well i have a 91 crx si w/b16 and last week i blew the coolant hose that loops/connects to the intake manifold. so i replaced it thinking it was all good. well when i got her home the coolant was overflowing in to the overflow reservoir to the point i thought that it was going to explode out. i was thinking that maybe the radiator cap was bad bc of how much it would move, so i replaced it and its still doing the same thing but worst now. the car was NOT overheating at all until i replaced the radiator cap. what else could i check. im thinking that their has to be some sort of blockage somewhere bc the coolant dose not start overflowing until 15-20 min after the car is warmed up. im going to replace the thermostat to see if that helps but i just wanna check if anybody has some other ideas.....thanks

 

I had a civic that did the same thing once. Went through everything and couldn't get it straightened out. Ended up being a slightly blown headgasket between the cyl and the water jacket. Car never overheated, and no water ever got in the oil.

Replaced HG, and all was good.

 

blown headgasket or cracked head.