Driving home from work the other day I noticed my temp gauge slowly start to climb above normal. I continued to drive for another 2-3 miles to the nearest gas station where I could stop. As I continued the next couple minutes the temp gauge continued to climb into the high range. I have an OBD 2 reader that Bluetooth connects to my phone, I checked the coolant temp as I was heading to the gas station and it was reading around 116 celsius. The gauge was near the H line by the time I got to the gas station and shut it down and the “check gauge” light had come on. I live in Iowa and the temp was around 30 degrees that day. I let the engine cool down for around 15 minutes by which time the temp gauge had gone down close to the L mark being that it was cold outside. I checked the radiator which was dry, the cooling system had sprung a major leak during the drive and all the coolant had leaked out. I bought some coolant at the gas station and added a gallon to the radiator which immediately began to leak out on the ground from somewhere. It was only maybe 4-5 miles home from where I was and I figured with at least some coolant in the radiator and the engine cooled back down I could make it home. The temp gauge slowly began to climb above normal range as I drove the rest of the way home but it was only about a 5 minute drive and the gauge didn’t quite reach the high end before I was home and shut it off. This engine has never been overheated in its life, and has always run perfectly, it has around 130,000 miles or so. The duration of the entire trip from work to home including the stop wasn’t more than maybe 30 minutes, and only a few of which maybe 5-10 minutes at the most was the truck was running hot. Assuming the head gaskets are good which I believe they are (the engine oil is perfectly fine, no white smoke from the tailpipe, and the coolant leaks out in a steady stream whether running or not) what are the chances that a short duration overheat could have caused cracks or warpage to the heads etc.? I’m trying to track down the coolant leak and what it may cost to fix it and if it’s worth it if there is potential overheat damage, any input would be greatly appreciated.

 

I had a heater hose line pop off while going 55 down the highway sometime in 2016 or so. I had to wait a few minutes before I found a spot that was safe to pull over. My truck was pouring white smoke from the coolant dumping on the engine, but it was all from the front and not the tailpipe.

The temp gauge didn't max out but was in the high range. Luckily for me, I always keep a gallon of coolant in the toolbox, so once I found the leak, I fixed it and then added coolant back into the radiator after it simmered down. I then drove to the auto parts store to buy another gallon but realized I hadn't lost as much as I thought and therefore didn't need it.

It is now 2023 and I'm still driving the same truck with the same engine (3.0). Never had issues with overheating after that and haven't noticed any long-term effects from it. From my experience, there is a chance that it is fine.

However, the 4.0 OHV heads are known to crack after overheating. If you notice you're losing coolant even after you fix the leak, or if you notice any performance issues or white smoke from exhaust, you may have cracked one or both. You'll just have to keep an eye on it.

 

I doubt you damaged your engine.
Lower radiator hose at the pump is my guess.

 

I found the coolant leak today, unfortunately it’s coming from the rear of the passenger side head gasket. If I add coolant to the radiator it immediately leaks out at a rate of a gallon in 15 minutes or so. The gasket failure is from the coolant gallery to the outside of the engine on the back side of the head, the oil is perfectly clean and at its normal level and the truck fires up and sounds and runs totally fine, no white smoke, never lost power or misfired etc. so no signs of internal gasket failure which I guess is good but the fact that it hit 116 celsius for 5 minutes or so which is 240 Fahrenheit worries me about about head cracks, I have no idea how much abuse the heads can take but people seem to say they crack easily even with a single overheat.

 

Too bad about the leak. Head removal for gasket replacement will give you the opportunity to inspect fully.
The head might not be cracked.