John Deere約翰迪爾強鹿柴油發(fā)動機氣缸蓋和閥門的檢查

Preliminary Cylinder Head and Valve Checks

Make preliminary inspection of cylinder head and valve

assembly during disassembly.

Look for the following conditions:

Sticking Valves:

· Carbon deposits on valve stem.

· Worn valve guides.

· Scored valve stems.

· Warped valve stems.

· Misaligned or broken valve springs.

· Worn or distorted valve seats.

· Insufficient lubrication.

Warped, Worn, or Distorted Valve Guides:

· Lack of lubrication.

· Cylinder head distortion.

· Excessive heat.

· Unevenly tightened cylinder head cap screws.

Distorted Cylinder Head and Gasket Leakage:

· Loss of cylinder head cap screw torque.

· Broken cylinder head cap screw(s).

· Overheating from low coolant level operation.

· Insufficient liner standout.

· Coolant leakage into cylinder causing hydraulic

failure of gasket.

· Leaking aftercooler.

· Cracked cylinder head.

· Cracked cylinder liner.

· Damaged or incorrect gasket.

· Overpowering or overfueling.

· Damaged cylinder head or block surfaces.

· Improper surface finish on cylinder head.

· Improperly tightened cylinder head cap screws.

· Faulty gasket installation (misaligned).

Worn or Broken Valve Seats:

· Misaligned valves.

· Distorted cylinder head.

· Carbon deposits on seats due to incomplete

combustion.

· Valve spring tension too weak.

· Excessive heat.

· Improper valve clearance.

· Improper valve timing.

· Incorrect valve or seat installed.

Burned, Pitted, Worn, or Broken Valves:

· Worn or distorted valve seats.

· Loose valve seats.

· Worn valve guides.

· Insufficient cooling.

· Cocked or broken valve springs.

· Improper engine operation.

· Improper valve train timing.

· Faulty valve rotators.

· Warped or distorted valve stems.

· “Stretched” valves due to excessive spring tension.

· Warped cylinder head.

· Bent push rods.

· Carbon build-up on valve seats.

· Rocker arm failure.

· Incorrect valve or seat installed.

· Incorrect piston-to-valve clearance.

Improper Valve Clearance:

· Inefficient use of fuel.

· Engine starts harder.

· Maximum engine power will not be achieved.

· Shorter service life of valve train.

· Greater chance for engine to overheat.

Excessive Recession:

· Worn valve guides.

· Bent valves.

· Debris passed through valve train.