08 Silverado Overheating!!

[Rubicon500]

Last week, i ran into a store to pick something up and i left my truck running as my wife was sitting in it... came back and noticed that the engine temp was higher than normal!!

 

Once i started driving, it returned back to normal operating temperature. Since then, i have been keeping an eye on my temperature gauage. My observations have been that while driving the temperature is reading as it should, idling at a stop light for a couple minutes are fine, but when it's idling for 5-10 mins it starts to get hot. This problem has NOT resulted in a check engine light.

 

I have an 08 silverado with the 4.8L, and 130,000kms

 

I have never cleaned the throttle body on my truck, so i'm going to do that tonight.. as my idle bounces around quite a bit.

 

Could the thermostat require replacement?

 

Any help with other things to check to narrow down the problem would be much appreciated!!

 

Thx!

[Jsdirt]

Check the fans - sounds like they're not working.

[Rubicon500]

thanks.. i will

 

What would cause the fans to not work?

[Jsdirt]

Could be anything - crappy motors, loose connection in wiring, really low on coolant, or bad temp.sensors.

 

If I remember right, one kicks on before the other - so the sensor for each fan will have a different kick-on temp. ... or the computer controls them (more than likely these days).

[Rubicon500]

much appreciated!

i know my coolant level isnt low... but i'll have a look at the fans tonight.

[Jsdirt]

No problem. Let us know what you find - keep us posted.

[Doug_Scott]

Just because the engine temp is higher than normal does not mean it is overheating. When it overheats it will push hot antifreeze out of the engine, into the overflow bottle, then once that is full, it goes to the ground.

 

It is normal for temp to fluctuate when the truck is just sitting there idling. The hotter the day, the more often it will heat up then cool down. If you have the a/c on, the fans should be running all the time (that the compressor is engaged) when stopped with engine running.

[desrtrat]

what do you consider hot. 20*-50* hotter?

[Rubicon500]

based on what doug was saying it wasnt overheating....

my needle was about half way thru the zero on the 100 reading (210)

 

i'll try the ac to see if my fans work

[Jsdirt]

That's normal on these things nowadays - 210° is straight up at 12 o'clock on the gauge - perfectly normal.

[Rubicon500]

yep... but it's on an angle thru the middle of the zero... it's not straight up

[Jsdirt]

Well then yours runs cooler than mine. Ever since mine left the lot, it runs right up to 210° and stays there, unless I'm towing over 5,000 lbs. up a long grade, A/C on, on a 90°+ day - in that case it will pass 210° until I crest the hill.

[Rubicon500]

but.. mine is to the right of center, goes thru the middle of the '0' digit.. and that's at idle with no AC on

 

i attached a drawing... trying to show what i mean.

[Rubicon500]

pic attached

[Jsdirt]

AHH ... I gotcha now. That's the problem with internet diagnosis!

 

To the right of 210° is hot - so if it's only happening at idle, then it should be a fan issue.

 

If it's not puking coolant out I wouldn't worry about it ... unless it's getting close to 260°. Factory gauges aren't noted for their superb accuracy. A scan tool will tell you what the sensor is reading, but I'd rather use an infared thermometer on the t-stat housing, or a cylinder head to know for sure.