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Head gasket leak
The head gasket forms the seal between the engine block and cylinder head. If there is a leak, the compression chamber will not be sealed, allowing the fuel/air mixture to leak out and fluids such as coolant to leak in.
Table of Contents
Symptoms
Exhaust Blows White Smoke
If the head gasket has a leak, coolant may leak into the combustion chamber and ignite with the fuel. This will produce a white smoke from the exhaust.
See burning coolant.
Lack of Power
If the engine is not as powerful, some of the fuel/air mixture may be escaping through the breached seal.
Look for a misfire, if coolant is getting sucked into one or two cylinders it can cause misfires a low RPM from the coolant drowning the spark plugs.
Lack of Heat in Cabin
Coolant isn't the only thing that leaks during a head gasket leak. Combustion gases can also get pumped into the cooling system and cause it to act much like a malfunctioning thermostat. If the leak is small enough than no white smoke will be seen, but the engine will not be able to get up to operating temperature because the cooling system isn't pressurized, and air is leaking in.
Causes
Warped Cylinder Head
Over time metal can change shape depending on it's regular operating conditions. If an engine has overheated once it can be enough to warp a cylinder head enough to break the head gaskets seal.
Sometimes even higher mileage vehicles can have warped cylinder heads as the metal can warp very slowly over time from being heated up and cooled down repeatedly for so long.
Damaged Head Gasket
A blown head gasket may be the cause of the head gasket leak.
