Engine Mechanical - 2.4L: Diagnosis Saturn Aura I

Diagnostic Starting Point - Engine Mechanical

Begin the system diagnosis by reviewing the Disassembled Views , Engine Component Description , Lubrication Description , and Drive Belt System Description . Reviewing the description and operation information will help you determine the correct symptom diagnostic procedure when a malfunction exists. Reviewing the description and operation information will also help you determine if the condition described by the customer is normal operation. Refer to Symptoms - Engine Mechanical in order to identify the correct procedure for diagnosing the system and where the procedure is located.

Strategy Based Diagnostics

1. Perform the «Diagnostic System Check - Vehicle»(ref-301515-S32423278442008101700000) before using the symptom tables, if applicable.
2. Review the system operations in order to familiarize yourself with the system functions. Refer to «Disassembled Views»(ref-301512-S10868456992008101700000) , «Engine Component Description»(ref-301512-S30246407352008101700000) , and «Lubrication Description»(ref-301512-S20045333082008101700000) .

All diagnosis on a vehicle should follow a logical process. Strategy based diagnostics is a uniform approach for repairing all systems. The diagnostic flow may always be used in order to resolve a system condition. The diagnostic flow is the place to start when repairs are necessary.

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the engine.
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.
3. Check for the correct oil level, proper oil viscosity, and correct filter application.
4. Verify the exact operating conditions under which the concern exists. Note factors such as engine RPM, ambient temperature, engine temperature, amount of engine warm-up time, and other specifics.
5. Compare the engine sounds, if applicable, to a known good engine and make sure you are not trying to correct a normal condition.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Base Engine Misfire without Internal Engine Noises»(ref-301512-S31044314762008101700000)
2. «Base Engine Misfire with Abnormal Internal Lower Engine Noises»(ref-301512-S28053433942008101700000)
3. «Base Engine Misfire with Abnormal Valve Train Noise»(ref-301512-S24384459992008101700000)
4. «Base Engine Misfire with Coolant Consumption»(ref-301512-S27585624242008101700000)
5. «Base Engine Misfire with Excessive Oil Consumption»(ref-301512-S13156663602008101700000)
6. «Engine Noise on Start-Up, but Only Lasting a Few Seconds»(ref-301512-S15512085552008101700000)
7. «Upper Engine Noise, Regardless of Engine Speed»(ref-301512-S15264093762008101700000)
8. «Lower Engine Noise, Regardless of Engine Speed»(ref-301512-S05167913622008101700000)
9. «Engine Noise Under Load»(ref-301512-S07851801132008101700000)
10. «Engine Will Not Crank - Crankshaft Will Not Rotate»(ref-301512-S05665576122008101700000)
11. «Engine Compression Test»(ref-301512-S42259640902008101700000)
12. «Oil Consumption Diagnosis»(ref-301512-S00790210632008101700000)
13. «Oil Pressure Diagnosis and Testing»(ref-301512-S34230048572008101700000)
14. «Oil Leak Diagnosis»(ref-301512-S36686192802008101700000)
15. «Drive Belt Chirping, Squeal, and Whine Diagnosis»(ref-301512-S04518358602008101700000)
16. «Drive Belt Rumbling and Vibration Diagnosis»(ref-301512-S21145325732008101700000)
17. «Drive Belt Falls Off and Excessive Wear Diagnosis»(ref-301512-S20082217142008101700000)
18. «Drive Belt Tensioner Diagnosis»(ref-301512-S38993632722008101700000)

Engine Compression Test

Perform the following steps to conduct a compression test.

1. Conduct the following steps to check cylinder compression. Engine should be at room temperature. Disconnect wiring from the ignition module. Remove the spark plugs. Throttle body valve should be wide open. Battery should be at or near full charge.
2. For each cylinder, crank engine through 4 compression strokes.
3. The lowest reading cylinder should not be less than 70 percent of the highest.
4. No cylinder reading should be less than 689 kPa (100 psi).

Oil Consumption Diagnosis

Excessive oil consumption, not due to leaks, is the use of 0.9 L (1 qt) or greater of engine oil within 3 200 kilometers (2,000 miles). The causes of excessive oil consumption include the following conditions

1. External oil leaks Tighten bolts and/or replace gaskets and oil seals as necessary.
2. Incorrect oil level or improper reading of oil level indicator With the vehicle on a level surface, allow adequate drain down time and inspect for the correct oil level.
3. Improper oil viscosity Use recommended SAE viscosity for the prevailing temperatures.
4. Continuous high speed driving and/or severe usage
5. Crankcase ventilation system restrictions or malfunctioning components
6. Valve guides and/or valve stem oil seals worn, or the seal omitted Ream guides and install oversize service valves and/or new valve stem oil seals.
7. Piston rings broken, improperly installed, worn, or not seated properly Allow adequate time for rings to seat. Replace broken or worn rings, as necessary.
8. Piston improperly installed or mis-fitted

