vandelay industries
1/2 ton status
As the title states, how hot is too hot for a small block? i think i cooked mine.
CK5
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How hot is too hot for a small block?
- Thread starter vandelay industries
- Start date
What year is it? Different years ran different thermostats which in turn run at different temperatures. I don't like to see any engine run over 210* and I would say at around 250* you're doing damage.
rompinstompinmudmonkey
1/2 ton status
I blew the water pump belt off my 383 in a mud pit. I didn't even know it was off until I got to the end of the run and realized that I had no steering. When I looked at my temp gauge it was pegged way past 280°. I opened the hood and rolled the belt back onto the pulleys and let the motor idle and cool down. I was so worried that I had hurt the motor, and this was only the 2nd or 3rd time I had used the truck since it was built. Anyhow, after the truck cooled down I parked it on the trailer for the night. I went out the next morning and looked at the gauge and it still read 220°! Apparently I had gotten it so hot that I bent the needle on the gauge! To my surprise, it never did any damage to the engine. I just installed a new gauge and have been running it for 5 years since
vandelay industries
1/2 ton status
260, and the temp light came on as well. Got stuck in a traffic jam with no fan. Long story, will get into more detail as time permits. Kinda busy now.
As long as you didn't spend too long there you might be okay. I had a radiator cap pop off when the retaining lip on the radiator cracked and it went to about 260. I filled it up with water and nursed it home, it was fine.
Ive got a motor that I built that has bumped 280 a couple times when I forgot to turn the electric fan on. I was always worried that I had done damage but I changed the oil on it and its kept going. Been about 7 or so years since that happened and its been swapped into 3 different vehicles and still keeps on going.
I think a lot of it has to do with the condition of the engine and the amount of time it ran at high temps as to how much damage was done.
On a side note I wheeled with a guy once that had a jeep with an amc motor that had an overheating issue for years. Always had trouble on the trail. One time in particular I remember him running the engine till it got so hot it would quit running. Let it cool for 30 min and take off again and repeat, all day long. Several years later when he swapped in an ls motor that old amc was still going, didn't smoke, use oil, rattle, etc.
I think a lot of it has to do with the condition of the engine and the amount of time it ran at high temps as to how much damage was done.
On a side note I wheeled with a guy once that had a jeep with an amc motor that had an overheating issue for years. Always had trouble on the trail. One time in particular I remember him running the engine till it got so hot it would quit running. Let it cool for 30 min and take off again and repeat, all day long. Several years later when he swapped in an ls motor that old amc was still going, didn't smoke, use oil, rattle, etc.
I seen TONS of overheat issues in the boats... suck a bag into a seawater strainer, bad raw impellor, etc..
sb heads don't particularly like heat, too dainty.. you'll blow head gaskets or warp a head.... that said, I've seen them survive 250+ on many occasions, but I have seen some failures at that point too...
BB heads can handle overheats much better than SB's with the extra meat surrounding coolant passages, etc.... much more stable..
sb heads don't particularly like heat, too dainty.. you'll blow head gaskets or warp a head.... that said, I've seen them survive 250+ on many occasions, but I have seen some failures at that point too...
BB heads can handle overheats much better than SB's with the extra meat surrounding coolant passages, etc.... much more stable..
63chevyll
1/2 ton status
I came off the track numerous times at 250when I raced. There was even a time when I thought it was done for and kept it pinned for a few more laps.
It was a well built...(kinda) 350 with good oil and after years of abuse and laps ran well over 230 it never blew a gasket or water pump seal.
As long as it doesn't boil your chances are good you won't damage. . When under pressure boiling point Goes way up. Typically if everything is holding pressure good the boiling point will be 260-270
So how hot is too hot....when it boils because there is no coolant to absorb the heat...even if it takes a long time
It was a well built...(kinda) 350 with good oil and after years of abuse and laps ran well over 230 it never blew a gasket or water pump seal.
As long as it doesn't boil your chances are good you won't damage. . When under pressure boiling point Goes way up. Typically if everything is holding pressure good the boiling point will be 260-270
So how hot is too hot....when it boils because there is no coolant to absorb the heat...even if it takes a long time
I got the 400SB in my 77 GMC K2500 so hot once the exhaust manifolds were glowing a dull orange!...I had been pushing deep wet snow across a large parking lot about 300 feet long,a good 20 minutes,when I noticed more steam coming out from under the hood than you'd normally see from melting snow,or the exhaust getting splashed on...then I smelled coolant,and saw the temp gauge was pegged..it peuked out of the overflow bottle..after it cooled off I refilled the radiator,and it only went up to 180 degrees,the 195 thermostat was now stuck open I assumed..
