Inaccurate temperture reading after replacing sender unit

[johnnyemac]

Hello again,
I recently replaced the temp sending unit after testing the wire to it. When I grounded the wire the gauge did rise to 270, so I figured the wire harness and gauge were ok.
Now that the sending unit has been replaced when I run the car the gauge reads about 140. When I shut the car off the gauge immediately rises to 190 as where I expected the gauge to read. I realize these gauges aren’t very accurate, but this seems a bit odd to me.

I just purchased this car and am positive it has a thermostat in it. That’s next on my list to do, but wanted to ask if anyone had any idea what could be causing this to occur?

Thanks in advance for any suggestions or advice.

 

[Opposedodie]

I had about the same problem with mine, but mine was not jumping up after...
It cost me a set of head gaskets , so I got an after market gauge set and I am now reading the right Temp...my factory gauge is setting at the upper most reading at this time... I wouldn't trust it .... My thurmo stuck closed and it was reading about 140 ....

 

[Beasty306GT]

go with aftermarket gauge..stock ones are useless

 

[87_LX_5.0]

For all the hassle involved with chasing problems on a gauge that is never going to read or work correctly you will thank yourself later for spending $60-$75 on a good aftermarket tempature gauge.