Oil Leak Diagnosis

Diagnostic Aids

1. A chirping or squeal noise may be intermittent due to moisture on the drive belts or the pulleys. It may be necessary to spray a small amount of water on the drive belts in order to duplicate the customers concern. If spraying water on the drive belt duplicates the symptom, cleaning the belt pulleys may be the probable solution.
2. If the noise is intermittent, verify the accessory drive components by varying their loads making sure they are operated to their maximum capacity. An overcharged A/C system, power steering system with a pinched hose or wrong fluid, or a generator failing are suggested items to inspect.
3. A chirping, squeal or whine noise may be caused by a loose or improper installation of a body or suspension component. Other items of the vehicle may also cause the noise.
4. The drive belts will not cause a whine noise.

The accessory drive components can have an affect on engine vibration. Vibration from the engine operating may cause a body component or another part of the vehicle to make rumbling noise. Vibration can be caused by, but not limited to the A/C system over charged, the power steering system restricted or the incorrect fluid, or an extra load on the generator. To help identify an intermittent or an improper condition, vary the loads on the accessory drive components.

The drive belt may have a rumbling condition that can not be seen or felt. Sometimes replacing the drive belt may be the only repair for the symptom.

If replacing the drive belt, completing the diagnostic table, and the noise is only heard when the drive belts are installed, there might be an accessory drive component with a failure. Varying the load on the different accessory drive components may aid in identifying which component is causing the rumbling noise.

If the drive belt repeatedly falls off the drive belt pulleys, this is because of pulley misalignment.

An extra load that is quickly applied on released by an accessory drive component may cause the drive belt to fall off the pulleys. Verify the accessory drive components operate properly.

If the drive belt is the incorrect length, the drive belt tensioner may not keep the proper tension on the drive belt.

Excessive wear on a drive belt is usually caused by an incorrect installation or the wrong drive belt for the application.

Minor misalignment of the drive belt pulleys will not cause excessive wear, but will probably cause the drive belt to make a noise or to fall off.

Excessive misalignment of the drive belt pulleys will cause excessive wear but may also make the drive belt fall off.

Drive Belt Tensioner Diagnosis

Engine Mount Inspection

1. Install the engine support fixture. Refer to «Engine Support Fixture»(ref-301512-S41347681902008101700000) .
2. Raise the engine slightly and observe the engine mount. Raising the engine removes the weight from the engine mount and creates a slight tension on the rubber portion.
3. Replace the engine mount if the engine mount exhibits any of the following conditions: The hard rubber is covered with heat check cracks. The rubber is separated from the metal plate of the engine mount. The rubber is split through the center of the engine mount. The engine mount itself is leaking fluid.
4. For engine mount replacement. Refer to «Engine Mount Replacement (First Design)»(ref-301512-S34422971912008101700000) .

Engine Block Cleaning and Inspection

Tools Required

1. J 7872 Magnetic Base Dial Indicator. See «Special Tools»(ref-301512-S32698523102008101700000) .
2. J 8087 Cylinder Bore Gage. See «Special Tools»(ref-301512-S32698523102008101700000) .

1. Clean the sealing material from the gasket mating surfaces.
2. Clean the engine block and lower crankcase in a cleaning tank with solvent appropriate for aluminum.
3. Flush the engine block with clean water or steam.
4. Clean the oil passages.
5. Clean the blind holes.
6. Spray the cylinder bores and the machined surfaces with engine oil.
7. Inspect the threaded holes. Clean the threaded holes with a rifle brush. If necessary, drill out the holes and install thread inserts. Refer to «Thread Repair»(ref-301512-S09395582582008101700000) .
8. Use a straight edge and a feeler gage to check the deck surface for flatness. Refer to «Engine Mechanical Specifications»(ref-301512-S27176441102008101700000) . If the deck surface is out of specification, replace the block. Do not machine the block.
9. Inspect the oil pan rail for nicks. Inspect the front cover attaching area for nicks. Use a flat mill file to remove any nicks.
10. Clean the sealing material from the gasket mating surfaces on the lower crankcase engine block side.
11. Clean the sealing material from the gasket mating surfaces on the lower crankcase oil pan side.
12. Inspect the mating surfaces of the transmission face.
13. Use the following procedure in order to measure the engine block flange runout at the mounting bolt hole bosses: Temporarily install the crankshaft. Measure the crankshaft flange runout using the J 7872 . See «Special Tools»(ref-301512-S32698523102008101700000) . Hold the gage plate flat against the crankshaft flange. Place the dial indicator stem on the transmission mounting bolt hole boss. Set the indicator to 0. Record the readings obtained from all of the bolt hole bosses. The measurements should not vary more than 0.203 mm (0.008 in). Recheck the crankshaft flange runout if the readings vary more than 0.203 mm (0.008 in).
14. Inspect the crankshaft main bearing bores. Use the J 8087 to measure the bearing bore concentricity and alignment. See «Special Tools»(ref-301512-S32698523102008101700000) .
15. Replace the engine block and bed plate if the crankshaft bearing bores are out of specification.
16. Inspect the cylinder bores using the J 8087 . See «Special Tools»(ref-301512-S32698523102008101700000) . Inspect for the following items: Wear Taper Runout Ridging
17. Refer to «Engine Mechanical Specifications»(ref-301512-S27176441102008101700000) .
18. If the cylinder bores are out of specification, replace the block.

