alero 2000 overheating v6 3.4 no leak in the head gasket

[ihatethealero]

ok i have an alero oldsmobile 2000 v6 3.4 liters, i just replaced the thermostat and the temperature gauge, i had an overheating problem...i realized i had steam coming out of where the cap is on(on the reservoir for the coolant) so i changed it and went to have a test done to see what was wrong...so they checked it out and said there was no leak from the head gasket...but i have too much pressure building up inside the engine...i bleeded the air...flushed the radiator twice in the past month...since changing my cap 2 days ago the upper radiator hose blew up and the one right beside it a small on going on the black pipe blew up right after...i dont understand what could cause so much pressure inside the cooling systeme if its not the head gasket...can u please help i also read the error codes i got po 300,118,400,404...can someone please help before i jump out of this freakin window

[2004alero]

i had same issue mine was resolved. i replaced the thermestat 3 times no luck checked for vacume leaks ect. you might have air in your radiator line on the rail thier is a nut but i left the cap off. start the car if you see bubles then you got air in the line. let all the bubling to stop then add to your line if needed. or take nut off and get sprayed; lol. this stoped my car from over heating hope it helps you.

[2004alero]

i had same issue mine was resolved. i replaced the thermestat 3 times no luck checked for vacume leaks ect. you might have air in your radiator line on the rail thier is a nut but i left the cap off. start the car if you see bubles then you got air in the line. let all the bubling to stop then add to your line if needed. or take nut off and get sprayed; lol. this stoped my car from over heating hope it helps you.