i got a b18c1, the lower radiator hose is cold while the car overheats and the upper radiator hose is hot, but not too hot to touch, i figured it was the thermostat but i replaced that and it still overheats, any ideas? thanks

 

Flush your radiator to make sure that yu are getting good coolant flow through it.

 

some coolants will gel if you mix different types. you didn't put any orange gm coolant in your car did you? i agree your radiator might be full of poo and not working properly.

 

Also, you could simply have air bubbles in your system. A small amount of air trapped in there can stop coolant flow completely.

Before you changed the thermostat, was the cooling system opened up for any reason, like did you disconnect a hose or something?

 

air bubbles would cause a fluctuation of the temperature gauge. Meaning it'll jump up and down as air and coolant passes through the hoses and cooling the engine. Air is hotter than the water causing temp to jump and ****. unless you got all air it won't be steady.
since u already changed your thermostat....you should i guess check that radiator.

 

radiator is blocked or clogged

 

thanks for the input, i have not mixed any coolant or opened the system, i'll flush the radiator and see if that solves the problem

 

safe dude

 

You haven't opened the system? What thermostat did you change, the one on top of the radiator?

It sounds like the mechanical thermostat, the one in the block at the lower radiator hose has failed in the close position.

 

Think he meant before he replaced the thermostat.

 

Air bubbles will not necessarily cause a fluctuation where the temp will jump up and down. Air can get trapped, stopping coolant flow completely, so the car will straight overheat.

Since the OP apparently has not opened the system (before his problem and changing the thermostat), then yes, it could very well be the radiator.

 

coolant flush did the trick, thanks for the help!

 

Congrats and at least you came back and told us what fixed it. It's helpful for future people when (if) they do a search.

 

haha i'm glad you were sure to include the "if" part...most people don't search at all.