This may sound like a dumb question (and it probably is), but out of the four quarter marks on the coolant temperature gauge, what temperature is the one between the 100 and the 220? My car usually doesn't even make it there, that's why I'm wondering. The only time it will is if I'm at a light for a long time or otherwise moving very slow. That's with neither of the radiator fans turned on too. I have a 165 tstat. Yes, 165, not 160.

 

Midway between 100 and 220 is 160.

 

The gauge is not linear, so it's not strictly accurate to just divide that range in half like that.

As you will notice, the low end is 100; the middle is 220, i.e. it takes 120° to go the 1st half of the gauge; but the high end is 260, meaning it only takes 40° to go the other half.

The sensor is DEFINITELY not linear. It's more of a log curve. But the gauge itself isn't linear either. (speaking strictly as a mathematician) I don't think it's realistic to even try to calculate a transfer function for the whole system.

Although I've never measured it, I'd estimate the "¼" mark at closer to 175°.

 

When it gets to that point hit your thermostat with a infrared thermometer. You'll know for sure that way.

 

Okay, thanks guys. And yeah, I noticed the differences too and that's why I didn't think it was linear. Is it normal to only be about halfway between 100 and that mark though when running a 165 tstat? It just seems a little cold to me, and it seems like it's cooling below 165 judging from how far away it is from the ~175 mark (assuming that's what it is, but theoretically it makes sense).

 

As mentioned ,the only way to know how hot or cold your car is actually running is with a Inferred laser temperature gun.


Compare the reading from the Thermostat housing to the gage to see how far off it is.


= http://www.harborfreight.com/catalog...ed+Thermometer


Or a shop can do it usually for free. Its a 30 second job.

 

My car with a 180* thermostat sits just above the first mark, so Sofa may be correct-or-close...

 

Okay, in that case my car probably runs far too cold even for a 165* thermostat




That is where my car usually sits with only one radiator fan on. With both on it gets slightly colder.

 

My 89, that tick is 195-200.

I believe my 91 is also similar temp range

 

So if that's the case then maybe my gauge is showing correctly for somewhere around 165? I'm not sure, I'll see if I can hit it with an infrared thermometer and check it accurately I guess as suggested earlier in the thread.

That would make sense though because now that I think about it, it sat right around that line all the time when I had the 195 in it when I got the car.

 

Yup i think you are in the 170 range based on that pic. When my car is about there, its 175's or so

 

Thanks, I just was worried because it looks like it's so ridiculously close to 100 and I tried to think logically with the gauge (which you apparently can't do) and thought that looked like it was running at like 130 all the time