Symption Suspect area Remedy
Engine misfire with
abnormal internal lower
engine noises.
Worn crankshaft bearings
Loose or improperly engine filwheel
Replace the crankshaft and bearings as
required.
Repair or replace the flywheel as required.
Worn piston rings
(Oil consumption may or may not cause
the engine to misfire.)
Inspect the cylinder for a loss of compression.
Repair or replace as required.
Worn crankshaft thrust bearings
Replace the crankshaft and bearings as
required
Engine misfire with
abnormal valve train
noise.
Stuck valves.
(Carbon buidup on the valve stem)
Repair or replace as required
Excessive worn or mis-aligned timing
chain
Replace the timing chain and sprocket as
required.
Worn camshaft lobes. Replace the camshaft and valve lifters.
Engine misfire with
coolant consumption
• Faulty cylinder head gasket or other
damage to the cylinder head and
engine block cooling system.
• Coolant consumption may or may
not cause the engine to overheat.
• Inspect the cylinder head and engine block
for damage to the coolant passages and/or
a faulty head gasket.
• Repair or replace as required.
Engine misfire with
excessive oil
consumption
Worn valves, guides and/or valve stem
oil seals.
Repair or replace as required.
Worn piston rings.
(Oil consumption may or may not cause
the engine to misfire)
• Inspect the cylinder for a loss of
compression.
• Repair or replace as required.
Engine noise on startup, but only lasting a
few seconds.
Incorrect oil viscosity
• Drain the oil.
• Install the correct viscosity oil.
Worn crankshaft thrust bearing.
• Inspect the thrust bearing and crankshaft.
• Repair or replace as required.
Upper engine noise,
regardless of engine
speed.
Low oil pressure Repair or replace as required.
Broken valve spring. Replace the valve spring.
Worn or dirty valve lifters. Replace the valve lifters.
Stetched or broken timing chain and/or
damaged sprocket teeth.
Replace the timing chain and sprockets.
Worn timing chain tensioner, if
applicable.
Replace the timing chain tensioner as required.
Worn camshaft lobes.
• Inspect the camshaft lobes.
• Replace the timing camshaft and valve
lifters as required.
Worn valve guides or valve stems.
Inspect the valves and valve guides, then repair
or replace as required.
Stuck valves. (Carbon on the valve stem
or valve seat may cause the valve to
Inspect the valves and valve guides, then repair
or replace as required.