Can a Cracked Cylinder Head Be Repaired?

Big, heavy-duty diesel trucks are the backbone of industries across Canada. These beasts can run for over a million miles—if you treat them right. But even the toughest engines face wear and tear, and one of the most dreaded issues? A cracked cylinder head. It’s a problem that can stop your engine in its tracks. But can it be repaired, or is replacement the only option? Let’s dive in to find out.

Cylinder Head Basics

Your engine’s cylinder head is more than just a hefty piece of metal. It’s the lifeblood of combustion. It houses the combustion chamber, valve seats, and exhaust manifolds—all critical for your engine’s performance.

Cracks in the cylinder head can develop for several reasons: overheating, manufacturing defects, or prolonged wear and tear. While cast iron heads are tough, even they have their limits. And aluminum heads? They’re lighter but more prone to damage under extreme heat.

So, when should you repair or replace a damaged cylinder head? It all comes down to the severity of the damage and the engine’s condition.

How to Repair a Cracked Cylinder Head

The good news? Not all cracked cylinder heads mean disaster. Let’s break it down:

When Repairs Work

Minor cracks, especially in cast iron cylinder heads, can often be repaired. If the crack hasn’t spread into critical areas like the combustion chamber or valve seats, you might be in luck. For instance, cracks near exhaust manifolds or surface-level fractures are often repairable.

When Replacement is Better

If the crack compromises the integrity of the head gasket seal, or the crack spans critical areas, replacement might be the safer bet. Severe cracks in aluminum heads or advanced wear on an iron head often make repairs impractical. In such cases, a replacement cylinder head will not only save you time, it will give you the peace of mind that comes with knowing you’ve gone all out to fix the situation. This doesn’t mean your engine will last forever, but a cracked head probably won’t be an issue again. 

Steps in Repairing a Cracked Cylinder Head

Repairing cracks isn’t just a matter of filling the gap and calling it a day. Here’s a quick overview:

1. Inspection – Identify the extent of the damage using dye penetrants, magnaflux testing, or pressure tests.
2. Cleaning – Thoroughly clean the head to remove oil, grease, and debris for better repair adhesion.
3. Repair Methods – Common techniques include:
   • TIG Welding: Effective for aluminum heads, this involves welding with a filler rod to close the crack.
   • Metal Stitching: Perfect for cast iron cylinder heads, stitching uses metal pins to restore structural integrity.
   • Flame Spray Welding: A high-tech option for heavy-duty applications, this technique bonds metal to repair the crack.
4. Post-Repair Machining – Resurface and reassemble to ensure a perfect seal with the head gasket.

While DIY repairs might seem tempting, cylinder head repairs require precision tools and expertise. A poor repair can lead to recurring problems or even permanent engine damage.

To Repair or Replace?

So, can cracked heads be repaired? Absolutely—but only when the damage allows it. For heavy-duty diesel engines, professional evaluation is critical to determine the best course of action.

At Behind the 8, we specialize in top-quality diesel cylinder heads and repair advice you can count on. Whether you need help finding a replacement head or want to learn more about repair options, we’re here to help.

Explore our selection of cylinder heads, or check out our FAQs to learn more. With us, you’re always ahead of the game—no matter the challenge.