I am having some over heating issues. Doesn't happen all the time, only on really hot days. I heard that the stock civic radiator can't handle a B18 since the GSR radiator is extra long and has higher cooling capacity. Anyone else have any issues with a stock civic radiator?

 

My stock D15 rad cools my H22 just fine, so I doubt that's your problem.

 

My stock d15 radiator cools my turboed b16 (but has trouble on the highway). Check to see if you have air in your coolant lines or possibly a bad head gasket.

 

^^ that and make sure the fins on the radiator aren't smashed for dented.

 

if you have a way of testing temps then you should check upper and lower hoses it should drop atleast 20 degrees from upper to lower. if not the radiator is bad and make sure the vehicle is at operating temp before doing this test.

 

Thanks for the suggestions everyone.