Nominal Operating Coolant Temp?

[skid542]

I just need a quick verification, nominal coolant operating temperature is between 180* - 200*F? I ask because my dash gauge seems like it's getting a little high, but I've had the dash/gauge cluster pulled and replaced the sending unit so it may be out of "calibration". Vikash's scan tool has been registering between 183* - 194*F. My fans haven't been kicking on though, or atleast I haven't seen it happen yet.

I just want to make sure that all is well and I'm not overheating my engine again.

Thanks in advance.

[vrg3]

Yes, 180 degrees to 200 degrees Fahrenheit is normal. The thermostat opens at about 180 degrees and the fans turn on at about 200 degrees.

Since they're separate sending units, though, it is possible for an air bubble to pass one and not the other.

And of course there's also the possibility that it's the ECU's temperature sensor that's not doing its job properly, though that seems somewhat unlikely if you are seeing about 180 degrees on the low end, since that's not electronically controlled.

What does "a little high" mean?

[skid542]

The needle is getting above the half-way mark, around 5/8's, though it still staying mostly at the half mark. It's at idle at the stop light that it gets high.

When I get on boost and get moving, it'll drop down to 173-175 for a brief minute. Keep in mind that ambient temp is ~38*.

I'm doubting the sending units are bad. I replaced them during the HG R&R with brand new units.

The overflow tank hasn't been overflowing either.

[vrg3]

Hm. That all sounds okay (the reason it drops below 180 is that so much cool air is passing over the radiator while the thermostat is still in the process of closing), except for the needle going that high.

[Legacy777]

Since I had been having some of my own issues, I looked up the info.

The thermostat starts to open between 169-176 deg F, and is fully open at 196 deg F.

The fans kick on at 203 deg F, and shut off around 190 deg F. Note the shut off temp for the fans was me looking at the select monitor. I'm pretty sure that's correct, but with some of the issues I've been having, I'd have to double check.

[BXSS]

I had a similar problem on the OBS-t with a Crucial Racing 160* t-stat.

On highway cruise @ 60ish MPH the temp would creep to 200* (I have a gauge), but if I stomped on the gas (high RPMs) the temp would drop down to 150-160* (OEM gauge read normal temp slightly under 1/2 way).

I swapped my Koyo Rad in thinking it would cool the car down, but the problem persisted.

I then put a stock t-stat on the car & all was well.

The Crucial Racing overpriced, POS, same brand as autozone t-stat was causing the problem.

Change your T-stat.

[93forestpearl]

I always preach of using an OEM thermostat. All others I've seen are puny in comparison, ever Superstats.

OEM compared to Napa:

[skid542]

Thanks for all the input guys. I'm glad to see that the experts jumped in .

I know it has a new T-stat, though I don't know if it's OEM or aftermarket (the shop did it back in Oct. at the beginning of this adventure). However, I have yet to see a temperature above 195*. I think my dash gauge is just a little sensitive but it seems to be settling out now that I've put 20-30 mi. on it. I'm atleast comfortable enough that my engine isn't overheating and that was my main concern.

Thanks again guys.

[Legacy777]

If you're in question.....replace the tstat with an oem one. It will cause you nothing but endless problems if you don't have an OEM tstat.