I started my charger this morning after unloading from the trailer, walked away to go get a wrench from the garage, gone about 5 - 10 min or so. when i came back to get to the car i noticed the temp gauge at 255 degrees. My electric fan never came on. Found the relay failed. Would that 255 - 260 degree coolant temp hurt the motor? Its a 440 ,trick flow heads. never runs hot otherwise. I did a compression test all cylinders at 210 - 215 psi.
Anyone have a similar experience ?

Did similar thing twice just last year. Left a little cruise in place in my low 11 sec 360 powered 69 Dart.
Pulled out after dark, and forgot to turn on both the electric water pump and fan. Got back to my shop with the car before i noticed it... was at 250-260....
Did the exact same stupid thing about a month later. Went to same place, did same thing
Raced the car afterwords, extensively, zero issues. Probably 60-70 passes, and more street driving. Car was fine.
Pulled the heads off over this past winter, everything looked great. Got very lucky.
Since have sold the motor and installed a small block stroker in the car

I've seen that happen more than once, me included on the switch being for gotten when warming up the car and also popping a fuse once..
My thinking is as long as their is liquid coolant in the heads and block your good, even if the radiator cap opens and dumps a bunch of coolant out

thanks for the input. the coolant had not boiled over, so that's my hope. I tend worry a lot....lol

While mine didn't get quite as hot, 240 degrees at least, it was up there for what seemed like an eternity (better part of a half hour). Idling through traffic trying to get into the airshow. It seemed fine afterwards

My 528 got at least that hot at least once and had no ill effects.

Don't worry about it. Had the same thing happen to my hemi.

Same here. Water pump motor locked up. My pit neighbor told me that stuff you're not suppose to have in your cooling system is running all over the ground. Gauge was pegged. Fixed the pump, topped it up and away we went. No further problems.

Brian

Similar happened to me once. Came back after a run and she boiled over. Temp gauge was pegged! Blew the fuse to the water pump. Let it cool down and topped off the water, changed the fuse and finished out the day!
If you had a 15# radiator cap on it that should raise the boiling point to 268 degrees. I don't think you damaged anything.

I have a16# cap on it and it didn't boil over but started to fill the catch tank. i think the engine is fine . had it running today all sounds same as usual . thanks for input guys.

I got my street rod that hot 2 years ago.. I didnt like it but it didnt hurt anything

I had a 318 TBI dakota when I moved here, between tools in the bed and trailer I was hauling over 10,000lbs and the temp ran constantly around 240-even 250 occasionally when pulling hills over the course of 2000 miles and never seemed to hurt anything but I was sure frazzled over it the whole way with the heat cranking in 100 degree weather, drove it thousands of miles after I got here with it and never had an issue and didn't ever run over 200 when not towing. I bet if it had aluminum heads it would have dropped a valve seat.