My 03 Civic is still overheating after replacing the thermostat and the radiator. There is a crack in the exhaust manifold but not big enough to be letting that much heat in. I have read that there is air in the cooling system that can be let out by bleeding the system, which I don't know how to do. I have also read that it could be a blown head gasket. I do need a new valve cover gasket but didn't think it would be what's causing it to overheat still. The day I replaced the thermostat, the air conditioner was immediately cold and hadn't been that way for a while now. It's not as cold as it was but it has been close to 90 here lately. If anyone has any ideas about what it could be, please let me know! Thanks in advance!

 

most likely its the head gasket.

 

welcome to the forum. Did you check to see if the elec fan is working? I believe you have 2 fans, one for the a/c, and one for the normal cooling of the radiator.

 

I was so hoping it wasn't the head gasket lol. Thanks! I'll check it out.

 

Yes, I have 2 and as far as I know the one cooling the engine comes on when it's supposed to but I'm not totally convinced. I sat at home yesterday for a little bit after driving it to see if both were running and if it would overheat, and they were and it never got hot. But when sitting in the drive thru at the bank or in a parking lot, it does get hot and I don't get the chance to see if the one is running.

 

If the overflow tank empties slowly, when the engine cools down, the radiator cap may be bad. By increasing pressure, radiator caps allow the coolant temperature to be about 30 degrees higher than it would otherwise. Additionally, they have two valves in them. One allows the hot coolant to flow into the overflow tank. The other opens and allows the coolant to flow back into the engine, when it cools down. Go with an OEM replacement, if you suspect this could be the problem. or
If the pump was changed then like others said all signs lead to the head gasket. If you have fluid coming out of your resivoir, im sorry to say, but its the head gasket. The reason being is, you have cylinder pressure being forced into your cooling system and with all that air, it displaces the coolant. The only place it can go is out your resivoir cap. It is a fairly easy job if ya got the tools and the common sense. Good luck man!!!

 

you can take it to advance auto or pep boys and they will test it for free regarding the headgaskit. they test the fluids.

 

hold on a sec, you need to get your but out of the drivers seat and check to see if your fan engine fan is coming on or not. Let the car idle in the driveway for 10 mins., with the A/C off and visually look and see if the engine fan comes on when it gets wormed up, if it does not, replace the coolant temp/fan switch.

 

did you change the rad and thermostat yourself? if so, you could be overheating because you didnt bleed the system and have air inside. from your post you don't know how. well, a good way to tell if you have air in the cooling system after your repair is to see if your heater blows hot. to bleed a cooling system, turn your heater to hot, leave your rad cap off and just run the engine.

 

If you hear a ticking from under the hood it's def the head gasket.