Loss of coolant with no apparent leak, overheating, white smoke from exhaust, foamy substance on underside of oil fill cap, oil level overfull, & air bubbles escaping from radiator.
I hate to tell you this but I just paid $3,500 at the Nissan dealer for head gasket replacment.
The only way to tell for sure is to remove the head and look. You are going to have to remove the head in either case. Remove the head and take it to a machine shop and have it inspected for cracks and to see if it is warped.
a cylinder head gasket is called in French "un joint de culasse"
A compression test will tell you if a head gasket is blown on ANY engine. Also, white smoke tells you that your burning anti-freeze, which means a head gasket is blown.
No additive is going to help - you need to get your head gasket replaced.
To tell if the head is cracked, you have to remove it from the car, so you will replace the head gasket, anyway. Take the head to a machine shop and have it magnafluxed to see if it's cracked.
Approximately $1,500 is the going rate for a head gasket replacement.
Just look at your engine oil and you can tell, if it looks milky there is water getting into the oil and that's the sign of a blown intake gasket or head gasket.
A compression test will verify if the head gasket if blown or not, the majority of the time.
You can tell if you're head gasket has been compromise by looking into the coolant reservoir, with the engine running. When the head gasket is compromised there will be air bubbles in the coolant reservoir.
Sounds like either head gasket, cracked head or cracked block
Take it to a mechanic nobody can tell you how to replace a head gasket over answers.com it requires someone who knows how to rebuild engines when a head gasket blows it requires the engine to be disassembled and rebuilt.