How to fix a temp gauge?
Thread Starter
Racer
Joined: Jun 2004
Posts: 376
Likes: 0
From: Va
How to fix a temp gauge?
Hello from the new guy. Been reading your forum for a month now and enjoy every minute of it. Love all the pictures and info, hopefully I can contribute to some of the questions. Picked up my first Corvette back in March, a ‘71 coupe, 4spd, (how do I attach a picture?) The car is mostly original and I would like to keep it that way. As it is mostly original, it has all the problems of a 33 year-old car. Engine, frame, suspension, AC, rear bearings, temp gauge, clock and ammeter all need attention. The good news is that it is driveable and I plan to do a little at a time while keeping it on the road. I have a hundred questions, but I’ll give you one at a time. On initial start up, the temp gauge sits pegged for about 15 minutes, then starts to slowly move. After 30 minutes the gauge reads about 120. The gauge moves, however, it reads way low. Where do I start troubleshooting? Thanks for all the help,
Oscar
Oscar
Melting Slicks
Joined: Oct 2002
Posts: 3,255
Likes: 0
From: Manalapan FL
Re: How to fix a temp gauge? (raider21)
I've got a temp guage with a mind of it's own, too. Have you replaced the sending unit? Apparently, Lectric Limited (or is it Painless?) makes a "correct" sending unit which works with vintage guages. That is the easiest/cheapest place to start.
Do not use teflon tape or sealant on the threads when installing the sending unit. The sender must be grounded to the block.
If that doesn't work, replace the guage with a correct unit. Some NOS/OEM guages are available thru the Corvette Catalogs in the $50 range.
I've given up on mine. I'm just gonna install a new mechanical guage and be done with the frustrating guessing game.
D. Ocean
Miami, FLA
Do not use teflon tape or sealant on the threads when installing the sending unit. The sender must be grounded to the block.
If that doesn't work, replace the guage with a correct unit. Some NOS/OEM guages are available thru the Corvette Catalogs in the $50 range.
I've given up on mine. I'm just gonna install a new mechanical guage and be done with the frustrating guessing game.
D. Ocean
Miami, FLA
Safety Car
Joined: Jul 2002
Posts: 4,269
Likes: 3
From: St. Charles IL
Cruise-In 5-6-7-8-9-11-12 Veteran
A CI-6 Car Show Winner
Re: How to fix a temp gauge? (raider21)
I completely agree with 74FLCONV. Try the Lectric Limited sender first, if you still have problems contact Jason at: (e-mail) vetteinstruments.com (there is no website) He calibrated my gauge to the Lectric Limited sender, works like a charm.
[Modified by Big Fish, 10:34 PM 7/6/2004]
[Modified by Big Fish, 10:34 PM 7/6/2004]
"Rodstoration &am p;quot; In Progres
Joined: Jun 2004
Posts: 1,397
Likes: 1
From: Frisco TX
Re: How to fix a temp gauge? (raider21)
It took me a while to figure out the picture thing also.. but with the help of some new friends on the forum I've finally got it down. Try uploading your photo(s) to photobucket.com (will need to set up a free account). Then just copy and paste the image url from below the picture into your post text here.
Works great.
Ed
Works great.
Ed
Drifting
Joined: Nov 2003
Posts: 1,634
Likes: 4
From: Northern NJ
St. Jude Donor '04 & '05
Re: How to fix a temp gauge? (raider21)
Welcome to the insanity! 
To post pics, you have to upload your pic(s) to a location on the internet and then in your post, click on the image tag button and place the whole address to the pics between the image tags. It should look something like this.
(note the image tags are misspelled so they will show up here and not
actually try and display a picture)
[IMAGE]http://www.yourdomain.com/pictures/yourcarpic.jpg[/IMAGE]
Hope this helps. Good Luck!
To post pics, you have to upload your pic(s) to a location on the internet and then in your post, click on the image tag button and place the whole address to the pics between the image tags. It should look something like this.
(note the image tags are misspelled so they will show up here and not
actually try and display a picture)
[IMAGE]http://www.yourdomain.com/pictures/yourcarpic.jpg[/IMAGE]
Hope this helps. Good Luck!
Melting Slicks
Joined: May 2001
Posts: 2,131
Likes: 4
From: May help you? You can sure as hell try!
Re: How to fix a temp gauge? (74FLCONV)
Lectric Limited also has a web page describing how to trouble shoot your temp gauge system. There is also a resistor that is installed across the terminals of the gauge that may be missing that you may want to check for.
I used the Lectric Limited sender and the temp readings fell right in line. Even the replacement Delco sending units (which is what I was using before) give false readings. Want to buy one cheap?
Melting Slicks
Joined: Jul 1999
Posts: 3,030
Likes: 17
From: White Pine / Dandridge TN
Re: How to fix a temp gauge? (LemansBlue68)
Welcome. I had the same problem when I bought my vette. It had the wrong sending unit installed. I purchased an AC Delco unit and have had no problems ever since. A good tip previously mentioned is about the teflon tape. You can use a little...not to much or the it wont ground properly. I found out the hard way when I used to much. Also, as mentioned, you need the resistor that sits on the terminals behind the instrument itself. I don't know if you can buy them in the aftermarket but if it is missing you can probably find one from a vette junkyard.
Melting Slicks
Joined: Aug 2003
Posts: 2,135
Likes: 2
From: Dayton Oh
Re: How to fix a temp gauge? (raider21)
Although I agree with everyone above, try cleaning the connection at the sending unit before replacing it. Make sure the sending unit terminal and the wire terminal are clean and bright. Might save you a few bucks and worth the little effort required. Good luck and welcome from me too. 
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