Should You Reuse Or Replace Cylinder Head Bolts? Here’s How To Know

If you’ve worked on cars long enough, there’s a good chance you’ve asked yourself whether certain parts are worth replacing or reusing. The reuse-versus-replace argument might come up often in the discussion around cylinder head bolts. 

Cylinder head bolts, as the name indicates, hold the cylinder head to the engine block (sometimes cylinder head studs are used, but it’s the same basic concept). They aren’t expensive. But a set for a Chevy LS, for example, can run between $45 and $50. So the logic behind reusing cylinder head bolts to save some money is sound. However, the catch is knowing when it’s safe to reuse them.

If your car’s manufacturer explicitly allows reuse of bolts, and if each bolt meets all the specified inspection and measurement criteria, then they might be suitable for reuse. However, even bolts that look perfectly normal may not be safe to use again. If you’re not quite sure what to do, experts recommend that you replace them.

Head bolts go through a lot of combustion pressure and thermal stress during regular engine operation. This routine strain can damage and weaken the bolts over time. Some signs that indicate your bolts may be compromised and need replacing include visible necking, distorted threads, deep corrosion, or a deformed bolt head.

Reusing cylinder head bolts that should have been replaced could prove to be a costly mistake that ruins your engine. You definitely don’t want to find coolant mixed in with engine oil or discover that the cylinder head is barely secured to the block because its bolts are no longer working as they should. Spending $50 on a new set of bolts can help you prevent expensive repairs down the road.

Cylinder head bolts are designed to last for the life of the engine but can fail prematurely due to overheating. So, to reiterate, if you aren’t sure what to do with the bolts, get a new set. But if you are more involved in the build or repair from the beginning, carefully inspect and measure each and every bolt before reusing. You might save some money and, perhaps more importantly, time in the long run (even if it’s only a quarter-mile at a time).