Cylinder head bolts are always tightened from the center outward in a spiral pattern. This ensures the gasket seats evenly and the head does not warp or crack.

View the engine from the front (timing cover side): Start with the center bolt row. Progress spiraling clockwise: Center top -> Center bottom -> Left bottom -> Left top and so on, until you reach the outermost bolts.

Tightening is usually done in three stages: Stage 1: 20–30 Nm (installation torque for all bolts in sequence). Stage 2: Angle tightening (for example, 50°±4°). In this stage, a degree wheel or careful visual estimation is used. Stage 3 (Re-torque): * Run the engine to warm it up (approximately 30 min). Let the engine cool thoroughly (at least 2.5 hours). Tighten the bolts again with a final angle, for example 120 degrees.

The need for re-torque depends entirely on the gasket type used: Traditional soft metal gasket (Soft): Requires re-torque in almost all cases (Stage 3) because the gasket "settles" during the heat cycle. Steel multi-layer gasket (MLS / Multi-Layer Steel): * NO re-torque. With steel gaskets, a "tighten once" method is usually used (for example, 20Nm + 60Nm + 90° angle). Always check the instruction sheet (for example, from Elring or Reinz) that comes with the gasket!

Bolt condition: Many modern head bolts are so-called stretch bolts. They are designed to be used only once. If a bolt has stretched beyond the allowed measurement, it will break when tightened or fail to hold torque. Recommendation: Always use new bolts. Clean threads: Make sure the bolt holes in the block are completely clean of oil and water. If there is liquid in the hole, tightening the bolt creates hydraulic pressure that can crack the block. Lubrication: Apply a thin layer of engine oil to the bolt threads and under the head to reduce friction during tightening (unless instructions say otherwise).

If you use angle tightening, draw a line on the bolt head and the head with a marker before turning. This way you can see at a glance which bolts have already been turned and how much.