GM Service Manual Online
For 1990-2009 cars only

Complaint/Condition

Possible Cause(s)

Correction(s)

Engine Will not Turn Over

Battery, cranking system or other

electrical problems.

Refer to Battery Charging in Engine Electrical.

Liquid in combustion chamber.

Remove with suction gun. Then crank with plugs removed.

Seized engine.

Repair.

Engine Cranks Normally, But Does not Start

Fuel or ignition system problem.

Refer to "Diagnostics" in the "Engine/Emission Controls" service manual.

Camshaft(s)/Drive.

Inspect chain sprockets, camshaft(s), crankshaft key.

Restricted exhaust system.

Repair.

Hydraulic lifters pump-up when engine is cold.

Improper viscosity engine oil. (Refer to Owner's Handbook/Service Manual recommendations.)

Low compression due to stuck or burned valves, stuck rings, blown head gasket, etc.

Perform a compression test, as outlined in this section. Repair engine as necessary.

Excessive engine oil pressure pumping up hydraulic lifters and holding valves open.

Check compression and oil pressure. If compression is extremely low, less than 690 kPa (100 psi), and oil pressure exceeds 621 kPa (90 psi), replace oil pump regulator valve or faulty lifter(s).

Engine Starts Normally, But Stalls within Five Minutes. Engine Has Low Compression During Initial Cranking after Stall.

Low compression due to hydraulic lifter(s) being pumped up.

Incorrect viscosity oil. (Refer to Owner's Handbook/Service Manual recommendations.)

Rough Idle or Vibration

Fuel, ignition system or emission system problem.

Refer to Battery Charging in Engine Electrical.

Uneven cylinder compression.

Perform a compression test, as outlined in this section. Repair engine as necessary.

Hydraulic Lifter(s).

Replace lifter(s).

Powertrain mounts alignment or adjustment.

Adjust or repair.

Broken valve spring.

Repair.

White Smoke

Usually caused by water vapor, which is a normal by-product of combustion usually seen on cold days.

None required.

If excessive white smoke with engine warmed up, check for possible faulty head gasket, cracked cylinder head, block, intake manifold/gasket.

Repair or replace

Black Smoke

Usually caused by rich fuel mixture.

Refer to "Diagnostics" in the "Engine/Emission Controls" service manual.

Blue Smoke

Usually caused by oil burning in the combustion chambers.

Refer to "Oil Consumption" diagnosis in this section of the service manual.

Excessive Oil Loss

External oil leaks.

Tighten bolts and/or replace gasket/RTV and seals as necessary. Check front crankshaft damper/pulley bolt.

Improper reading of dipstick.

Check oil with vehicle on a level surface. Allow adequate drain down time.

Improper oil viscosity.

Use recommended viscosity for prevailing temperatures.

Continuous high speed driving and/or severe usage.

Continuous high speed operation and/or severe usage will normally cause decreased oil mileage.

Crankcase ventilation or PCV system malfunctioning.

Service as necessary. Check cam/ rocker cover baffles and hoses.

Valve guides and valve stem seals worn, or seals missing.

Service cylinder head.

Cylinder head casting valve guide bore damaged.

Service cylinder head.

Piston rings not seated.

Allow 3,000 miles (4827 km) on vehicle and monitor.

Improperly installed, broken or worn piston rings.

Check mark location during disassembly and replace broken or worn rings as necessary.

Piston improperly installed/damaged.

Replace piston or repair as necessary.

Valve stem seals worn.

Replace all valve (Intake and Exhaust) stem seals.

Low Oil Pressure

Incorrect or faulty oil pressure switch or sensor.

Replace with proper switch or sensor.

Incorrect or faulty oil pressure gauge.

Replace with proper gauge.

Improper oil viscosity.

Replace with proper oil.

Diluted engine oil.

Change engine oil and filter. Repair cause of dilution (rich mixture, etc.).

Frozen water in oil pan.

Thaw water and change oil.

Oil pump worn or scored.

Replace front cover.

Plugged filter.

Replace filter and oil.

Oil pick-up screen loose or plugged.

Clean or replace oil pan.

Hole in oil pick-up tube.

