If the repair was recent, there could still be air trapped in system and this can result in high pressure than normal. When engine is cold, remove radiator cap and check the coolant level in it. Top up if necessary.
Next to check would be the radiator cap. A bad cap would not be able to hold the pressure and allow coolant to be pushed to the reservoir.
If above 2 are found to be good, I am afraid you could still be having a problem with the head gaskets. Pressure is escaping from cylinders into the coolig system and it could also be due to a bad cylinder head or the block surface is not level.
If the upper radiator hose is too soft, you would need to replace it. This can be due to the quality or age/condition of the hose.
Do you still have coolant losses and overheating issues, which yuou have not mentioned?
Sunday, October 7th, 2012 AT 5:57 PM