Overheating

[darkthoughts5000]

For some reason my car is overheating. I changed the thermostsat and the problem still persists. After driving for about 20-25 minutes is fine, but if I have extended errands, the tempature fluctuates (spelling?) from the stopping and going. It will get to 210 degrees and then almost up to the 260 mark! the engine had roughly 60,000 miles (not completely sure as I replaced the engine about 2 years ago and the junk yard said it had about 50,000 miles. I have checked and re-checked the hoses and no leak exisits. What could this be? Also, even if the car reaches 210 degrees, the heater still blows cold. I turned on my heater yesterday and I was a little confussed to find that the heater was blowing cold air. Please help.

[FunkZ]

If the heater is blowing cold, then no coolant is reaching the heater core. Now, this could be a seperate problem, but very likely the two are related.

Check your coolant level in the radiator, wait until it cools down of course. If there's plenty of coolant then the other things it might be are water pump or a blockage in the line somewhere.

[BLLDOGG]

Heater core: With the engine running, feel both heater hoses with the heater set to max. both hoses should be too hot to hold. if both hoses are warm, not hot, or cool, cheack the heater control valve for proper operation. if one hose is hot and the other return hose is just warm or cool, remove both hoses from the heater core or engine and flush the heater core with water from a garden hose.

check and make sure your hose from the radiator to the thermo is pressurized and hot.

[kahouna23]

Kinda funny someone would mention the fluctuation on the temp gauge. I noticed today in stopped traffic that my temp gauge was doing the exact thing. As soon as I started moving, the gauge went back to normal temp indication. I'm guessing that there is some sort of sending unit for the gauge, but I have no idea where it gets that indication from. Where is the temp sensor? On the radiator, heater core...???

[BLLDOGG]

usually during an over heating problem during stop and go, it a problem with air flow. so check if the fans work and check for anything blocking the radiator. i would just go ahead and clean it. run water from the engine side out to clean the radiator.

[darkthoughts5000]

Thanks guys. I'll be doing some checking on the radiator this weekend. Hopefully it isn't anything totally F-ed up. I appreciate your help.

[green97]

I just had this problem last week, I changed the thermostat and everything seemed fine, but about 5 hours later I noticed coolant coming out from the bottom of my water pump. Replaced water pump and everything is fine now.

[CAMAROWIDBASS]

remove your radiator cover, sometimes plastic bags get stuck in there and dont let air flow through.

[rallysportchic97]

I had the same problem with mine for months. Turned out I had a leaky head gasket and a hairline crack in my manifold. My heater was blowing cold too. At first I thought I had a coolant leak or a clog and had it flushed twice and looked at several times. Eventually, I ended up getting a new engine cuz by the time we figured out the real problem, other things were wrong and I had no other option.