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Sudden overheating

Yesterday when I was driving home my temp gauge went up to H, I turned the heat on full blast and drove 15 more minutes home. The radiator cap was slightly askew and coolant had come out, although the reservoir is full. I just checked this morning and the coils are visible. I turned it on for two minutes, not long enough for the temp gauge to rise from C, no coolant seems to have left the reservoir but it looks like it leaked from the top of the radiator from where the two parts come together. What happened? It was very hot outside, truck has 92k miles

Sounds like your radiator or cap failed. The radiator needs to be filled with coolant via the filler on the radiator. You may need a few gallons. Certain engines need additional steps to make sure the engine if full of coolant. If you know the engine size and year you can post it if you need directions.

You may need to fill the radiator itself. Make sure you use the correct fluid. It likely will take a long time using the over flow tank to refill it.

Howdy. I think both answers are on the right track but the definitive one is to get your cooling system including the radiator and cap itself, pressure tested at either a radiator shop or garage. It’s a very easy test, probably won’t cost you anything and would tell you if the cap is good, whether the radiator is leaking or whether you have a small leak somewhere else in the engine like a freeze plug or gasket somewhere like water pump or thermostat. They can also easily check for a blockage in the tube between the reservoir and radiator to ensure coolant would travel freely back and forth.

The other thing to double check is the concentration of your system coolant. Water will boil at a lower temp than water w/ proper ratio of antifreeze. And if you engine simply overheated, it’s also quite possible the cap popped loose (rather than entirely off) to “blow off steam” and increased pressure from the overheat. ;>)

Thanks guys. Looks like 9 liters. Hope I didn’t wreck the head gasket

I will do that. so probably if I make sure there is a proper level of fluid and monitor the temp gauge (stop driving if it overheats) I could drive it to the shop without causing more damage?

Chances are if it was running ok when you turned the engine off you will be ok. Get the leak fixed or buy stock in your favorite antifreeze company :slight_smile: