipe thread compound might be less of a problem than the Teflon tape. But, the way I figure it is this: if one applies the sealer the way I described earlier one achieves 3 things:

1) threads adequately sealed against any possibility of leakage;

2) no uncertainty, at all, regarding grounding; grounding is assured through the thread interface with no sealer applied;

3) no sealer "squeeze out" requiring removal or for judges to see.

All of the above for the price of a Q-Tip (about 5 cents). You'll never get a deal like that on eBay.