i'v changed the radiator cap but the coolent will not flow back into the radiator. when i open the cap to check coolant leval i have to pull hard on the cap, it creates a large suction. you can see the radiator upper hose has collapse some until the suction is releasted. the car is not overheating. i'm out of ideas, can anyone help?

 

I've not owned my Firebird long enough to know anything for sure, and you can discover from my posting elsewhere in this list that I have my own problems with the cooling system, but it sounds to me like something might be blocking the pipework between the engine and the coolant recovery tank.

Does the level in the coolant recovery tank go up significantly from the Cold Full mark when the engine is hot ? It should. Does a vacuum develop in the recovery tank as well when the engine cools down ? It shouldn't.

Is the small breather hole in the recovery tank cap open ?

 

i checked the vent , its ok. pulled off the tube its ok also. i cant imagine losing pressure somewhere else inside the engine faster than the coolent recovering, but i guess anything is possible.

 

If the radiator neck vent isn't plugged, it's got to be the valve in the cap. I know you said you replaced it, but check to make sure the valve isn't jammed or obstructed. It should open will very little effort.

 

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i replaced my cap as preventitive maintenance......turned out that my replacement cap was defective!