210 Degrees Normal Engine Temperature? Is My Sensor Broken?

[JohnCampbell08]

Hello guys, I am tracking down what I thought to be an overheating problem. I took your advice, and bought a little OBD2 reader, so I now have digital read for engine temp and misc.

After a lot of driving and idling, the car sits at 210 degrees, bounces around from 210-212 but never much more or less.

HOWEVER, the needle jumps around like crazy. The temp reading seems to only move around after the engine is fully warmed, but if I flick the headlights on and off, the needle bounces around like crazy...moves around 1-2hrs on the temp gauge if it was a clock...BUT the temp doesn't actually change in the slightest...from 210-212.

I don't feel like the car is overheating, since the actual temp doesn't move when the needle moves. Does this mean I need to replace my coolant temp sensor or is there another issue at hand?

Thanks for all your help!

[paranoidjack]

Sounds like you're having an electrical issue, which could be 100% unrelated to your temp sensor's condition. Have a buddy watch the needle and jiggle harnesses here and there (once warmed up) and try to find the source of the issue. I had a similar issue but fixed it through fixing other issues which happened to resolve it.

[JohnCampbell08]

That is a good idea. Let me see if I can get someone to lend a hand tomorrow morning.

My initial idea was that it was a bad ground or something somewhere...so that when the headlights came on and off, the electrical load would make it fluctuate, but have no idea where to start.

Is 210 a good consistent number to be at? That is the needle right at half, or a little behind half towards cold....so it looks right. Just when the headlights turn on or sometimes just letting it sit, it will creep over, but the reading still shows 210-212

[Eskimo91q45]

210 is about what the temp should be based on other cars ive had being around that you could buy i new thermostat that opens at like 190 o something but im pretty sure the temp is right

[willko1]

210 is about what the temp should be based on other cars ive had being around that you could buy i new thermostat that opens at like 190 o something but im pretty sure the temp is right

Replaced my Thermostat on same 2000 y33 last week it is clearly stamped 82 degrees C same as 180 degrees Fahrenheit so temp looks really close. I wonder what temp the auxiliary fans kick in at?

[black g50]

It's possible your starting to run lean,and your head is getting hot.

[maxnix]

Seems like normal is about 195° F.

Have you checked or replaced your thermostat?

[JohnCampbell08]

New thermostat and new radiator caps.

If it was an overheating situation, wouldn't the temp progressively get higher? Not stay at the same temps.

The car runs perfect 95% of the time, but it does misfire sometimes, and will throw a random misfire code. But 95% of the time, it runs smooth as butter, no idle issues, no acceleration issues etc.

[djwarner]

By no ways an expert in these matters, but it appears you may have a pressure leak. First some basics:

Pure water boils at 212 degrees at sealevel. Most modern systems are pressurized to raise the boiling point because the higher the temperature difference to outside air, the better heat transfer occurs through the radiator. (There is also some efficiency increases when the engine runs hotter.)

Pressures are regulated by the radiator caps and are measured in PSI required to open the relief valve. As the coolant warms and expands, pressure increases and the cap opens allowing coolant to flow into the recovery tank. When the engine cools, a vacuum is created and the cap allows coolant to be sucked back from the recovery tank.

When you heat water, the temperature of the water remains at 212 until the water is gone. All the excess energy being added goes into making steam thus the temperature remains stable. Maxim machine guns and some early internal combustion engines were water cooled without the use of radiators by allowing water to boil off, disippating heat.

If you have a pressure leak somewhere in your system, water starts boiling at 212 or so (depending on altitude and gage accuracy).

So the next question is, "are you losing coolant?"

Then, "are you using a 50-50 antifreeze coolant or pure water?" Antifreeze solution also increases the boiling temperature of the solution.

[maxnix]

New thermostat and new radiator caps.

OK, OEM? Did you test them?