Why should camshaft bearing drivers not be used on aluminum heads?

• A. They may mar the cylinder head surface
• B. They may loosen valve seats
• C. They may break the aluminum bearing supports
• D. They may crack the crankshaft

Answer: (C)

Camshaft bearing drivers can crush or crack the soft aluminum bearing supports. Aluminum heads aren’t as rigid as iron or steel, so the concentrated load from the driver can deform or fracture the bearing seats instead of correctly pressing the bearings in. This damage can misalign the cam bearings and cause oil leaks or other failures. So, avoid using camshaft bearing drivers on aluminum heads and use manufacturer-approved methods that distribute the load more safely.