I had a new sending unit installed and tested all leads. Everything is fine. Yet when idling the car sits at around 180, perfectly fine, but when I'm driving it goes down to 150 to 160. Yes, I changed thermostat as well. It has a 180 t state now.

What could this be? The heat gets hot and the defrost works. I may just put an aftermarket gauge in, even though I would rather not.

I know the gauge isn't stuck cause it moves up when idling.

Any help?

 

Oh and it's a 94 Z LT1

 

hook a mechanical gauge to it and see how far off the stock gauge is. 4th gen gauges are known for being off. if you have a temp gun try testing the temps.

 

Factory temp gages are never super accurate when they are new. yours ia almost 20 years old. The main point of the gage is to make sure something is not going wrong, I am not sure the best way to explain it. It is an advanced dummy light. You compare the gage against itself. If the gage is reading low you test the thermostat. If the thermostat is working right your done, you just have a gage that reads a little low. If you have heat I do not see the problem? If your temp was really 160 you would have very weak heat.

 

Yeah I agree the heat would be very weak. But then again if when it says 150 that would mean it is more like 180. So when it goes up to 180 wouldn't that mean it would be more like 210 or so?

 

Don't ever believe the gauge. Get s scanner and look at what the pcm is seeing before doing anything else.

 

The cooling fan does not even come on until the engine gets to 225 or so.

 

I will try that. Thanks for the info. I'm gonna buy an aftermarket gauge as well just to see what it says.

 

you can test what the sensor is seeing using a ohm meter. this is a good site if you have not seen it yet, click how to and click number 12 4th Gen LT1 F-Body Tech Aids

 

Is the auto zone t stat the right one for this car or do I have to order from another site? I know it is supposed to have that metal ring at the bottom that is supposed to seal to the head.