2000 Impala
 

I have bought a 2000 impala. With 127,000 miles on it. Any havent had any trouble with it till now. It started overheating today. When I bought it the air would only blow cold even with the heat on, the low coolant level light has been on scince i bought it. So i flushed it out twice and put all coolant in and the heater blows hot only when it wants to. Then the next day the check engine light came on. Took it to AutoZone and the code said the motor was misfiring
On cylinder #1. Then today it over heated. But when I got out to check the coolant reservoir and radiator they were NOT hot or no bubbles. I need some solutions or maybe these problems are connected.

What exactly do you mean by "all coolant"? Did you buy pre-mixed? If you bought just coolant (not pre-mixed) and didn't add any water than that could be why you are overheating. Nothing comes close to water working for heat transfer, the "coolant" that we mix in there is really just so the water doesn't freeze, help prevent boil-off (raise boiling temperature) and some additives to prevent the water from destroying everything from the inside out (think corrosion+++). If you're lucky, that misfire was due to the engine getting too hot, but not hot enough blow the head gasket or warp anything.

Heater blowing cold is a sign the water isn't making it through the heater core (bad valves?). And you can expect to change the coolant level sensor more often than the coolant (hint: you have to remove the battery, then you'll see a square object plugged into the radiator with a wire sticking out the bottom of it).

And about the water...do NOT use tap water! Buy a couple gallons of distilled or reverse osmosis water to make the mix.

What I mean by "all coolant" is that is all I put back in the radiator.Well on the coolant I says do not add water so thats why I havent. And all this did start when I put straight coolant in it. When ran with water never had the overheating problem, and after when Flushed out thr radiator and heatercore. I thought I might of ruined the spark plug or maybe the wiring getting it wet when I flushed out the heater core. When I got home last night I noticed that the radiator wasn't even hot. After I just barley made it home as it was over heating. I was able to take the cap off no problem. Even with the car reading260. The motor was very hot, even the hoses from the radiator were very stiff. But the fluids in the radiator were still cold. Like that havent even moved. So Im not getting flow or some thing. Or something sticking.

Check your thermostat to see if it locked shut.

x2 on thermostat if everything is hot but your radiator hoses/radiator are cold theres no flow getting to it