HouseCallAuto 9/17/2012If you have white smoke which is the result of coolant leaking in from a bad head gasket, you will not see any external leakage around the head. One thing you will notice is that your coolant is disappearing. A check engine light does not have to set. Sometimes when you start the car up cold if you notice it runs rough for a minute and then clears up, that is usually a sign of coolant leaking into a cylinder.
HouseCallAuto 9/19/2012Deciding to replace a head gasket is a repair that should only be done when there is enough convincing evidence. If you are losing coolant regularly and constantly topping it off with a quarts or two regularly and you see white smoke out the exhaust, smoke that YOU DID NOT USED TO SEE LIKE THIS, then yes, pull the head and investigate and hopefully you will find a bad gasket. If you are also sure that there are no external coolant leaks, meaning that you have pressure checked the system when overnight cold using a cooling system pressure tester and while the system was under like 15 lbs of pressure you saw no drips from anyplace external and upon examination visually in a patient manner you looked at all cooling system hoses and connections and whatever gaskets are viewable at all places externally, then yes go at the head gasket. if you are not losing coolant and you are not overheating, don't rush to head gasket judgement.