How to Check for Warped Cylinder Heads (2024)

For your engine to operate smoothly, efficiently and leak-free, the cylinder head must mate to the engine block properly. A warped head could cause oil and coolant to leak out of the engine or into adjacent cylinders, causing your engine to smoke. A warped cylinder head could also decrease performance, because the air and fuel compressed in the cylinder could flow out of the engine or into other cylinders.

Set the cylinder head on a large work surface.

Place a straightedge on the cylinder head diagonally from corner to corner.

Set your feeler gauge at .003 inch, and place the gauge between the straightedge and the cylinder head. If the feeler gauge fits in the gap, then your cylinder head is warped and must be machined flat.

Set the straightedge at the other corners diagonally, and check the gap with the feeler gauge. If the gauge fits between the head and the straightedge, the cylinder head must machined flat before going back into service.