I have a 4wd 2004 Blazer LS with 190,000 miles. I just replaced the entire cooling system and it doesn’t even come close to overheating when running or even at idle but if i drive for awhile than park it at the house it’ll overheat while it’s turned off in the driveway. It’s still around 70 degrees here outside so that shouldnt be a huge problem, but i’m confused on why it’s doing this. i’ll park it at 210 degrees than come out half an hour later turn it on and it’s at 230/235. Please help!!

 

Adam
This is what I call it; cook off, you have been running your engine and you now shut it off. You no longer have coolant circulating and your cylinder walls are still hot so heats up the coolant around them and temperature of coolant is heated up. I would think as long as your recovery tank is catching the cook off excess it should not be a problem. I live in Hawaii and going to the house elevation raises from 100 feet to 2500 feet in just a few miles. I had trouble losing antifreeze and replaced radiator and intake manifold gaskets. If i push it hard sometimes let it idle while I unload the groceries, just to let it cool down. My thermostat is 195 and temp stays in that range. Arriving at home it can be about 200. Antifreeze does transfer to recovery tank; but that is what it is suppose to do. I will make a point of checking 1/2 hour later and see what it reads and let you know. Ocean side temp at this time of year is about 95.
L

 

Thank you, yeah i normally just open my hood and it’s fine but it’s rather annoying and embarrassing in public lol. it doesn’t get to bad but it slightly worries me. appreciate your input.

 

What's the pressure rating on your radiator cap? If it's too low, it can allow the coolant to boil into the overflow bottle. Same thing if the radiator cap is worn out. Also, make sure you're running a 50/50 coolant mix so the boiling point isn't too low.

With everything as it should be, your coolant shouldn't boil until well over 260 degrees.

 

I think the issue was the nipple/breather of the reservoir was broken off and i half *** stuffed the hose onto it and looking at it now it couldn’t breath. lots of air bubbles were trapped and couldn’t escape. the way it broke off i trimmed it so it could breath better and moved on, hoping this was the fix!

 

I meant to get back to you sooner. I went to town the other day and drove back up the hill to my place; parked Blazer and noted temperature. 200 degrees went out and checked it again in about six minutes, it was about 220. I run dexcool and have replace radiator and cap. It will expand coolant and discharge it into the overflow tank, as coolant cools off and your cap is good, it will draw coolant back into the radiator. That is the purpose of the overflow tank.
The recovery tank has a level mark for full; which is down the last four or so inches. When coolant come into tank level will raise, but will be returned to the radiator when it cools down. Higher up on the recovery tank you have a vent or overflow, is this what you were speaking of, that you trimmed? If coolant gets that high that it vents, do you add more coolant? If so maybe you are overfilled. Check cap that is good, if bad fluid can't draw back into radiator.
L