Coolant question
 

Hey everyone just a quick question and I may be overthinking this but long story short i did a coolant flush and when i refilled my coolant i had only bought 2 gallons for my sierra 1500 4.8. It was short of filling the reserve tank about half way and when i start my truck and check the reserve its empty except for a tiny bit right at the neck of the reserve entering the hose. Now i knew i needed more but had to drive the truck to go get more which was close to an hour drive. Engine temp stayed normal only once going 5 degrees over 210 and no lights turned on. Do you think I did any damage to my engine by doing this?

how much more were you low? but generally speaking engines are safe imo around 230 (in an emergency). but i wouldnt want run there as it means something in the coolant system isnt working right

Seems like half the reserve tank which was a little more than a quarter of a gallon

Did you fill the radiator?

Hey joe, so im not much of a mechanic but i had to replace my thermostat and sensor which is why im going thru this atm, so i didnt think the radiator also gets flushed when replacing these, so to answer your question no i did not

Doesnt the radiator fill from the same tank? Or is it seperate, sorry for the stupid questions

on some vehicles you can only fill through the overflow tank. if theres a cap on the rad then you fill it through there. but you can have air trapped in the system. i know on my impala theres a bleeder valve on the thermostat housing not sure about the 4.8 though

Yes the system will draw some coolant in from the reservoir when you shut off the engine and it starts to cool off, but it takes time. It also depends a lot on the design of the system. They have changed over the years, and I have no idea what vehicle this is or how you did your flush.

The bottom line is the reservoir isn't nearly as important as the radiator itself since that's where fluid enters the pump. If the system had a bunch of air, the temp sensor won't report accurately, and the engine could indeed be overheating.

So how much more coolant did the truck end up needing?

Looks like it only needed about a quarter of a gallon maybe a little more so im gusssing at first the coolant was at where it needed to be but nothing for the system to pull from until i added more. So 2.5ish gallons of coolant for a 2009 sierra 1500 4.8 if that sounds right

I don't think 1 qt low would do any damage.