Crankshaft Balancer Cleaning and Inspection

1. Clean the crankshaft balancer.
2. Clean the belt grooves of all dirt or debris with a wire brush.
3. Dry the crankshaft balancer with compressed air.
4. Inspect the crankshaft balancer for the following: Worn, grooved, or damaged hub seal surface A crankshaft balancer hub seal surface with excessive scoring, grooves, rust or other damage must be replaced. IMPORTANT: In order for the belt to track properly, the belt grooves should be free of all dirt or debris. Dirty or damaged belt grooves The balancer belt grooves should be free of any nicks, gouges, or other damage that may not allow the belt to track properly. Minor imperfections may be removed with a fine file. Worn, chunking or deteriorated rubber between the hub and pulley

Engine Flywheel Cleaning and Inspection

1. Clean the flywheel in solvent.
2. Dry the flywheel with compressed air.
3. Inspect the manual transmission flywheel for the following: Damaged ring gear teeth Loose or improperly positioned ring gear The ring gear has an interference fit onto the flywheel and should be positioned completely against the flange of the flywheel. A scored, grooved or damaged friction surface
4. Inspect the automatic transmission flywheel for the following: Damaged ring gear teeth Stress cracks around the flywheel-to-crankshaft bolt hole locations Weight saving holes

Camshaft Cleaning and Inspection

1. Inspect the camshaft journals and lobes for wear or scoring.
2. Inspect the camshaft sprocket alignment notch for damage.
3. Inspect the camshaft cover for damage or loose oil control baffles.
4. Clean the camshaft cover.
5. Wash the camshaft in solvent.
6. Oil the camshaft.
7. Inspect the camshaft cover for cracks or other signs of damage.

Camshaft Timing Chain and Sprocket Cleaning and Inspection

1. Inspect the timing chain guides for cracking or wear.
2. Replace the timing chain guides if wear exceeds 1.12 mm (0.045 in) depth on the chain guide surface.
3. Inspect the timing chain tensioner shoe for wear.
4. Replace the timing chain tensioner shoe if wear exceeds 1.12 mm (0.045 in) depth on the chain guide surface.
5. Inspect the timing chain and actuators for wear.
6. Inspect the camshaft actuator faces for signs of movement.
7. Inspect the camshaft actuator teeth and chain for signs of excessive wear, chipping, or seizure of the timing chain links.
8. Inspect the oil nozzle body for collapse or cracks at the bolt boss. Discard and replace the oil nozzle body if it is damaged.
9. Verify oil nozzle oil flow with compressed air.
10. Inspect the timing chain tensioner for the scoring or free movement.
11. Inspect the timing chain tensioner washer and O-ring for damage. If damaged, replace the timing chain tensioner.

Balance Shaft Cleaning and Inspection

1. Clean the balance shafts in solvent.
2. Remove the balance shaft front bearing carriers from the balance shafts.
3. Inspect the bearing surfaces on the balance shafts for scoring or unusual wear.
4. Inspect the balance shaft drive sprockets for wear, damage, or missing teeth. When installing balance shaft drive sprockets tighten to 55 N.m (41 lb ft).
5. Measure the rear bearing journals on the balance shafts, the journals should be 36.723-36.743 mm (1.4458-1.4466 in) in diameter.
6. Measure the front bearing journals on the balance shafts, the front bearing journals should be 20.020-20.000 mm (0.7881-0.7874 in) in diameter.
7. When the balance shafts have been installed in the engine block, check for smooth rotation, sticking, binding, or roughness.

