GMC Yukon 2000–2006

▸ENGINE1

1. Manufacturer communication2000–2006 GMC YUKON DENALI ・ 2017-08-15(1 earlier editions of this document folded here)

   Engine Block Cylinder Bore Damage Preliminary Information

   1. 1Fault

      • Leak
      • Misfire or rough idle
      • The engine block is suspected of cylinder bore damage, scoring or out-of-round as the cause of oil consumption, misfire, cylinder leakage or blow-by.
      ↓→

   2. 2Finding the cause

      • Cylinder Bore: worn

      Possible causes

      • With dirt intrusion through a compromised air filtering system the engine wears out very quickly: grit is found in the intake runners and the bores look lightly sandblasted.
      • If a catalytic converter fails and its brick breaks, the dust can be drawn back into the engine, and the bores look sandblasted.

      Steps to confirm (in the document’s order)

      1. Cylinder damage or scoring shows as grooves in the cylinder wall deep enough to catch with a fingernail.
      2. An out-of-round bore has areas where the crosshatch is missing or worn; if crosshatch runs all the way around the bore from top to bottom, the bore is not out of round.
      ↓→

   3. 3Correction

      Repair

      • With converter dust the back cylinders are affected first if caught early; otherwise no crosshatch remains and the engine must be replaced.

      Caution

      • GM states it has had no issue with cylinders machined out of round in any engine family in recent history.
   Read the sentences of the record

   From the manufacturer’s document

   • Applies to：Applies to 2017 and prior GM passenger cars and trucks.
   • Condition：The engine block is suspected of cylinder bore damage, scoring or out-of-round as the cause of oil consumption, misfire, cylinder leakage or blow-by.
   • Caution：GM states it has had no issue with cylinders machined out of round in any engine family in recent history.
   • Confirm：Cylinder damage or scoring shows as grooves in the cylinder wall deep enough to catch with a fingernail.
   • Confirm：An out-of-round bore has areas where the crosshatch is missing or worn; if crosshatch runs all the way around the bore from top to bottom, the bore is not out of round.
   • Cause：With dirt intrusion through a compromised air filtering system the engine wears out very quickly: grit is found in the intake runners and the bores look lightly sandblasted.
   • Cause：If a catalytic converter fails and its brick breaks, the dust can be drawn back into the engine, and the bores look sandblasted.
   • Repair：With converter dust the back cylinders are affected first if caught early; otherwise no crosshatch remains and the engine must be replaced.

   Open the manufacturer’s document (PDF) ↗ The points above were read from this document.

   Remedy

   This Preliminary Information communication provides information to the technician about engine block that have a possible cylinder bore damage, scoring or out of round as the possible cause of engine oil consumption, misfire, cylinder leakage or blow by. Technician will need to inspect the engine for Cylinder damage or scoring, an out of round cylinder bore, Dirt intrusion, and Catalytic Converter failure.