Procedure 2 - Engine Repair
IMPORTANT:Before preceding with engine repair, consideration should be given to engine assembly replacement. Saturn may have warranted remanufactured engine assemblies available for this vehicle. Oil consumption may also be caused by one or more of the following conditions:
^ Engine oil level not being properly checked
^ External oil leakage
^ Incorrect positive crankcase ventilation (PCV) valve installed
^ Oil control ring(s) worn
^ Compression ring(s) worn
^ Cylinder bores worn and/or poor surface finish Cylinder bores tapered, scored or out-of-round Oil leakage between the valve guide and cylinder head
^ Piston ring(s) not installed correctly
^ Oil leakage past the valve stem seal(s)
^ Poor surface finish on the valve stem(s), (scuffs, scores and burrs)
The compression check will identify damaged pistons and/or rings, valves, head gasket and carbon build-up on pistons or in the combustion chamber, etc.
A cylinder leakage test will identify location of compression loss (damaged intake or exhaust valve, piston or rings, cylinder head or gasket, etc.).
1. Remove and inspect spark plugs. Oil fouling or oil residue on a spark plug electrode may indicate the cylinder that may have damaged valve stem guides, cylinder bores and/or piston rings.
2. Check cylinder compression. Refer to "Compression Check" procedures in appropriate year Engine Mechanical or Engine/Fuel/Air Intake/Exhaust Service Manual, for vehicle being worked on.
3. Check cylinder leakage. Refer to "Cylinder Leakage Test" procedure in appropriate year Engine Mechanical or Engine/Fuel/Air Intake/Exhaust Service Manual, for vehicle being worked on.
IMPORTANT:
The air pressure shut off valve must be closed when adjusting regulator to 689 kPa (100 psi). Then, open shut off valve and allow air pressure to stabilize before recording air pressure/cylinder leakage to obtain accurate readings.
4. If compression and cylinder leakage are not within specification, refer to the appropriate year Engine Mechanical or Engine/Fuel/Air Intake/Exhaust Service Manual for further diagnosis.
5. If compression and cylinder leakage are within specification, remove, disassemble and inspect cylinder head for oil leakage at the bottom of valve guides and between the valve guide outside diameter and cylinder head casting. If oil or carbon residue is present at the:
^ Bottom of the valve guide, oil is leaking past the valve stem seal. If oil is leaking past the valve stem seal, inspect the valve stem for scratches, scuffs, scores and burrs. Carbon deposits should be similar in appearance when comparing intake or exhaust valves to each other. A difference in appearance may indicate oil is leaking between the valve guide and cylinder head, or past the valve stem seal. Measure the valve to guide oil clearance using the appropriate year Engine Mechanical or Engine/Fuel/Air Intake/Exhaust Service Manual. Replace intake and/or exhaust valves, guides and all stem seals as required.
IMPORTANT:
Only Saturn recommended essential tools must be used to remove valve spring retainers. Use of other tools can cause valve stem and seal damage resulting in oil consumption.
^ Valve guide outside diameter next to the cylinder head casting, the oil is leaking between the outside diameter of the valve guide and the cylinder head casting. (To help identify an oil leak between the outside diameter of the guide and the cylinder head casting, apply several drops of engine oil dye SA9176NE around the outside diameter of the valve guide and allow to sit for a minimum of three minutes. Use Black Light Kit SA9175NE to identify oil leak location.)
Oil leaking between the outside diameter of the valve guide and the cylinder head casting can be caused by a damaged cylinder head casting valve guide bore. If oil is leaking between the outside diameter of the valve guide and the cylinder head casting, refer to the appropriate year Engine Mechanical or Engine/Fuel/Air Intake/Exhaust Service Manual, and install an oversize valve guide.
6. Remove the connecting rod and piston assemblies from the engine and inspect the rings for correct installation, sticking and wear. The oil control rings must rotate freely on the piston. Aligned piston rings end gaps will not cause oil consumption. (Refer to appropriate year Engine Mechanical or Engine/Fuel/Air Intake/Exhaust Service Manual.)
7. If the pistons are to be reused:
^ Remove and discard the piston rings, and soak the piston in GM Piston and Ring Cleaner (P/N 12378549), or equivalent, to remove the carbon deposits in the ring land and piston tops.
^ After soaking the pistons, carefully remove any remaining carbon deposits from the ring grooves by using a piece of ring from the old piston ring set.
8. Refer to the procedures in the appropriate year Engine Mechanical or Engine/Fuel/Air Intake/Exhaust Service Manual, and check for cylinder bore scoring, wear, taper and out-of-round (use Dial Bore Gauge SA9178NE-A or equivalent). The specific procedures must be followed to determine if the cylinder can be flex honed. If the cylinder bores are not within specification, oversize pistons or a new cylinder block will be required to repair the engine.
9. If all cylinder bore checks are within specification, hone the cylinder bores using the Saturn recommended Flex Hone SA9171E, 83 mm (3.25 inches) bore and 320 grit, silicone carbide hone.
NOTICE:
Make sure crankshaft pulley/damper keyway is at 3 or 9 o'clock position to prevent damage of crankshaft connecting rod journals during honing.
^ Hone the cylinder bores using a 10W-30 or 5W-30 weight motor oil and the Flex Hone (SA9171E).
^ Make sure the flex hone is rotating upon entry and removal from the cylinder bore.
IMPORTANT:
The recommended speed of the flex hone is 150-200 rpm. Do not use air pressure driven or high-speed tools.
^ Use 60 strokes per minute. Honing time should be approximately 20 seconds or 20 strokes per cylinder to develop a 40-50 degree (included angle) honing cross-hatch. One "stroke" consists of a full downward and upward motion of the flex hone in the cylinder bore.
^ Thoroughly scrub all cylinder bores after honing with a scrub brush, a strong solution of hot water and Tide(R) powder laundry detergent or equivalent. Thoroughly rinse with hot clean water (high-pressure, if available).
NOTICE:
If the cylinder bores are not thoroughly cleaned, the residual grit from the honing stones will wear out the piston rings and cylinder bores extremely fast, resulting in oil consumption. Never use solvent to clean cylinder bores; it only redistributes the grit on the cylinder walls; detergent and hot water will carry the grit away.
^ Dry the cylinder bores and wipe them with a clean white towel saturated with engine oil. Dark residual grit on the towel after wiping the cylinder bore indicates the bores are not clean. The cylinder bore cleaning process described previously must be repeated until the towel is free of all dark residual grit.
NOTICE:
Do not use abrasive pads to clean cylinder head and block surfaces that are sealed with the cylinder head gasket. Bristles or particles from abrasive pads can cause cylinder bore scoring and/or piston ring damage. Gasket material on cylinder head and block surfaces that are sealed with the cylinder head gasket should be removed with a plastic or wood scraper.
10. Install pistons with new rings and re-assemble engine. Refer to appropriate year Engine Mechanical or Engine/Fuel/Air Intake/Exhaust Service Manual.