136 4 ENGINE SYMPTOMS DIAGNOSTICS
power cylinders. The test will detect a weak
cylinder which could be the result of an injector
or base engine problem.
• Test11isusedinconjunctionwithTest
12 (Relative Compression) to distinguish
between an injector or mechanical problem.
12. Do Test 12 (Relative Compression) on
Performance Diagnostics form. This w ill verify
base engine compression.
• Test12isusedinconjunctionwithTest11
(Injector Disable) to distinguish between an
injector or mechanical problem.
13. Do Test 16 (Crankcase Pressure) on Performance
Diagnostics form. This test will determine the
condition of the power cylinders and base engine.
14. Inspect for engine and flywheel balance. Engine
roughness at idle that gets worse with a no load
acceleration may be caused by an ou t of balance
condition.
WARNING: To avoid serious personal
injury, possible death, or damage to the
engine or vehicle, support the vibration
damper during mounting bolt removal.
The damper can slide off the nose of the
crankshaft very easily.
• Following the procedure in the Engine Service
Manual remove the vibration damper and
inspect the elastomer layer for cracks and
misalignment. If no problem is found, install
vibration damper following the assembly
procedure found in the Engine Service
Manual. Verify that locating dowel on the
end of the crankshaft pulley is aligned with
locating hole in the balancer for proper
installation.
• Isolate the engin e from transmissio n by
removing the transmission, clutch and
pressure plate or torque converter. Start
the engine and evaluate for roughness. If
the engine runs smooth, replace the torque
converter or replace clutch and pressure
plate.
• Following the pro ce dure in the Engine
Service Manual, remove the flywheel and
verify proper orientation. If orientation is
correct, replace or rebalance flywheel. When
removing /installing the flywheel, ensure that
the locating dowel is in the right place and
that the flywheel is located properly on the
dowel.
• For new engines only remove t he oil pan
followingtheprocedureintheEngine
Service Manual. Inspect the crankshaft
counterweights to ensure balance holes
exist.
EGES-270-1
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
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