Special Tools

• EN-7872:  Magnetic Base Dial Indicator
• EN-8087:  Cylinder Bore Gauge

For equivalent regional tools, refer to Special Tools .

Fig 1: Clean Sealing Material From Gasket Mating Surfaces With A Suitable Tool
Courtesy of GENERAL MOTORS CORP.
1. Clean the sealing material from the gasket mating surfaces (2) with a suitable tool (1).
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 .
Fig 2: Use A Straight Edge And Feeler Gage To Check Deck Surface For Flatness
Courtesy of GENERAL MOTORS CORP.
NOTE: Do not attempt to machine the lower crankcase to engine block surfaces.
8. Use a straight edge (1) and a feeler gauge (2) to check the deck surface for flatness. Carefully machine minor irregularities. Replace the block if more than 0.254 mm (0.010 in) must be removed.
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.
Fig 3: Clean Sealing Material From Gasket Mating Surfaces On Lower Crankcase Engine Block Side With Suitable Tool
Courtesy of GENERAL MOTORS CORP.
10. Clean the sealing material from the gasket mating surfaces on the lower crankcase engine block side with a suitable tool (1).
Fig 4: Clean Sealing Material From Gasket Mating Surfaces On Lower Crankcase Oil Pan Side With Suitable Tool
Courtesy of GENERAL MOTORS CORP.
11. Clean the sealing material from the gasket mating surfaces on the lower crankcase oil pan side with a suitable tool (1).
Fig 5: Inspect The Mating Surfaces Of The Transmission Face
Courtesy of GENERAL MOTORS CORP.
12. Inspect the mating surfaces of the transmission face.
CAUTION: A broken flywheel may result if the transmission case mating surface is not flat.
13. Use the following procedure in order to measure the engine block flange runout at the mounting bolt hole bosses:
    1. Temporarily install the crankshaft and upper bearings. Measure the crankshaft flange runout using the EN-7872:  dial indicator (1)
    2. Hold the gauge plate flat against the crankshaft flange.
    3. Place the dial indicator stem on the transmission mounting bolt hole boss. Set the indicator to 0.
    4. Record the readings obtained from all of the bolt hole bosses. The measurements should not vary more than 0.203 mm (0.008 in).
    5. Recheck the crankshaft flange runout if the readings vary more than 0.203 mm (0.008 in).
    6. Remove the crankshaft and bearings.
Fig 6: View of EN-8087 Gage To Measure Bearing Bore
Courtesy of GENERAL MOTORS CORP.
14. Install the bed plate and bolts. Tighten the bed plate bolts to specification.
15. Inspect the crankshaft main bearing bores. Use the EN-8087:  gauge (1) to measure the bearing bore concentricity and alignment. Refer to Engine Mechanical Specifications (LAP, LE8) .
16. Replace the engine block and bed plate if the crankshaft bearing bores are out of specification.
17. Remove the bed plate.
Fig 7: Inspect Cylinder Bores Using EN-8087 Gage
Courtesy of GENERAL MOTORS CORP.
18. Inspect the cylinder bores using the EN-8087:  gauge (1). Inspect for the following items:
    • Wear
    • Taper
    • Runout
    • Ridging
19. If the cylinder bores are out of specification, install a NEW cylinder bore sleeve. Refer to Cylinder Sleeve Removal (LAP, LE8)  and Cylinder Sleeve Installation (LAP, LE8) .