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Posted by: jvmarino Oct 11 2023, 08:41 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?

Posted by: dr914@autoatlanta.com Oct 11 2023, 09:13 AM

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?

Posted by: 914Sixer Oct 11 2023, 09:18 AM

Here you go, one of Jeff Bowlsby harness $33

Attached image(s)

Posted by: jvmarino Oct 11 2023, 10:11 AM

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?

Posted by: Dave_Darling Oct 11 2023, 12:33 PM

I think it will stay at the bottom if open circuit and peg to the top if shorted to ground.

--DD

Posted by: jvmarino Oct 11 2023, 06:50 PM

Well if that is the case, it will make it much easier to troubleshoot.

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