6-14
ENGINE DIAGNOSIS
Condition
Possible Cause
Reference Item
Excessive engine oil
consumption
Oil entering combustion chamber
Sticky piston ring
Worn piston and cylinder
Worn piston ring groove and ring
Improper location of piston ring gap
Worn or damaged valve stem seal
Worn valve stem
Piston cleaning in Section 6A or 6A1.
Cylinders, pistons and piston rings
inspection in Section 6A or 6A1.
Pistons and piston rings inspection in Sec-
tion 6A or 6A1.
Pistons installation in Section 6A or 6A1.
Valves and cylinder head in Section 6A
or 6A1.
Valves inspection in Section 6A or 6A1.
Low oil pressure
Improper oil viscosity
Malfunctioning oil pressure switch
Clogged oil strainer
Functional deterioration of oil pump
Worn oil pump relief valve
Excessive clearance in various sliding
parts
Engine oil and oil filter change in
Section 0B.
Oil pressure switch inspection in
Section 8.
Oil pan and oil pump strainer
cleaning in Section 6A or 6A1.
Oil pump in Section 6A or 6A1.
Oil pump in Section 6A or 6A1.
Engine noise
Note: Before check-
ing the mechanical
noise, make sure
that:
Ignition timing is
properly adjusted.
Specified spark
plug is used.
Specified fuel is
used.
Valve noise
Improper valve lash
Worn valve stem and guide
Weak or broken valve spring
Warped or bent valve
Loose camshaft housing bolts
Piston, ring and cylinder noise
Worn piston, ring and cylinder bore
Connecting rod noise
Worn crankpin bearing
Worn crankpin
Loose connecting rod nuts
Low oil pressure
Crankshaft noise
Low oil pressure
Worn crankshaft journal bearing
Worn crankshaft journal
Loose lower crankcase
(bearing cap) bolts
Excessive crankshaft thrust play
Valve lash in Section 6A or 6A1.
Valves inspection in Section 6A or 6A1.
Valve springs inspection in Section 6A or
6A1.
Valves inspection in Section 6A or 6A1.
Camshafts in Section 6A or 6A1.
Pistons and cylinders inspection in Sec-
tion 6A or 6A1.
Crankpin and connecting rod bearing in-
spection in Section 6A or 6A1.
Crankpin and connecting rod bearing in-
spection in Section 6A or 6A1.
Connecting rod installation in Section 6A
or 6A1.
Previously outlined.
Previously outlined.
Crankshaft and bearing inspection in
Section 6A or 6A1.
Crankshaft and bearing inspection in
Section 6A or 6A1.
Crankshaft installation in Section 6A or
6A1.
Crankshaft inspection in Section 6A or
6A1.