ArrizownEM1

I have a 99 civic si with a b16a2 in it, mostly stock besides bolt ons.
anyways a couple weeks ago it started sputtering when i start it, it sounds like a subaru when i start it and rev it but it goes back to normal after idk half a minute if that. it doesnt always do that either.

on the way to vegas the last week it started to overheat, didnt let it reach the red i turned the car off before it could get there, after that i opened the cap up and let the fluid get outta there thinking maybe there was a bubble in it. i turned the car on after it cooled down and filled it slowly adding more fluid until it was full, the drive back was about an hour and a half and the car did not overheat (this was at night) I live in Arizona where its about 115 degree weather.

anyways the overflow will fill up and the radiator wont suck it back when its cold, it hasn't overheated for the past 2 weeks ive been driving it and its just weird that it will not fill the radiator back up, i drive it about idk 25 miles a day sometimes more and when i add fluid back to the radiator its not much usually its what goes into the overflow that fits right back into the radiator perfect to the top. there is no mixing of oil or coolant, no milky ****, there is no smoke just the coolant wont go back into the damn radiator. could it be my thermostat? maybe my radiator cap?..

thanks guys!

zombiehuntr

Make sure the gasket on underside of radiator cap is good, replace thermostat ( they cheap ), and make sure engine temp sensor isn't acting up... do compression check as well......

Kron1116

Im voting on head gasket being blown. Water/oil is leaking into your cylinders when the cars off and having to burn that out when you turn it back on will make it act like its misfiring for 15-30 seconds. Considering you're missing water constantly and the car overheated is another indication. Do a compression test on all 4 cylinders and look for low numbers. After you go for a drive, remove the oil cap and look under it, if you see white murk slime, then water is mixing with your oil.

ArrizownEM1

Radiator cap looks good, i def need to replace the thermostat and yeah the temp sensor is fairly new, also itll only do that sometimes the idle thing, sometimes it wont..idk its weird and the oil cap doesnt get the slime on it at all, its pretty clean everytime i check it...