• Stretch Bolts are used in aluminium Cylinder Heads and always need to be replaced after use.
  • The aluminium Cylinder Head will expand up to 4 times more than the older cast iron Cylinder Head. This is due to the high thermo conductive materials used within modern engines.
  • The Stretch Bolt is designed to work with the aluminium Cylinder Head unlike the older (re-usable) Bolts.
  • After use, Stretch Bolts are weakened and are not strong enough to be used again.
  • Please see the diagrams to identifying what happens when Stretch Bolts are re-used.
1  Stretch Bolt before installation.
2  Threads have become weakened after re-use.
3  Shaft has become weakened after re-use.
Head Bolts Replacement Advice
Head Bolts Replacement Advice

When removing, it is essential to follow the sequence and use the correct tool stated by the engine manufacturer in relation to the Bolt head.

  • Ensure the Bolt holes in the Cylinder Block are clear of contamination.
  • Bolts are no longer torqued to a pre-set load, a standard torque wrench is only used during pre-loading.
  • Use a degree gauge while torqueing.
  • After this the Bolts are tightened via degrees of rotation and will not be affected by the friction during loading.
Head Bolts Replacement Advice
Head Bolts Replacement Advice
Head Bolts Replacement Advice