Cylinder Trouble Shooting - Stage 4

Stage 4 of the detailed cylinder troubleshooting guide

About Stage 4

Observe and record the seal condition after disassembly to determine how the seal wore and failed.

Common Seal Faults

  • Extrusion of inside diameter heel
  • Excessive abrasion or grooving of dynamic sealing lip
  • U-Cup split through centre of its cross section
  • U-Cup or piston cup is separated from heel
  • Crescent shaped section missing from dynamic sealing lip
  • Discoloration, swelling, softening or hardening of seal compound
  • Excessive wear, misshaping, darkening of V-ring set in stacked sets
  • Wear on dynamic heel 360° of seal's circumference
  • Excessive wear on dynamic heel and lip of 180° of seal's circumference.  May also show extrusion of dynamic heel 180° opposite of the worn side of the seal
  • Excessive wear on heel 360° of circumference of piston cup, often the seal lip will not show wear
  • Black, tar-like deposits and/or burned spots, possibly burned completely through the heel of the seal.  This damage will appear in the crotch area between the seal lips
  • Rolled or twisted seal may have permanent creases from twisting in seal cavity.  Maybe severely rolled
  • No viable damage, but leaking
  • Extrusion of outside diameter heel
  • Seal lips are crushed, crimped or creased
  • Seal is dark or black in colour, has lost flair or is drastically misshaped
  • Vertical/Axial scratches on static lip may be associated with other damage


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