How to Check a Cylinder Head for Straightness

A cracked, damaged or warped cylinder head can take any vehicle off the road. Whether due to incorrect maintenance, repairs, or even production and manufacturing issues (no manufacturer is immune, as the latest BMW recall shows), a warped or cracked cylinder head needs to be addressed immediately. 

In this guide, we’ll cover the signs of cylinder head problems, how to check a cylinder head for straightness, and why sourcing top-quality parts from BehindThe8 is key to keeping your heavy-duty engine running strong.

Signs Your Cylinder Head Might Be Warped

Not every engine issue screams “cylinder head problem,” but a few telltale signs can help narrow it down:

1. Loss of Compression: If your engine struggles to generate power, it could mean the cylinder head isn’t sealing properly against the engine block.
2. Coolant or Oil Leaks: A faulty seal can let coolant or oil seep past the head gasket, causing overheating or contamination.
3. White Smoke from Exhaust: Coolant entering the combustion chamber often leads to white exhaust smoke—a sign something’s amiss in the mating surfaces.
4. Overheating: Heat warps aluminum cylinder heads quickly. If your engine is running hot, it’s worth investigating.

While these symptoms aren’t definitive proof of a warped head, they’re solid indicators to dig deeper.

How to Properly Inspect and Test a Cylinder Head for Straightness

Checking a cylinder head for straightness requires the right tools and attention to detail. Here’s how to do it like a pro:

1. Prepare the Cylinder Head
   Remove the cylinder head carefully, following the proper sequence for head bolts to avoid further warping. Once removed, clean the surface thoroughly to remove any debris, gasket material, or oil.
2. Inspect for Visible Damage
   Before using tools, visually inspect the cylinder head surface for cracks, pits, or other signs of damage, especially around the combustion chambers and bolt holes.
3. Use a Straight Edge and Feeler Gauge
   Lay a precision straight edge across the cylinder head in multiple directions—lengthwise, crosswise, and diagonally. Insert a feeler gauge under the straight edge to check for gaps. Most cylinder heads allow a maximum of 0.002–0.004 inches of warpage; anything beyond that indicates it won’t seal properly.
4. Focus on High-Stress Areas
   Pay extra attention to areas near the combustion chambers, as these spots experience the most heat and pressure.
5. Determine Next Steps
   If the warpage exceeds specifications or the surface shows signs of damage, the cylinder head may need to be resurfaced or replaced. In such cases, sourcing a high-quality replacement is critical to restoring proper function.

Why Choose Behind the 8 for Cylinder Heads and Engine Parts

At Behind the 8, we know that the right parts make all the difference in heavy-duty engine performance. That’s why we focus on providing top-tier replacement components, from cylinder heads to gaskets and beyond. With over 25 years of industry experience, we’re proud to supply the parts that keep your engines running strong, whether you’re maintaining a single truck or an entire fleet.

When it’s time to replace a warped or damaged cylinder head, you’ll find options tailored to heavy-duty diesel applications, backed by exceptional quality standards. Need more information about our products? Our FAQs offer quick answers, or you can reach out to us directly through our contact page.

Taking the time to inspect your cylinder head for straightness can save you from bigger problems down the road. And when it’s time to replace, Behind the 8 is here with the parts and expertise you need to get the job done right. Don’t compromise—choose quality, choose BehindThe8.