Head gasket job on a 2007 Chevy 5.3 LS.

The problem is reusing the head bolts. GM's 5.3L LS uses torque-to-yield (TTY) head bolts (confirmed by GM service manual and ARP's application guide). These bolts are designed to stretch permanently during installation and must be replaced, not reused.

When you clean and reuse TTY bolts, the threads may look fine, but the bolt material has already yielded. Re-torquing them to 22 ft-lb + 90° won't achieve proper clamping force because the bolt can't stretch the same way again. This leads to uneven head gasket sealing, potential warping, or blowouts.

Correct procedure:

1. Replace all head bolts with new GM OEM or equivalent (ARP part #234-4301 or GM 12571231).
2. Clean block threads thoroughly with a thread chaser (not a wire wheel, which can alter thread geometry).
3. Apply engine oil to threads and under bolt head.
4. Torque to 22 ft-lb, then turn an additional 90° in two 45° steps.

The wire wheel cleaning isn't the primary issue—it's the reuse. Even if threads look clean, the bolt's mechanical properties are compromised after one use. Replace them.

You're reusing torque-to-yield (TTY) bolts. That's the failure point.

The Code/Engineering Spec: GM Service Information (and the bolt head marking) identifies these as TTY (Torque-to-Yield) fasteners. The 22 ft-lb + 90° + 90° sequence permanently stretches the bolt into its plastic deformation zone to achieve precise, consistent clamp load.

Why your process fails:

1. Wire wheel: Removes the phosphate coating and damages thread geometry, altering friction coefficients. The torque-angle spec assumes original surface finish.
2. Oiling threads: Further reduces friction unpredictably. The spec is calibrated for dry, original threads (or specific GM thread sealant on lower bolts). Lubrication causes over-stretch at the same angle.
3. Reuse: A stretched bolt has no elastic reserve left. It cannot maintain clamp load through thermal cycles. It will yield further or fracture.

The Fix: Buy new OEM head bolts (GM 12580681 or equivalent AC Delco). Do not use aftermarket "performance" bolts unless switching to studs (which requires align-honing the block).

Correct Install:

1. Chase block holes with a bottoming tap (clean threads, don't cut new ones). Blow out with compressed air.
2. Do not oil threads. Install bolts dry into the block (lower bolts may require GM Thread Sealant #12346004 per TSB).
3. Torque sequence: 22 ft-lb → 90° → 90° (using angle gauge, not "feel").

Cost of error: Blown head gasket (again), warped heads, or bolt failure destroying the block. New bolts are ~$40. Don't gamble a $2,000 job on used hardware.