It could be a head gasket, or valve trouble.
either a blown head gasket or cracked cylinder head
Blown head gasket.
you have a blown head gasket
Because you have a blown/cracked head gasket.
Bring it to your local garage
$00000000000000000.00
You must replace the defective gasket. There is no other permanent fix.
One million dollars. Dr. Evil
blown head gasket
The most likely culprit is a blown head gasket.
Bad spark plug, plug wire or both. Also burnt valve, blown head gasket, or severely worn rings. A defective intake manifold gasket is another possibility.
Check your oil. If it looks like a milkshake, the leak is internal to the engine through a cracked cylinder wall, cracked cylinder head, or blown gasket.