after changing intake manifolds i had refill the radiator. here are the steps i did:

topped radiator off
left cap off
let motor idle until warm and i added coolant and let all the air bubbles out (bleeding the system)

well i have done this before many times with no problems but this time i noticd the water stat to foam where the radiator cap goes. almost looked like white froth. it went away but it took it a long time.

anyone ever seen this before?

 

maybe you poured some mr. bubbles in there instead of coolant

 

hehe he said mr. bubbles

 

is your car an automatic?

 

headgasket goin..?

take off your oil cap - see if there is a white-gooey looking substance on it..