As the title says, the gauge needle goes up to the red when moving, comes back down to right about halfway when idling. My radiator thermometer says the water at the radiator is not hot, no pressure no steam when the cap is removed. Shop said it was a clogged radiator, so I replaced it and the thermostat and hoses, no change. Could it be as simple as the sensor? Where is it?

 

I am guessing it could be a coupe of possibilities (or more)
One is the water pump is not working as efficiently when moving vs idling??
The other is that the dial indicator is following the alternator output at higher rev (moving)
Of course, it could be the sensor is faulty.

I am thinking if you get a manual (even a Haynes manual) then you would have more information to test the part before spending the money to replace it

Good luck

 

Thanks for the response.

I did buy a Haynes manual, and I have Googled and searched, and I cannot find the location of the ECT sensor. I found what I thought was it neat the thermostat housing, but it doesn't even resemble what NAPA sold me as the ECT, and I just don't want to start yanking parts I can't confirm what they are.

I changed the thermostat and when there was no change I put it in the shop, which said it was the radiator, they wanted $700 to do the radiator - it is a $200 part, so I did it myself.

If it is a gauge problem, I am not equipped to test that. I am also not changing the water pump, but a $20 sensor is in my mind, worth a shot before I take it to another shop.

 

My Haynes manual for my '01 Elantra clearly has it listed in the index in the back of the book.
Then, looking in the pages, there are pictures showing the location
I don't understand why your manual would be so different

Anyway, I always thought the ECT should be near the crankshaft position sensor
Try looking at the ignition coils connector
Underneath it is a sensor, maybe that is the ECT??