62 Temp Guage
Thread Starter
Drifting
Joined: Apr 2004
Posts: 1,306
Likes: 36
From: Allen Park Mi
62 Temp Guage
Reading way hot.
just put a new sending unit in from
Lectric Limited and its just as off as the old one
reading 240 when its at 180
Is there a resisitor in the gauge thats opened up and can be replaced?
just put a new sending unit in from
Lectric Limited and its just as off as the old one
reading 240 when its at 180
Is there a resisitor in the gauge thats opened up and can be replaced?
Burning Brakes
Joined: Jul 2014
Posts: 1,206
Likes: 378
From: Knoxville, TN
2020 C1 of the Year Finalist - Unmodified
You're lucky. At least your temp gauge reads something. I just installed a new Lectric Limited sending unit and my temp gauge still shows dead cold.
Melting Slicks
Joined: Jul 2004
Posts: 2,869
Likes: 196
From: Maryland
Calibrated temp Senders of that time period are very hard to find. If tou have an understanding auto parts store (liberal return policy) you could buy a dozen TU5 senders to find one that works.My temp gauge with the original sender on my 62 reads 135 ohms@ 180 *. Heat some water to 180* and measure the resistance of the sender while in the heated water to find one that works.
Safety Car
Joined: Dec 1999
Posts: 4,402
Likes: 1,192
From: Lexington,NC,USA
C1 of Year Finalist (track prepared) 2019
I had a similar problem with our '62. I tried placing a rheostat in the wire from the temp sender to the gauge and adjusted it so that the gauge would read correctly at 180°, but it was not very accurate at other temps. I took an ohm meter to the local Oreilly's and measured all the temp sensors that were supposed to be for this vintage Corvette, but none of them had the correct resistance at room temp. I purchased the one closest to the proper resistance,but it was not accurate throughout the entire range. I finally decided to replace the gauge and sender with an Autometer setup. www.carols62.com/temp_gauge.htm
Race Director
Joined: Feb 2007
Posts: 15,479
Likes: 8,957
From: northern california
C2 of Year Finalist (track prepared) 2019
What you've described is consistent with the sender experiencing self-heating. That is to say that as the sender becomes warmer, the resistance decreases which causes more current to flow which causes the sender to get even warmer which causes the resistance to decrease further which causes more current to flow...... rinse and repeat until the sender causes the gauge to peg to the right (or nearly so).
This is a particular problem for modern replacement senders which do not have a good thermal bond between the internal thermistor and the sender case. Original senders have an excellent thermal bond and are not subject to this self heating in any measurable way.
Here is a link to a thread I started in which I discuss this self-heating phenomenon:
temp sender self heating - click here
