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Electrical Temp gauge not reading correctly

  • Thread starter Thread starter craig3x
  • Start date Start date Dec 10, 2012
C

craig3x

New Member
Dec 8, 2012
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Dec 10, 2012
#1
  • Dec 10, 2012
  • #1
the temp gauge on my '65 is reading hot, but I had a laser temp of the engine done and it's reading 178 degrees. Any ideas why it's reading incorrectly? Could it be an old brittle wire? Does resistance make it read hotter?
 

bartl

Active Member
Feb 4, 2001
218
8
29
West Rutland, Vermont
Dec 11, 2012
#2
  • Dec 11, 2012
  • #2
The opposite. The more resistance, the LOWER the gauge reads. Sounds like a bad sending unit.
 

Jake2012

Member
Jul 26, 2012
35
1
9
Dec 11, 2012
#3
  • Dec 11, 2012
  • #3
Agree with Bartl , I'm no autoelect but from experience most faulty temp gauge reads are caused by a faulty sender unit. Suggestion, not sure if you can test output of the temp sender unit ? If not, try changing the sender unit b4 doing other fault testing.
 

tx65coupe

Active Member
Nov 29, 1999
1,551
1
37
Jan 1, 2013
#4
  • Jan 1, 2013
  • #4
What about the fuel gauge? It could be the instrument cluster voltage regulator. I have an electronic solid state one now. The only mechanical one I have had that works close to right is the original one.
 
2

2+2GT

10 Year Member
Apr 25, 2009
3,333
10
79
Southeastern Pennsylvania
Jan 1, 2013
#5
  • Jan 1, 2013
  • #5
Jake2012 said:
Agree with Bartl , I'm no autoelect but from experience most faulty temp gauge reads are caused by a faulty sender unit. Suggestion, not sure if you can test output of the temp sender unit ? If not, try changing the sender unit b4 doing other fault testing.
Click to expand...
I agree. A couple years ago, I tested replacement senders from every manufacturer. Standard, Echlin, Delco, you name it. Ω was tested at 100°F. They all sucked, not even close. If you don't have an original Autolite or Motorcraft replacement, get one. They aren't available new, so you'll have to find one.
 

bartl

Active Member
Feb 4, 2001
218
8
29
West Rutland, Vermont
Jan 24, 2013
#6
  • Jan 24, 2013
  • #6
2+2GT said:
I agree. A couple years ago, I tested replacement senders from every manufacturer. Standard, Echlin, Delco, you name it. Ω was tested at 100°F. They all sucked, not even close. If you don't have an original Autolite or Motorcraft replacement, get one. They aren't available new, so you'll have to find one.
Click to expand...

The only other option is to find a resistor with the proper value to "calibrate" the gauge.
 
C

craig3x

New Member
Dec 8, 2012
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Jan 25, 2013
#7
  • Jan 25, 2013
  • #7
hmmm, I bought the car a few months ago, and it has a new intake on it and the sender looks to be new as well. My fuel gauge is accurate as far as I can tell, so I don't think its a cluster problem. Not sure what to do if all the aftermarket senders are crap as 2+2GT says
 
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