* Coolant leaks: This is the most common and relatively minor problem initially. Coolant will leak into the oil, or vice versa, or externally. You'll notice low coolant levels and potentially overheating.
* Oil leaks: Similar to coolant leaks, oil might leak into the cooling system or externally. This will lead to low oil pressure and potential engine seizure.
* Compression loss: The head gasket seals the combustion chambers. A mis-installed gasket will allow combustion gases to escape into the cooling system or crankcase. This causes significant loss of power, misfires, and eventually severe engine damage.
* Internal engine damage: The combination of coolant and oil mixing (creating a milky substance), loss of compression, and overheating can cause significant damage to engine components including pistons, cylinder walls, and bearings. This damage can range from minor scoring to complete destruction.
* Head warping: Overheating due to the coolant leak can warp the cylinder head, which requires further repairs or replacement.
In short, driving with a faulty head gasket is a gamble with potentially catastrophic consequences. It's far better to not drive the car at all until the head gasket is correctly replaced. Even a short drive can cause irreversible harm, making the repair far more extensive and costly.