Replace oil pan.

Excessive bearing clearance.

Replace as necessary.

Cracked, porous or plugged oil galleys.

Repair, or replace block.

Regulator valve not seated/spring broken.

Replace regulator valve located in front cover.

Gallery plugs missing or incorrectly installed.

Install plugs or repair as necessary.

Valve Train Noise

Low oil pressure.

Repair as necessary. Refer to Oil Pressure Diagnosis and Testing .

Cylinder head oil gallery plug missing.

Replace oil gallery plug.

Broken valve spring.

Replace spring.

Sticking valves.

Free valves.

Lifters worn, dirty, or faulty.

Refer to "Hydraulic Lifter Diagnostic Chart" in this section.

Camshaft worn or faulty.

Replace camshaft.

Worn valve guides.

Repair as necessary.

Engine Knocks Cold and Continues For Two to Three Minutes. Knock Increases with Torque.

Loose or broken torsional damper or drive pulleys.

Tighten or replace as necessary.

Excessive piston to bore clearance.

Replace piston.

Bent connecting rod.

Replace connecting rod.

Engine has Heavy Knock; Hot with Torque Applied.

Broken balancer or pulleys hub.

Replace parts as necessary.

Loose torque converter bolts.

Tighten bolts.

Accessory belts or tensioner damaged.

Replace belt and/or tensioner.

Exhaust system grounded/loose grommets.

Re-position or replace as necessary.

Flywheel cracked or loose rivets on clutch plate.

Replace flywheel or clutch plate.

Excessive main bearing clearance.

Repair as necessary.

Excessive rod bearing clearance.

Repair as necessary.

Engine has Light Knock; Hot in Light Load Conditions.

Faulty ignition system components or knock sensor system.

Refer to the "Engine/Emission Controls" service manual.

Improper timing.

Refer to the "Engine/Emission Controls" service manual.

Piston pin and/or connecting rod.

Replace piston, pin and/or connecting rod.

Poor quality fuel.

Use fuel of recommended grade.

Loose torque converter bolts.

Tighten bolts.

Exhaust leak at manifold.

Tighten bolts and/or replace gaskets as necessary.

Excessive rod bearing clearance.

Replace bearings as necessary.

Engine Knocks on Initial Start Up; Knock Lasts Only a Few Seconds.

Improper oil viscosity.

Install proper oil viscosity for expected temperatures.

Engine Knocks at Idle Hot

Hydraulic lifter bleed down.

Refer to "Hydraulic Lifter Diagnostic Chart" in this section of the service manual.

Loose or worn accessory drive belt/tensioner.

Check belt tension and/or belt tensioner, replace as necessary.

A/C compressor or generator bearing.

Replace as necessary.

Fuel pump.

Replace pump.

Valve train.

Refer to "Valve Train Diagnosis" in this section of the service manual.

Improper oil viscosity.

Install proper viscosity oil for expected temperatures.

Excessive piston pin clearance.

Install new piston, pin and/or connecting rod.

Connecting rod alignment.

Check and replace rods as necessary.

Insufficient piston to bore clearance. (Cold engine piston knock usually disappears when cylinder's spark plug is grounded out. Cold engine piston knock which disappears in 1.5 minutes should be considered acceptable.)

Service block and piston as required.

Faulty timing chain tensioner or chain guide(s).

Replace timing chain tensioner and/or chain guides as necessary.

Loose vibration damper/pulley.

Torque any or replace worn parts.

Noisy at Idle, Becoming Louder as Engine Speed is Increased To 1500 rpm.

This noise is not connected with lifter malfunction. It becomes most noticeable in the vehicle at 16-24 km/h (10-15 mph) L (Low) range, or 48-56 km/h (30-35 mph) D (Drive) range and is best described as a harsh sound. At slow idle, it may be entirely gone or appear as a light ticking noise in one or more of the following:

   • 

Badly worn or scuffed valve tip and rocker arm pad.

   • 

Excessive valve stem to guide clearance.

   • 

Off square valve spring.

   • 

Excessive valve face runout.

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Valve spring clicking on cap/ broken spring.

Repair as necessary.