I have a 2014 GMC Sierra 1500 with the 5.3 and 144,000 miles. I've towed a 4300 pound camper around the Colorado mountains multiple time this summer with no problems. Temperature never went above 210, maybe 220 once. I took it to get an oil change last week and they also changed the coolant. I drove around for 40 miles that day stopping for extended periods of time to do errands and it was fine. I then picked up the camper from getting repaired, another hour+ stop and headed for home. I stopped again twice to check and make sure the camper repairs were in fact fixed after driving at highway speeds. After the second stop I didn't make it far and my truck was overheating. I was going up the large hill out of Denver, but I've towed the camper up this and similar hills all summer long with no problems. The pull over and idle alarm went off and I pulled over and let it cool down. I started going and it heated right back up. I turned around to heat downhill to a place to buy antifreeze and the alarm to pull over and turn off engine when off. At this point there was no sign of leakage from the overflow. The owner of the garage that service the coolant system was super nice and brought antifreeze but the truck overheated again in 3/4 of a mile. Now there was antifreeze sprayed all over and my truck needs at least a new water pump and thermostat. The thermostat was replaced six months ago. Could most of my antifreeze have evaporated like the shop owner said or did they not fill it back up properly? There was minor white around my reservoir cap when I first stopped. Did the thermostat fail in the closed position? Is it a coincidence that my water pump or thermostat failed right after they serviced the system or did they not refill it properly and those things were damaged because of the overheating?


could my reservoir look like this after evaporating a gallon and a half of antifreeze?

I'll take it piece by piece . . .

So 6,000 miles before the first coolant service is needed. Good job staying ahead of schedule!

Easily below this truck'* tow rating no matter the drivetrain.

No worries here.

So 144,000 miles and it is fine. Then coolant change, some short errands with lots of cooldown time, and then first real work and it is overheating.

I know these hills well, especially while towing.

By idling, right? Not by shutting the engine off I hope . . . ?

Getting hot that quickly makes me suspect a blown head gasket.

Very nice of them, especially because they are the the last ones to touch it.

So no sign of a leak while overheating, then fill coolant back up and it immediately sprays antifreeze all over? This also tells me blown head gasket is likely.

Why?

What in the world would take them from working fine to this so quickly and easily?

At the end of this post I'll posit my theories.

Even the cheapest thermostat will last longer than this if it isn't defective out of the box. Six months of service confirms it was not defective out of the box.

No. Normal automotive coolants don't evaporate. Well actually they do, but over a very long period of time, like years. You can boil coolant, but in your system you'd have to get it over 270 degrees Fahrenheit to do that, and at that point the engine is toast anyways.

A shop owner that claims anything like this, especially in your situation, is trying to pull a fast one on you. Next time he tries this, ask: Really? So my coolant didn't evaporate for ten years and 144,000 miles, then your shop changed it, and now it evaporated in a day? What kind of coolant did you use?

This ^^^^^^^ is more likely, but wait until the end . . .

I can't speak to this. If there was no failure, this minor white may have gone unnoticed for 144,000 more miles. It might have been there before this work but nobody was looking closely at it.

I doubt it.

I'd bet on they caused this one way or another.

Okay, now we're at the end. Here goes:

There are several ways to "change coolant".

If they just drained it and filled it then they'd have to work air pockets out. If they don't, it is likely you could drive around for short trips and never have a problem with adequate cooldown cycles. The first time it has to really work, if there'* an air pocket in the right place, all kinds of bad things can happen.

If they flushed it, same thing can happen. Depends on how they flush it and what they use to flush it.

If they pressure flush it, I've seen yahoos run 120PSI compressed air through with a radiator flush tool then wonder how gaskets and seals are damaged afterwards. Duh, a 16PSI cooling system should never have 120PSI of anything put through it.

If they actually flushed it, they'd have to remove the thermostat, so there'* another possible point of failure/damage/poor workmanship.

If the water pump is suddenly leaking a lot and it had no leak before, then that'd be a sign that it was pressure flushed at too high of a pressure. If a head gasket is blown, that could be a sign of the same, but more likely there was air somewhere and the head got hot.

I wasn't there, so I don't know what exactly was done nor the reputation of the shop. I do know that it is hard to get any engine in your 2014 1500 to overheat after a coolant change without doing something extremely careless or stupid. The V-6 and the V-8'* have great reputations this way. Regardless, I'd take it back to them and point at it . . . or alternately if you don't trust this shop, find a reputable shop to diagnose it. Personally, if the owner of a shop claimed to me with a straight face that it is possible that the coolant evaporated in that short of time, I'd run screaming away from that shop.