 Oil temp sender going bad? |
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| jvmarino |
 Oct 11 2023, 08:41 AM
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#1
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Member  Group: Members Posts: 80 Joined: 22-March 09 From: Baltimore Member No.: 10,188 Region Association: None  |
Saw a recent post that reminded me of a question I wanted to ask the combined knowledge here.
My oil temp sender has been acting wonky the last few years, and I have assumed it was a failing sender, but wanted to see if others agree. Car is a 74 model that gets about 1k miles a year on it. It is likely the original sender and starting about a year ago, if the engine was cold, the gauge would peg full temp when first running the car. After it warms up (about 10 minutes), the gauge then reads normal. I have assumed that the thermocouple inside the sender is open circuiting when it is cold and then reconnects when it gets a bit warm. Is this a typical thing that happens when the sender begins to fail? |
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| dr914@autoatlanta.com |
Oct 11 2023, 09:13 AM
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#2
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914 Guru Group: Members Posts: 7,857 Joined: 3-January 07 From: atlanta georgia Member No.: 7,418 Region Association: None |
I would first check the wire between the sending unit and the main harness in front of the battery, the lead often gets brittle and grounds causing the needle to peg
QUOTE(jvmarino @ Oct 11 2023, 07:41 AM)  Saw a recent post that reminded me of a question I wanted to ask the combined knowledge here. My oil temp sender has been acting wonky the last few years, and I have assumed it was a failing sender, but wanted to see if others agree. Car is a 74 model that gets about 1k miles a year on it. It is likely the original sender and starting about a year ago, if the engine was cold, the gauge would peg full temp when first running the car. After it warms up (about 10 minutes), the gauge then reads normal. I have assumed that the thermocouple inside the sender is open circuiting when it is cold and then reconnects when it gets a bit warm. Is this a typical thing that happens when the sender begins to fail? |
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| 914Sixer |
Oct 11 2023, 09:18 AM
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#3
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914 Guru Group: Members Posts: 8,882 Joined: 17-January 05 From: San Angelo Texas Member No.: 3,457 Region Association: Southwest Region 
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Here you go, one of Jeff Bowlsby harness $33
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| jvmarino |
Oct 11 2023, 10:11 AM
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#4
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Member Group: Members Posts: 80 Joined: 22-March 09 From: Baltimore Member No.: 10,188 Region Association: None |
Thanks for the responses. I did try to quickly check the cable by fiddling with it to see if the reading changed, but can inspect it more thoroughly next time I am under the car.
If I understand what I have read here on the forums, the gauge will peg when circuit is both shorted or open. Is this correct? |
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| Dave_Darling |
Oct 11 2023, 12:33 PM
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#5
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914 Idiot Group: Members Posts: 14,986 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California
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I think it will stay at the bottom if open circuit and peg to the top if shorted to ground.
--DD |
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| jvmarino |
Oct 11 2023, 06:50 PM
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#6
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Member Group: Members Posts: 80 Joined: 22-March 09 From: Baltimore Member No.: 10,188 Region Association: None |
Well if that is the case, it will make it much easier to troubleshoot.
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