bad/blown Head Gasket Symptoms 6.4 Powerstroke (fix guide)

The head gasket in 6.4 Powerstroke is a multilayered steel component that seals between the cylinder head and the engine block. If it fails, oil and coolant may contaminate each other, or combustion gas may escape.

A leaky head gasket is an unlucky time for a 6.4 Powerstroke owner. Besides leaking, a failed head gasket can shout to you with some more warning signs. The most common ones include bubbling, different smokes (gray/blue, sweet-smelling, white), milky oil, overheating engine, poor performance, coolant leak, etc.

In this article, we will look at the 6.4 Powerstroke head gasket symptoms with their possible explanation, causes, and how to address them.  Stay tuned!

common Head Gasket Symptoms 6.4 Powerstroke (fix guide)

What Does a Head Gasket Do in Your 6.4 Powerstroke?

A head gasket is a piece of material that seals between the engine block and cylinder head. It is used in an internal combustion engine as a closing door to seal the combustion gases within the cylinder. Therefore, it prevents coolant or engine oil from leaking into the cylinders.

An engine can operate successfully as long as the head gasket prevents the leak of the following circuits;

  • Combustion gases
  • Coolant
  • Lubricating oil

Ignition of fuel generates pressure, and the head gasket ensures this pressure remains inside the combustion chamber.

A head gasket comprises many layers of steel. This construction makes them durable. However, if the head gasket fails, your engine is prone to severe damage.

8 most common Causes of 6.4 Powerstroke Head Gasket Symptoms

Though 6.0L is among the most unfortunate for head gasket failure, 6.4 is not far behind. And that applies to every diesel engine operating at high temperatures and high combustion pressure. Therefore, issues like overheating and pre-ignition can be accused of gasket failure. 

Concerning the 6.4L Powerstroke, the failure of its head gasket is caused by its special cooling system. On the other hand, the main reason the 6.0L failed was an oil cooler malfunction.

Early SymptomsLate Symptoms
Bubbling in the radiator and coolant reservoirOverheating engine
Sweet-smelling smokePoor performance
Grey-blue smokeMilky oil
White exhaust smokeOdor inside the cab
Coolant leak
Unexplained coolant loss with no leak

The following describes how these symptoms develop over time:

#1- Bubbling in the radiator and coolant reservoir

Bubbling means air pressure is rising inside the cooling system. This happens when the flow of liquid is blocked by some air. In a blown head gasket, the air pressure inside the cylinder is transferred to the cooling system. Now, the free air creates bubbling. This is one of the telltale signs of head gasket failure.

#2- Sweet-smelling smoke

A blown head gasket can lead to coolant leaking into cylinders. If this happens, you will experience a sweet smell like burnt sugar. Consequently, this leakage may cause engine overheating.

#3- Grey-Blue Smoke

Blue smoke leaking out from the exhaust reveals oil penetrating the cylinders. The cause remains the same- head gasket failure.

#4- White Exhaust Smoke

While smoke may indicate several damages, white smoke coming from your exhaust is probably because coolant is leaking into cylinders. Coolant is then burned, producing this characteristic of smoke.

If there is a breach in the head gasket, coolant may leak and create this type of white smog. Take care of the breach; otherwise, it may get bigger and bigger.

#5- Overheating Engine

One of the most typical sign of a failing head gasket is continuously overheating engines. The car loses coolant when a head gasket blows, and it might leak into the cylinder. Gases could also seep into the coolant. Again, producing power requires more effort from engines. These two elements keep the temperature of the engine rising.

If you continue to drive your car at this point, you risk harming both the cylinder head and the engine. However, a blown head gasket is not the only culprit behind engine overheating. Several reasons (e.g. Restricted radiator) may also show this symptom.

#6- Milky Oil

Another ridiculous way to recognize head gasket failure is the presence of milky oil. Your 6-year-old son may feel happy to see that your ford Powerstroke is also fond of chocolate milkshakes.

If there is a breach in the gasket, the oil may contaminate the coolant. As a result, it will look like milky sludge. You may suddenly discover this yummy juice while you’re checking the oil or changing it.

#7- Poor Performance: Loss of Power/Starting/Rough idling noise

If the head gasket fails, the combustion chamber is no longer completely sealed. So, fuel and air combustion are not adequate. Outcomes will be rough idling noise; a sound mimics an exhaust leak. And a notable reduction in the engine power.

However, poor performance can be caused by some other reasons too. A compression leak test may recognize whether the lesion is in the head gasket or not. Unfortunately, you need some instruments to perform this test. To wrap up, if combustion gasses are mixed with the engine oil, it implies your head gasket failed somewhere.

#8- Unevenly clean spark plugs

If you notice that one spark plug is visibly cleaner than the other, it indicates coolant is leaking into that cylinder. No wonder gasket failure is the culprit here too.

How to Deal with Head Gasket Failure in 6.4 Powerstroke?

As soon as you diagnose head gasket failure, stop driving as early as possible. Driving with a blown head gasket may lead to severe damage to the engine. And you must repair it properly as recurrence is common. Follow these steps to replace a blown head gasket.

  • Remove the cylinder head along with the old blown gasket
  • Clean the cylinder head and cylinder block mating surfaces
  • Flush the cooling system to remove any gunge that can cause a blockage
  • Check the cylinder head for any visible distortion
  • You may skim the mating surface to ensure that it is flat
  • Now, it’s ready to replace with a new head gasket

HOW TO REPLACE HEAD GASKETS ON 6.4 POWERSTROKE (Part 1: Removal) >> Check out the video below:

How to Prevent Head Gasket Failure?

We recommend you keep the coolant at the proper level with the correct mixture to prevent this devastating situation. Plus, don’t let the temperature gauze run hot. And any coolant leak must be checked carefully.

Final Words

Hope this article has shed some in-depth info about 6.4 Powerstroke head gasket symptoms. Head gasket failure itself doesn’t render a car undrivable.

But it leads to severe damage to critical parts, so early recognition and repair are crucial.

Want more articles like this? Here are other 6.4 powerstroke related articles you might like:

5 Common 6.4 Powerstroke EBP Sensor Symptoms (With Solutions)

4 Common IPR Sensor Failure Symptoms On 6.4 Powerstroke

Who Worked on This post?



Anderson is an experienced auto mechanic with over 10 years in the industry. He is skilled in diagnosing and repairing a wide range of vehicles, from sedans to trucks and SUV

Syed Ahmed


Syed Ahmed has been working as an auto mechanic editor for the past five years. He has a background in mechanical engineering and a love for all things automotive

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