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Consequences of running an engine with slack Tie bolts:

  • Cylinder beam would flex and lift at the location of the slack bolt landing faces of the tie bolt upper and lower nuts, landing faces of the cylinder beam on the frame would fret and machined faces would eventually get destroyed.
  • The fitted bracing bolts between the cylinder jackets will also slacken and the fit of the bolts would be lost.
  • If fretting has occurred in an uneven pattern where the cylinder beam lands, and the tie bolts are tightened, the alignment of cylinder to the piston stroke will be destroyed. The fitted bracing bolts between the cylinder jackets will also slacken and fit of the bolts will be lost.
  • Fretting may make the nut landing face out of square and if tie bolts are tightened on the damaged face, a bending moment will be induced in the tie bolt, this may cause an uneven stress pattern in the tie bolt which could lead to early fatigue failure. Damage may take place in the bedplate in way of cross girder.                                                          
  • Rigidity of the whole structure will be destroyed. Guide force will have to be absorbed by the frame bolts and dowels, which may stretch and slacken allowing the structure to ‘work’.  This may destroy the piston alignment.   Guide faces and bars may get slackened (these are bolted to the supporting structure)

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