Pontiac Repair: cooling, upper radiator hose, coolant level

Question
My 1996 grand am 3.1 upper radiator hose(thermostat side) bulges when hot and collapses when cool. Is this a bad thermostat or possibly just the reservoir cap

Answer
Hi
I would suspect the thermostat first.
It will be the more diffucult to repalce though, so you may want to eliminate the Radiator cap(resivoir cap).
You may want to check coolant level, and make sure it is not low on coolant.
If not has any repairs been done lately? If so there MAY also be an air pocket in the system.
Is it running hot?
I Hope this helps.
Good Luck
Pawl