i got a b18b1 in my hatch and when im cruising on the interstate at 75-80 the temp guage will start to go up and i have to slow down to 60 and it will go back down. Will a better radiator help this problem.

 

You have a bad temp. gauge

 

my friend had a problem like this on a similar swap. He had opted to keep his half-sized radiator from the civic shell he was working on and put in a b-series integra motor. When he switched to the full sized radiator from an integra (which I believe he had to custom fit in unless I'm mistaken), it actually fixed his problem. I don't know if you are having the same problem or if you gauge is just broken, but it's a thought.

 

make sure that your cooling fan is coming on...and that your ride isn't leaking antifreeze from anywhere..
good luck..

 

If your over heating while driving you have air in your radiator. Take your radiator cap off and turn you heat on at full blast till your car is fully warmed up. This should get most of the air that is trapped in. It will over flow but that is normal. Also you should have a bleeder screw on your head next to the upper radiator hose.

 

Also could just be a bad cap...Seen it before...But yeah air will do it too...Burp it.

 

i agree also either air in system or bad cap..let car cool before opening cap of course and then as said before run car with heat on full until at full temp just add coolant as needed.some advise i use a stock cv boot put it in the neck of rad and fill it with coolant/water to force bleed.hope this helps