Strange overheating

starspangled6.0 · Feb 15, 2013

Talked with the guy who drives the Sierra today... he said yesterday, when he was on the freeway doing 60, he noticed the coolant gauge was in the red, and it started going "bong bong!" with the "Coolant Overheating" message on the DIC. He dropped down to 55, and cranked the heat to full blast. 30 seconds after that, it was back to normal operation. He said as he continued to his plowing client, only cold air blew through the vents, unless he had it at full blast. Once he shut it off and restarted it, it was flawless for the next 9 hours of work. Ideas? Checked coolant level, and that's OK. I'm tempted to say maybe the t-stat is going??? Sounds more like an electrical issue then water pump or coolant leak.

01dually6.0 · Feb 16, 2013

Thermostat perhaps ?

starspangled6.0 · Feb 16, 2013

It's semi-normal for the trucks to run hot on the freeway with the plows on, and it was a fairly warm day, at about 30 degrees. However, the fact that it was blowing cold air for a while makes me think it wasn't just a fluke... and they can run hot, but never THAT hot.

starspangled6.0 · Feb 16, 2013

http://www.oreillyauto.com/site/c/searc ... hermostats

OK, which one should I get? I don't think the water pump has ever been replaced.

Parkrat · Feb 16, 2013

Bong bongs not good, if it cooled in 30 secs stuck t stat or fan belt would be my bet, maybe check the clutch fan.

starspangled6.0 · Feb 16, 2013

Hmm... he didn't say he heard the fan, which could be a) cuz it was 3:30 AM and he was tired; b) cuz he was on the freeway with a lot of wind noise; or c) cuz the fan is bad. How do I test it? Will it wobble a lot?

01dually6.0 · Feb 16, 2013

My 93 k2500 did the same thing just a few days ago been fine ever since . Just going to keep my eye on the temp guage . Except it didn't overheat just had no heat in the cab.

starspangled6.0 · Feb 16, 2013

Odd... I'll probably replace the t-stat and see what happens.

Parkrat · Feb 16, 2013

If the clutch fan is hooped it will move when you pull on the fan blade front to back, it should spin a little free when cold and lock up when hot.

camfire87 · Feb 16, 2013

I had a similar issue with an older truck of mine (except it had no computer to chime at me), and it turned out the problem there was that the external coolant heater that I had installed would plug up every now and then and not allow the antifreeze to get to the radiator. Not sure if you have anything like that installed, but worth a shot

starspangled6.0 · Feb 19, 2013

After running a few simple tests yesterday, we concluded that the fan was good, the t-stat was good, and it wasn't the coolant temp sensor. I called up my favorite local mechanic, and he guessed either the radiator had a leak, or it was covered in all the nasty cotton seeds we get from our cottonwood trees. Sure enough, we pulled the fan shroud off, and it had a nice blanket of cotton on it. I didn't expect that to fix it, but after a trip on the freeway with the plow wings fully blocking the airflow to the radiator, the temps wouldn't budge at all. Easy fix

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01dually6.0 · Feb 19, 2013

hogancarolyn060 · Jan 14, 2023

What would be wrong if a Chevy sliverrado 6-0 runs hot if you change the termasat and it still runs hot
And the fans not working

davester3500 · Jan 14, 2023

maybe make a new thread w make/model/year and your problem/info rather than adding onto a 10 year old thread...

Strange overheating

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