1967 water temp issue

[Wayne C.]

My water temperature gauge isn't functioning properly. The sending unit was replaced first, then the gauge was replaced with an original one that was professionally rebuilt and calibrated. When it was installed, the gauge stuck at 250 degrees. Then on another drive, it jumped back and was operating in the normal range. The next time out, it jumped back to 250 degrees and stayed there. Do you think I have a weak ground or faulty wiring? Any thoughts?

[Keith B.]

Re: 1967 water temp issue

If you unplug the wire from the sender the gauge should drop to zero. Touch the wire end to a known ground and it should max out the gauge.

[Wayne C.]

Re: 1967 water temp issue

thank you for your speedy suggestion Keith. I will give that a try!!

Wayne

[Bill L.]

Re: 1967 water temp issue

HI Wayne:

Are all of the following in good shape: 1) The wire insulation running from the sending unit to the gauge - no breaks, splits or repairs 2) The heat insulation (black covering over the sending wire) again no breaks or gaps etc 3) The slip / snap on contacts at both the sending unit on the block and receiver at the gauge -- both clean and corrosion free -- you replaced the sending unit so it should not be suspect (at least theoretically) is it really good / the correct unit?

These are the basics --- my 66 Big Block 390 HP car had the same issues - it ended up being a spliced together sending wire (not a good job to say the least) -- a new wire with perfect continuity (and a correct heat shield sheath) solved the problem ---

Hope this helps

Regards
Bill

[Wayne C.]

Re: 1967 water temp issue

The wire insulation and heat insulation haven't been replaced as of yet. I believe the contacts at the sending unit and gauge are secure and clean. Replacing the wiring would be another good possibility. Thanks Bill. it's a small block, 327, 350hp '67.

[Bill L.]

Re: 1967 water temp issue

Should be similar for most cars --- the basics first in all cases --- the sending wire and contacts are always suspect ---

As indicated I had the problem on a 66 BB 390HP car --- I have a 67 300hp car now --- same set up but no issues ---

[Joe L.]

Re: 1967 water temp issue

My water temperature gauge isn't functioning properly. The sending unit was replaced first, then the gauge was replaced with an original one that was professionally rebuilt and calibrated. When it was installed, the gauge stuck at 250 degrees. Then on another drive, it jumped back and was operating in the normal range. The next time out, it jumped back to 250 degrees and stayed there. Do you think I have a weak ground or faulty wiring? Any thoughts?

Wayne------


Did you use sealer on the threads of the temperature sender?

[Wayne C.]

Re: 1967 water temp issue

Hello Joe,
Yes, the threads were sealed on the sender.

[Leif A.]

Re: 1967 water temp issue

Hello Joe,
Yes, the threads were sealed on the sender.

That could be contributing to your issue. Thread sealer is not necessary and, by most, not recommended. Threads on the sending unit need to make a good contact with the intake manifold.

[Michael W.]

Re: 1967 water temp issue

If the thread compound was affecting the indication the gauge would read low, not high. Sounds like a stuck gauge.

[Leif A.]

Re: 1967 water temp issue

If the thread compound was affecting the indication the gauge would read low, not high. Sounds like a stuck gauge.

True, Michael, but wouldn't you agree that the tape could possibly affect his reading? And, that it is unnecessary??

[Joe L.]

Re: 1967 water temp issue

Hello Joe,
Yes, the threads were sealed on the sender.

Wayne-------


Try removing every last bit of the sealer from the manifold and the sender. Once-upon-a-time I had a problem very much like you describe after I re-installed a sender with the threads sealed with Teflon tape. I just couldn't figure out what was wrong. Finally, I decided that maybe it was the tape sealer, so I removed all of the tape. That completely cured my problem.

In any event, removing the sealer will not be in any way detrimental. You don't need it. The threads for the sender are "Dryseal" and require no sealer of any kind.

[Wayne C.]

Re: 1967 water temp issue

We tried to isolate the problem by disconnecting the green wire to the sending unit and running power directly to the back of the gauge. The gauge still shows pegged at 250. After a phone call to the gauge rebuilder, he thinks there is a direct short at the cluster. We are double checking the connections to see if that's the problem. Considering the gauge worked for a short ride, then jumped up to 250, it's possible the connections are just barely touching off and on causing the malfunction. I will keep all posted. Thank you for all your suggestions!

[Stephen L.]

Re: 1967 water temp issue

I assume you have recently installed this rebuilt gauge, sooooooooooooooooooo........
Your problem could be an incorrect installation of the gauge in the mounting plate or an incorrect ground of the cluster. I've included a photo of the back of the cluster. Note the position of the tan phenolic insulator. It must be installed in this orientation. Also insure that the screws that hold the gauge mounting plate are tight and no corrosion. Lastly, insure that you have a good ground for the cluster.

[Wayne C.]

Re: 1967 water temp issue

Hello all, the problem has been resolved! The gauge was shorting out in the instrument cluster. All four nuts were loosened and then the gauge was 'tweaked' slightly in the panel, then the needle dropped down under 100. The nuts were tightened and all is well. The gauge now reads in the normal temperature range. The clearance tolerance must be very critical. Thank you to all posters who helped. Regards, Wayne