GMC chevrolet camaro 2000 Service Manual page 789

6-22 Engine Mechanical - 3~8L
Engine
Checks
Oil Consumption
Abnormal Internal Engine Noises
No Abnormal Internal Engine Noise
Base Engine Misfire Diagnosis (cont'd)
Action
O.il consumption may or may not cause the engine to misfire.
1.. Remove the spark plugs and inspect for an oil fouled spark plug.
2. Perform a cylinder compression test.
3. If the compression test indicates worn valves or valve guides, inspect the
following:
O
Worn, brittle, or improperly installed valve stem oil seals
• Worn valve guides
• Worn valve stems
• Worn or burnt valves or valve seats
4.' If the compr,ession test indicates worn or damaged piston rings, inspect the
following: · ·
0
.Broken or improperly seated piston rings
• Excessive piston ring end gap
• Excessive cylinder bore wear or taper
• Cylinder damage
• Piston damage
1. Start the engine and deter.mine i.f the noise is timed to the engine camshaft
speed or the crankshaft speed.
2. Using a timing light, two knocks per flash is the crankshaft speed and
one knock per flash is the engine camshaft speed.
3. If the noise is timed to the engine camshaft speed, inspect the following:
• Missing or loose valve train components
• Worn or loose valve. r9cker arms
• Worn or bent valve pushrods
• .·Faulty valve springs
· • Bent or burnt valves
• Worn engine camshaft lobes
• Worn or damaged camshaft timing chain and/or sprockets
Important: A slight COLD kno'ck or piston slapping noise could be considered
normal if not present after the engine has reached normal operating temperatures .
. 4. If the knock is timed to the crankshaft speed, inspect the following:
• Worn crankshaft or connecting rod bearings
• Piston or cylinder damage
• Worn piston or piston pin
• Faulty connecting rod
• · Excessive carbon build-up on the top of the piston
1. Inspect for a worn or improperly installed camshaft timing chain and/or
sprockets.
2. Remove the valve rocker arm cover on the side of the engine with the cylinder
that is misfiring.
3. Inspect for the following:
• Loose valve rocker arm studs
• Bent valve push rods
• Faulty valve springs
• Faulty valve lifters (bleeding down)
• Worn or improperly seated valves
• Worn engine camshaft lobes
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