My engine got 250 degrees or so while idling. Wasn't driving or anything it was just parked while I was checking for exhaust leaks. It runs fine and no signs of coolant loss but just curious what the danger zone is

 

You say LSX....do you mean the iron LSX...?

Or do you mean the aluminum block?

Aluminum......they can easily handle the temp needle being buried all the way into the red....as long as you don't let it stay there and get pulled over and shut the engine off.

I've lost my serpentine belt while doing 150mph and didn't know till I looked down and saw the temp needle buried all the way to the right into the red, so no idea how long it was there. The run was maybe 30 seconds. Then the time to pull over. I turned the engine off at 150mph and rolled to a stop on the highway.
When I stopped, there was steam coming out of the plastic overflow tank and I lost most of my coolant. I had one jug of water with me, an old anti-freeze jug full. I waited about 20 minutes. Then poured that jug in....the temps were way down to like 180-190 (on the guage). I started it up and drove it about 1 mile to a place where I could park it. The temp never went much higher during that 1 mile drive.

This happened to me again about 1 month later....same exact thing.

Then I bought the Katech belt tensioner and solved that problem...

I also over-heated all the way into the red while cruising at 75mph one day when my coolany had finally gotten so low that it stops circulating......bad water pump that had been leaking for a few days and thats where all my coolant went. I know I was driving for a few minutes that time before I scanned down to check my guages. Good thing I'm a professional pilot and used to scanning instruments often....I could have seized my engine that day.

Anyway....my engine was never hurt in any way.......aluminum is very resilient.
Iron....from what I've been told, you better never let it get that hot. It will warp........

You're engine is just fine.....I wouldn't worry at all. These aluminum engines can easily see the red zone at high rpm's doing 150mph. So at idle, no worries at all.

For aluminum......I believe you will seize the engine from expanding pistons in the cylinder before any part of the block or heads has a problem.

.

 

You are in the newer Gen V LT1 section. You'll get more responses in the LS section. Bob

 

Pretty much the same thing happened to me. Car lost a belt around 150 and I noticed the power steering was gone. Pulled over to check it out and the car started screaming at me about overheating. I turned it off and she puked a lot of coolant. I changed the oil and added coolant that night and it was good to go. Before my radiatior upgrade I would see 220 on a hot day. 250 is a little high though. I would look into at least an upgraded fan or better radiator sooner rather than later.

 

im trying to find a 160 t-stat for mine its the l83 ecotec 3 5.3, its killing the tranny clutches with the stock 210 t stat

 

Why not get a transmission cooler?

 

why spend 120 bucks on a cooler when a 20 dollar t stat is an improvement for the engine and trans

 

Simple, Just because you put a 160* thermostat in does not mean it will run that cool and in most cases they don't. Thermostats only regulate minimum temperature not maximum temperature so they do little for an engine that is running to hot already, The only way to cure that is to increase cooling capacity.
PS not sure where you buy trans coolers but I buy good kits for less than $60.

 

you have to reprogram the on off temp for the electric fans to do it properly.

 

not really. if the ambient temp is less than the exchange medium, you get cooling. heck just adding the few quarts fluid capacity drops temps 10*

but yeah, turning the fans on earlier would be nice too.

 

Had mine at 270 a couple of times this summer after losing a belt during a pass. Both times freaked me out bit it seems to be fine. Aluminum 5.3