Water Pump and Balance Shaft Chain and Sprocket Cleaning and Inspection

1. Inspect the balance shaft drive chain guides for cracking or wear.
2. Replace the balance shaft drive chain guides if wear exceeds 1.12 mm (0.045 in) depth on the chain guide surface.
3. Inspect the balance shaft drive chain tensioner guide shoe for wear. Replace the balance shaft drive chain tensioner guide shoe if wear exceeds 1.12 mm (0.045 in) depth on the chain guide surface.
4. Inspect the balance shaft drive chain and sprockets for wear.
5. Inspect the crankshaft sprocket faces for signs of movement.
6. Inspect the alignment notch in the balance shaft for cracking or damage.
7. Inspect the water pump, crankshaft, and balance shaft sprocket teeth and chain for signs of excessive wear, chipping, or seizure of the balance shaft drive chain links.
8. Inspect the timing chain tensioner for damage or wear.

Valve Cleaning and Inspection

1. Clean the valves of carbon, oil and varnish. Carbon can be removed with a wire brush. Varnish can be removed by soaking in Parts Immersion Solvent GM P/N 12345368 (Canadian P/N 10953514) or equivalent.
2. Clean the valve guides.
3. Inspect the valve stem for wear (4).
4. Inspect the valve keeper groove for chipping or wear (5). Replace the valve if chipped or worn.
5. Inspect the valve face for burning or cracking (1). If pieces are broken off, inspect the corresponding piston and cylinder head area for damage.
6. Inspect the valve stem for burrs and scratches. Burrs and minor scratches may be removed with an oil stone.
7. Inspect the valve stem for straightness and the valve head for bending or distortion (3) using V blocks. Bent or distorted valves must be replaced.
8. Clean the deposits from the valve face. Inspect the valve face for grooving.
9. Replace the valve if the face is grooved. Valve faces cannot be machined. If worn, or damaged, the valves must be replaced.
10. The valves may be lightly lapped to the valve seats.

Cylinder Head and Gasket Surface Cleaning and Inspection

1. Remove the spark plugs.
2. Inspect the cylinder head gasket and mating surfaces for leaks, corrosion and blow-by. If the gasket has failed, use the following faults to determine the cause: Improper installation Loose or warped cylinder head Missing, off location or not fully seated dowel pins Corrosion in the seal area around the coolant passages Chips or debris in the cylinder head bolt holes Bolt holes in the cylinder block not drilled or tapped deep enough
3. Inspect the cylinder head gasket surface. Cylinder head may be reused if corrosion is found only outside a 4 mm (0.375 in) band around each combustion chamber (1). Replace the cylinder head if the area between the valve seats is cracked (2). Replace the cylinder head if corrosion has been found inside a 4 mm (0.375 in) band around each combustion chamber (3).
4. Clean the cylinder head bolts.
5. Clean the cylinder head. Remove all varnish, soot and carbon to the bare metal.
6. Clean the valve guides.
7. Clean the threaded holes. Use a nylon bristle brush.
8. Clean the remains of the sealer from the plug holes.
9. Inspect the cylinder head bolts for damaged threads or stretching and damaged heads caused by improper use of tools.
10. Replace all suspect bolts.
11. Inspect the cylinder head for cracks. Check between the valve seats and in the exhaust ports.
12. Inspect the cylinder head deck for corrosion, sand inclusions and blow holes.
13. Inspect the cylinder head deck surface for flatness. Refer to «Engine Mechanical Specifications»(ref-301512-S27176441102008101700000) . If the cylinder head is out of specification, replace the cylinder head. Do not machine the cylinder head.
14. Inspect all the threaded holes for damage. Threads may be reconditioned with thread inserts.
15. Inspect the sealing surfaces.
16. Inspect the cylinder head plugs.

Intake Manifold Cleaning and Inspection

1. Clean the intake manifold mating surfaces.
2. Inspect the intake manifold for damage.
3. Inspect the intake manifold for cracks near metallic inserts.
4. Inspect the crankcase ventilation passages in the intake manifold face for blockage.
5. Clean the crankcase ventilation passages with compressed air if necessary. Use a maximum of 172 kPa (25 psi) of air pressure.
6. Replace the intake manifold as necessary.

Exhaust Manifold Cleaning and Inspection

1. Remove the oxygen sensor from the manifold.
2. Clean the exhaust manifold in solvent.
3. Dry the exhaust manifold with compressed air.
4. Inspect the heat shield for damage.
5. Use a straight edge and a feeler gage and measure the exhaust manifold mounting face for warpage. An exhaust manifold face with warpage in excess of 0.25 mm (0.0100 in) may cause an exhaust leak and may effect OBD II system performance. Exhaust manifolds not within specifications must be replaced.

Oil Pan Cleaning and Inspection

1. Clean the oil pan mating surface.
2. Clean the oil pan. Remove all the sludge and the oil deposits.
3. Inspect the threads for the engine oil drain plug.
4. Inspect the oil pan for cracking near the pan rail and the transmission mounting points.
5. Inspect the oil pan for cracking resulting from impact or flying road debris.
6. Inspect the oil pan baffle and pickup screen.
7. Repair or replace the oil pan as necessary.