2014 GMC Sierra Overheat Warning

[jwasbury]

Bought this truck new in late 2013, was one of the first new 2014 models at the dealer.

Driving home tonight towards the end of my 80 mile commute, I'm climbing a short but pretty steep hill on a country road that you enter on a sharp curve so you are accelerating pretty hard up the grade from a low speed. About at the top of the hill, the truck throws a warning message in the DIC that reads: "Overheat Warning Idle Engine."

Never seen this before...look at temp gauge and its pegged at 260...top of the range. Oh crap. Already out of the throttle at this point as the grade has leveled off, I am looking for a safe place to pull over and have my eye on that temp gauge. Within seconds, the temp gauge moves rapidly back to the normal operating point (210) and in another minute I'm safely pulled over. Pop the hood...nothing strange happening. Get back in and drive the remaining 10 miles home. Temp stays at 210. Saw it climb up a little at one point, then quickly back to 210.

Any ideas what might be happening? Never any low coolant or other cooling system warnings on this truck before (about 57k miles on it). I have a hard time believing that the coolant was 260 degrees and dropped 50 degrees in 5 seconds.

[john70t]

(I don't know so please disregard the following as junk)

As a possibility:
1). The coolant temp sensor might be located near the head/block or the exhaust manifold exfil ports.
Those areas could rise quickly under duress and lower just the same.
Do you know where the coolant temp sensor is located?

2). Coolant absorbs heat.
Driving on the highway and pegging on a small hill doesn't make sense at all.
Is there something else missing?
Like radiator fan/switch/headtemp/other?
Probably not but it is worth mentioning.

3). Start with any OBD2 codes thrown in memory.
The computer knows all.
hahaha.

[Nickshu]

Sounds like a sensor error as said above. Which engine? 5.3 or 6.2? I have a 6.2L 2014 and it has been flawless. Have about 40K on it now.

[john70t]

Any TSBS/recalls on that model?

[onewhippedpuppy]

Any chance you recently filled up with gas? I had a similar issue on my Ecoboost F150 tuned for 91 octane on a hot summer day while pulling my boat on a hilly road immediately after filling with gas, I'm convinced it was bad gas. I limped home at a lower speed with no AC, filled up at another station, and the issue never came back.

[VincentVega]

Pressure test it. I saw a bad cap on one recently. If no leak and the cap is good check the temps pre/post thermostat warm.

[timchar]

I presently have a 2014 GMC 1500 5.3, 80k no problems at all. My 2006 had same overheating problem, think it was a temperature sending unit? Was long time ago. My employee has the 2006 now, it has 200k miles, been a great truck. I've had very good luck with GMC trucks. Good luck, Tim

[speeder]

Tim and Jacob, just curious how you've gotten that many miles. Long as heck commute? Lots of long distance driving? 10 hours a day driving it?

I'm always curious about this. The most I've ever put on a vehicle is prob 20k in one year.

[jwasbury]

Guys this is a 5.3. Will see about the cap and pressure test. I have noticed I sometimes catch a whiff of coolant around the truck, but never seen any leakage. Maybe that also points to the cap?

The truck has been great...no issues. It throws trailer brake controller failure warnings once in a while, but the brake controller seems to work whenever I'm pulling a trailer.

There have been a bunch of recalls on the truck, mostly not related to the driveline...all have been performed by the dealer.

Dennis, this isn't a daily driver, but somehow I manage to rack up miles. Use it weekends mostly running between NYC metro area and my country "estate" in Bucks County PA, and running up to the racetrack. I've used it for a couple long distance road trips, but 90% of the mileage is within 150mi radius of NYC.

[timchar]

Originally Posted by speeder

Tim and Jacob, just curious how you've gotten that many miles. Long as heck commute? Lots of long distance driving? 10 hours a day driving it?

I'm always curious about this. The most I've ever put on a vehicle is prob 20k in one year.

I drive daily to 8 different business locations in a 45 mile radius. 5 locations are actually in one town, so lots of in town driving as well. Thankfully, these trucks drive like luxury cars. My dad always drove GMC, I'm following his footsteps. Also have the Denali Acadia I really like. Tim

[berettafan]

whatever you do, do NOT google 'GM AFM' or '5.3 AFM'.

it is a wonderful motor/platform when it's working well.

[timchar]

Originally Posted by berettafan

whatever you do, do NOT google 'GM AFM' or '5.3 AFM'.

it is a wonderful motor/platform when it's working well.

I'm aware. I don't live in a very cold climate and I don't let it idle for long periods.
Also carry a fire extinguisher. Tim

[berettafan]

it scared me out of a '13 suburban that I otherwise loved. gm does a fine job making a truck comfortable and the 5.3 feels great. soooo smooth and sounds great.

[bkreigsr]

Any traces of coolant in the oil? (head gasket)
That might explain occasional antifreeze odors?
Bill K

[jwasbury]

Never noticed anything strange with the oil. I've done a number of oil changes myself, but the dealer has done most of them.