That engine got overheated probably 10 times,until I learned you could "lock" the fan clutch spring so it would stay "on" constantly--until then,every time I drove the truck with the plow on it over 30 mph for more than 5 miles ,it would peg the needle and start peuking out of the overflow tank..I had tried numerous thermostats,leaving it out,etc,to no avail...locking the fan clutch solved the problem 100%..for free,after wasting money and time on it..
I thought sure I'd at least blow a head gasket,with the 400 SB being the most "fragile" when it comes to overheating,and having siamesed bores..but it never used any coolant,or got any in the crankcase..
I remember a friend's '72 Nova that had a 250 six getting so hot one night on the highway when we were returning from a night of partying ,that the exhaust manifold and part of the head it bolts too was pumpkin orange,when we pulled over to see why the "temp" light came on,we saw the lower hose had ruptured at the water pump,a nice rip in it 3" long..when it blew,it took out the bottom row of tubes in the radiator too,it was all gangrene and paper thin,many fins were missing too..
Not wanting to have a cruiser pull up behind us and possibly get pinched for DWI,my friend decided to just get back in the car,FLOOR it,and drove it the remaining 8 miles to his place..we made it there,but it sounded like it had a piston so loose it was flopping around in the cylinder,it was pinging BAD the whole way there too--when he went to shut it off ,the engine actually smoothed out and ran BETTER that it did with the key on,and the pinging stopped!..we had to open the hood and close the choke to smother it to shut it off!..the exhaust manifold was orange and the head was a dull red color...I got my hand burnt pretty good holding the choke shut long enough to snuff out the engine..
The next day we found a used radiator and got a new hose,we put them in,and I told my friend,not to be too dissapointed if the engine was junk,if it would even run,it might have spun bearings or at least a blown head gasket..but to our surprise,it started right up,the lifters clattered for a few minutes,then quieted down one by one--after 15 minutes,it ran just as nice as it did before the overheating dilema happened..he drove that car another year before he sold it...said he never added any coolant to it either,it stayed full...
..I gained a lot of respect for straight six Chevy's after seeing that one withstand that abuse..
That engine got overheated probably 10 times,until I learned you could "lock" the fan clutch spring so it would stay "on" constantly--until then,every time I drove the truck with the plow on it over 30 mph for more than 5 miles ,it would peg the needle and start peuking out of the overflow tank..I had tried numerous thermostats,leaving it out,etc,to no avail...locking the fan clutch solved the problem 100%..for free,after wasting money and time on it..
I thought sure I'd at least blow a head gasket,with the 400 SB being the most "fragile" when it comes to overheating,and having siamesed bores..but it never used any coolant,or got any in the crankcase..
I remember a friend's '72 Nova that had a 250 six getting so hot one night on the highway when we were returning from a night of partying ,that the exhaust manifold and part of the head it bolts too was pumpkin orange,when we pulled over to see why the "temp" light came on,we saw the lower hose had ruptured at the water pump,a nice rip in it 3" long..when it blew,it took out the bottom row of tubes in the radiator too,it was all gangrene and paper thin,many fins were missing too..
Not wanting to have a cruiser pull up behind us and possibly get pinched for DWI,my friend decided to just get back in the car,FLOOR it,and drove it the remaining 8 miles to his place..we made it there,but it sounded like it had a piston so loose it was flopping around in the cylinder,it was pinging BAD the whole way there too--when he went to shut it off ,the engine actually smoothed out and ran BETTER that it did with the key on,and the pinging stopped!..we had to open the hood and close the choke to smother it to shut it off!..the exhaust manifold was orange and the head was a dull red color...I got my hand burnt pretty good holding the choke shut long enough to snuff out the engine..
The next day we found a used radiator and got a new hose,we put them in,and I told my friend,not to be too dissapointed if the engine was junk,if it would even run,it might have spun bearings or at least a blown head gasket..but to our surprise,it started right up,the lifters clattered for a few minutes,then quieted down one by one--after 15 minutes,it ran just as nice as it did before the overheating dilema happened..he drove that car another year before he sold it...said he never added any coolant to it either,it stayed full...
..I gained a lot of respect for straight six Chevy's after seeing that one withstand that abuse..
Do yourself a favor and change the oil, especially if it's not synthetic. That hot can ruin the lubrication properties of conventional oil, so it's always in your best interest to change the oil ASAP after it gets above about 230 - 240. You might be OK, but you'll never know for sure until you get some more time on it.
