Cylinder Head Gasket Leaks – Know The Signs And Symptoms

Cylinder Head Gasket Leaks - Know The Signs And Symptoms
Cylinder Head Gasket Leaks - Know The Signs And Symptoms

Cylinder head gasket leaks, can cause a variety of problems; that no one is ready to deal with.

First of all, you can not see the cylinder head gasket; without removing the cylinder head.

So, actually finding where the, cylinder head gasket leaks are, can be difficult.

And, to make matters even worse, cylinder head gasket leaks can be, internal or external.

Cylinder Head Gasket Leaks – Know The Symptoms:

  • Compression loss, (power reduction, or a rough engine). 
  • Excessive pressure, (exhaust gases in the cooling system). 
  • Engine overheating and increased engine wear, (motor oil mixing with antifreeze).
Cylinder Head Gasket Leaks
Cylinder Head Gasket Leaks

So, usually one of these symptoms by itself; is not enough to prove you have, cylinder head gasket leaks. But, having multiple symptoms at the same time; increases your chances dramatically. That’s why, knowing the signs can steer you in the right direction.

So, besides allowing coolant into the combustion chamber; an internal head gasket leak allows, exhaust gases into the coolant. As a result, this can cause bubbles that make the coolant look like it’s boiling; even when it’s cold.

Consequently, the bubbles are exhaust gases; that force their way into the cooling system, during the combustion process.

Air Bubbles In Radiator
Air Bubbles In Radiator

Furthermore, antifreeze in the crankcase, can also dilute and contaminate the engine oil. So, with little to no lubrication the first thing to wear out, are the engine bearings. Along with this, you could hear, lifter ticking noise.

NOTE: An internal coolant leak doesn’t always mean the head gasket is leaking. Because, hairline cracks in the cylinder head or engine block, can also cause leaks.

One method for finding a leaky head gasket is to do, a pressure test. Start by, removing the spark plug from the cylinder that is misfiring and; apply air pressure to the cylinder. Consequently, if the air leaks into the cooling system, the head gasket is leaking.

Above all, it is important to drive your vehicle as little as possible; if you have cylinder head gasket leaks.

Cylinder Head Gasket Leaks
Cylinder Head Gasket Leaks

Symptoms Of Cylinder Head Gasket Leaks:

  • Coolant leaking externally, from below the exhaust manifold
  • White smoke, from the exhaust pipe
  • Overheating engine
  • Bubbles in the radiator or coolant overflow tank
  • White milky oil
  • Significant loss of coolant, with no visible leaks

Hot gases and cold coolant moving past the gasket can quickly warp the cylinder head or engine block. As a result, leaving you with costly machining bills or even having to purchase; new heads or a new engine.

Catalytic Converter Damage

Catalytic Converter Damage
Catalytic Converter Damage

Antifreeze entering the exhaust system, can block the air passages; by creating heavy carbon deposits that coat the ceramic catalyst. These heavy carbon deposits create, two problems. First, the carbon deposits prevent the catalytic converter from; reducing harmful emission in the exhaust flow. And second, the carbon deposits clog the pores in the ceramic catalyst and, block exhaust flow. As a result, increasing back pressure and causing heat and exhaust to back up, into the engine compartment.

If a large amount of coolant leaks, hydro lock can occur, causing extensive engine damage.

Cylinder Head Gaskets Seal, Three Different Types Of Fluids:

  • Combustible air/fuel mixture
  • Water based coolants
  • Motor oil for lubrication
External Cylinder Head Gasket Leaks
External Cylinder Head Gasket Leaks

Apart from sealing the cylinder, the head gasket also seals, water and oil passages; between the head and block. So, any leaks between them, will cause engine failure or significant problems like, burning oil. As a result, blue exhaust smoke may be indicative of, oil burning. While, white exhaust smoke is an indicator of coolant burning, another sign of, head gasket leaks.

White Exhaust Smoke
White Exhaust Smoke

Occasionally, the compression in the cylinder will cause, a leak to form in the head gasket. But, this problem has been magnified by the use of aluminum. Because, aluminum has a much greater thermal expansion rate than cast iron. Engine makers have responded to this by adding a non-stick coating; such as teflon to the surface of the gasket. Finally, this allows the head to slide on the block, causing less damage to the gasket.

Sometimes, all you see is, excessive white smoke out the exhaust. But, the engine may run and drive like normal. However, the engine will overheat, when all the coolant is gone.


So, the main cause for, cylinder head gasket leaks is, extreme engine temperature. That’s why, a coolant leak or just not having enough coolant can cause, overheating. However, because of the different material combinations in today’s engines; head gaskets are going to fail. Finally, when they do, have the repairs done, as soon as possible; to avoid further damage.

Thank You !