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How to Check Aluminum Heads for Cracks

by C.L. Rease

The constant change in temperature causes cracks to form in aluminum heads. Cracking causes the head to lose pressure, resulting in lost power for your vehicle. When performing your own check for cracks, you need a method of testing that does not use expensive equipment and works with a non-magnetic metal. Performing a dye penetration test makes the smallest cracks easily visible without the need for expensive equipment or a special testing facility.


Clean the aluminum head. Wipe the aluminum head with a clean rag to remove large dirt and accumulated oil. Spray cleaner-remover from a three-part dye penetrant test kit onto a clean rag. Wipe all surfaces of the head with the dampened rag.


Shake a can of penetrating dye for 30 seconds. Spray the penetrating dye on all surfaces of the aluminum head. Allow the dye to sit on the head for five minutes.


Wipe the dye from the aluminum head with a clean rag. Spray the cleaner-remover directly onto the aluminum head and immediately wipe the head with a clean rag to remove all traces of penetrating dye.


Shake a can of developer for 30 seconds. Hold the tip of the spray can 6 inches from the aluminum head. Move the spray can as you spray the developer onto the head. Allow the developer to sit for 30 seconds to one minute.


Inspect the head for cracks and pits. Look at each part of the head for lines or spots that match the dye color. A line designates a crack, and a spot designates a pit or other small imperfection on the aluminum head. No lines or spots designate an aluminum head free of defects.


Remove the developer from the aluminum head with a clean rag and the cleaner-remover supplied with the three-part dye penetrant test kit.

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