Temperature weirdness!!

Braylen0827 · January 3, 2022

What’s up guys, I got a ‘07 Sierra with the 5.3. I’ve replaced the thermostat and it’s not really a issue but sometimes the temp will creep to 215-220 (the space between 210 and 230) and once the fans cut on it’ll go back down. It’s currently 30 degrees in Alabama and she’s still doing it. Kinda seems like it does it more than when it’s warm. Any ideas? Like I said I don’t really see an issue since the fans cut on like they’re supposed to and cool it back to 210, but personally I’m an over thinker and I’m looking for someone to say don’t worry it’s all good. Thanks guys!

Grumpy Bear · January 3, 2022

Back in the day fans ran all the time. Talking pre-clutch days. So air was always moving over the radiator. Todays electric fans mean zero air flow stopped and low at city speeds. Well in town everyone likes to run 3" from the guy in front of them. Hum...highway too I guess. So yes, they move more and spike higher. Normal.

Braylen0827 · January 3, 2022

3 minutes ago, Grumpy Bear said:

Back in the day fans ran all the time. Talking pre-clutch days. So air was always moving over the radiator. Todays electric fans mean zero air flow stopped and low at city speeds. Well in town everyone likes to run 3" from the guy in front of them. Hum...highway too I guess. So yes, they move more and spike higher. Normal.

I appreciate the response! It was just weird because even in 30 degree weather it’s still doing it, almost more than usual. And too I hadn’t seen it creep up like that before while sitting still until recently.

Supreme Pizza · January 4, 2022

1 hour ago, Braylen0827 said:

I appreciate the response! It was just weird because even in 30 degree weather it’s still doing it, almost more than usual. And too I hadn’t seen it creep up like that before while sitting still until recently.

I could be wrong, but I think you can regulate the temperature if you want. You could use a higher or lower temperature thermostat, you could reprogram the computer to run the fans in a tighter temperature range, you could disconnect one of the fans, and hook it up to an adjustable mechanical thermostat that triggers it on/off, you could add an extra "pusher" cooling fan that runs 24/7 when the engine is on, etc etc.

I have an '08 with a 5.3, and the temperature is always stable. No fluctuations, after warmed up.

Edited January 4, 2022 by Supreme Pizza

CamGTP · January 4, 2022

Try to verify the actual temp with a handheld scan tool.

The temp reading of 210 on the gauge is not accurate, it's more like 190-195 in those year trucks. The stock thermostat is a 192 or 194 if my memory is right.

I don't see an issue at the moment with what it is doing. But you could also test the radiator cap to make sure it's holding proper pressure and also back flush the fins on the radiator with a hose if you have never done that. Lots of dust and dirt get in there.

Braylen0827 · January 4, 2022

3 hours ago, CamGTP said:

Try to verify the actual temp with a handheld scan tool.

The temp reading of 210 on the gauge is not accurate, it's more like 190-195 in those year trucks. The stock thermostat is a 192 or 194 if my memory is right.

I don't see an issue at the moment with what it is doing. But you could also test the radiator cap to make sure it's holding proper pressure and also back flush the fins on the radiator with a hose if you have never done that. Lots of dust and dirt get in there.

Man I appreciate the response! The fans are cutting in at 215-220 which everything I’ve read says that they’re intended to kick on at 220. I’m mainly just making sure the temp is suppose to creep up when sitting still like that. Trying to ease my worries. Thanks again!

Grumpy Bear · January 4, 2022

1 hour ago, Braylen0827 said:

Man I appreciate the response! The fans are cutting in at 215-220 which everything I’ve read says that they’re intended to kick on at 220. I’m mainly just making sure the temp is suppose to creep up when sitting still like that. Trying to ease my worries. Thanks again!

It will go that high 'sitting still'. Not to worry. A 50/50 mix of glycol gives a 223F boiling point without pressure. You have a 15 psig cap raising that to 268 F as sea level.

Sharpz · January 4, 2022

as stated above try to verify your actual temp vs what the gauge is saying. MAKE SURE you have removed all air from the system by following the proper procedure.