Don't troubleshoot based on assumptions. It's the easiest way to go running down the wrong path. As yet you do not know whether the temperature signal reading is correct on the car is running too cold or if the temperature is in fact higher and the sensor is reading low. Check this up radiator hose after the vehicle is warmed up. If it gets warm immediately after startup, your thermostat is likely stuck it's partially open.

You did not answer the question of where your temperature gauge needle reeds when the vehicle is warmed up. This is a surprisingly useful piece of information for these cars. Not trying to correlate needle position with an exact temperature, but it can be correlated with temperature range.

 

Sorry for the long delay, had a death in the family that derailed me. I did some testing and I think the thermostat spring is weak and opening early. According to my parents (original owners) it's the original thermostat.

 

Condolences for your loss.

You still don't know if the thermostat is misbehaving or the temperature sensor is misbehaving.

Please remove the squeeze connector on the ECTS with the engine ice cold and measure the resistance. Do the same with the car at idle once warned up. Post the actual outside temperature for a cold engine temp sensor reading, and also the needle position on the gauge when warmed up.

You can guess at The thermostat behavior which you can't see, or guess that the ECTS is not reading correctly, or you can take some actual measurements and we can work from there.

 

Sorry I wasn't clear, I started the car, and monitored the temp of the upper radiator hose, and it started to heat up earlier than it should have. The temp gauge wasn't up to the hash mark when the water started flowing. I would much rather it was the temp sensor, it's easier to get to. Honestly if I have to drain the coolant I'll probably just change them both as they're both cheap parts.

 

There's coolant in the block, not circulating, with the stat closed. Some of that heat is transferred throughout the cooling system due to the high thermal conductivity of coolant.

But whatever. You're going to do whatever you're going to do, so I'll stop trying to impose logical troubleshooting on you.

 

Just to point out, you were the one who suggested gauging the temp by the top radiator line, but whatever, just be rude.

 

Damn straight I did.

As a yes no is there flow check.

But to your point, still in general hypocritical.

Your scan tool will determine the temperature by inferring the resistance of the ECTS which changes with temperature. If your ECTS is reading incorrectly, your scan tool will display an incorrect temperature.

Then, you need to keep in mind that due to the location of the ECTS in the head, you shouldn't expect it to be reading the same temperature as you would expect the thermostat to be at. They are at different points physically in the cooling system. So to assume they are showing a 20° difference may in fact be exactly what you should expect to see. Is it? I haven't the slightest idea and I'm not in the mood to pull out my fluid thermodynamics textbooks from grad school. If you want to know if your thermostat is bad, pull it, clean it without touching it, the spring part, and boil it in a pot of water on the stove with a thermometer or IR gun to measure the temperature. The temperature it is labeled with is the temperature at which it should begin to open. Not be fully open. Do not buy an AC Delco professional replacement. They are made by Moto rad and are known to be pieces of ****e. Put one in one of my Saturns, tested it in the garage, began to overheat three times in a row after cycling properly twice. Just stuck closed. They get crap reviews across the internet so it is not just my lack of skills which are indeed suspect.

I reserve the right to be straightforward when I spend a significant amount of time trying to help people solve their problems but for whatever reason, the people that come here sometimes ask for assistance but then don't follow the suggestions they are given to diagnose the problem.

And for some reason, it always seems that these same people respond immediately to my straightforward communications while continuing to ignore the suggestions from myself and others.

I like putting Saturn's back on the road and keeping them there.
Everyone who posts questions on this site shares that desire whether it is for their Saturn or someone else's.
All I can do is try.

I've been moderating this site for something like 18 years.
Does that make me special? No. Hell no.
What it makes me is obscenely tired of people asking for help and then not even trying to follow our suggestions.

After 18 years, I still guess at some of the questions for the s cars. Been driving them since 92. Don't know everything and never will. But I have a damn good idea what the deal is.

It's fine for people to post their theories as to what the cause may be. But if you're going to do that before following any suggestions you've been given, why are you here?

Food for thought.