I overheated it, how fast does it take damage?

[shadow460]

I had changed a leaking water pump. To that point my truck has never been low on coolant nor has it overheated while I have owned it. It took a little over a gallon of coolant and I fired it up. It seemed to take the usual amount of time to warm up, during which I hooked up a scanner and watched the scanner's rpm and coolant temp readouts like a hawk. The stat opened and the temp rose from 180 to 212 degrees. I shut it down at 225. The dash gauge was 3/4 of the way up. Once I shut it down the gauge went just barely to the red and the scanner said 255! That's the highest it got. I hope I didn't kill the engine. It's a 4.0 SOHC.

 

[XLTrunner]

You're fine. Temps will rise somewhat after you shut off the engine since it's no longer circulating through the radiator. You certainly want to monitor the engine temp when running/driving as 225 is at the high end of what's tolerable.

 

[shadow460]

It cooled down and I added more coolant, burping the system as much as I could. Temps were 180 to 192 on the test run, usually hovering at 183. It's given me no indication of issues and runs like Forrest Gump. Tomorrow I'll clean up the engine bay and then keep an eye out for leaks.

 

[koda2000]

I suspect you had a little air trapped in the system when you first ran it, If it got too hot and you turned it off right away I doubt you hurt anything. You say you added more coolant afterwards, so that says it needed to be burped. 192 F is what it should run at with a good t-stat, so you're fine now.