Engine Block Cleaning and Inspection

Tools Required

• J 7872  Magnetic Base Dial Indicator. See Special Tools .
• J 8087  Cylinder Bore Gage. See Special Tools .

Fig 1: Cleaning Gasket Mating Surfaces
Courtesy of GENERAL MOTORS CORP.
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 .
Fig 2: Checking Deck Surface For Flatness
Courtesy of GENERAL MOTORS CORP.
IMPORTANT: Do not attempt to machine the lower crankcase to engine block surfaces.
8. Use a straight edge and a feeler gage to check the deck surface for flatness. Refer to Engine Mechanical Specifications . 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.
Fig 3: Cleaning Sealing Material From Gasket Mating Surfaces - Engine Block Side
Courtesy of GENERAL MOTORS CORP.
10. Clean the sealing material from the gasket mating surfaces on the lower crankcase engine block side.
Fig 4: Cleaning Sealing Material From Gasket Mating Surfaces - Oil Pan Side
Courtesy of GENERAL MOTORS CORP.
11. Clean the sealing material from the gasket mating surfaces on the lower crankcase oil pan side.
Fig 5: Measuring Engine Block Flange Runout
Courtesy of GENERAL MOTORS CORP.
12. Inspect the mating surfaces of the transmission face.
NOTE: 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. Measure the crankshaft flange runout using the J 7872  . See Special Tools .
    2. Hold the gage 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).
Fig 6: Inspecting Crankshaft Main Bearing Bores
Courtesy of GENERAL MOTORS CORP.
14. Inspect the crankshaft main bearing bores. Use the J 8087  to measure the bearing bore concentricity and alignment. See Special Tools .
15. Replace the engine block and bed plate if the crankshaft bearing bores are out of specification.
Fig 7: Inspecting Cylinder Bores Using J 8087
Courtesy of GENERAL MOTORS CORP.
16. Inspect the cylinder bores using the J 8087  . See Special Tools . Inspect for the following items:
    • Wear
    • Taper
    • Runout
    • Ridging
17. Refer to Engine Mechanical Specifications .
18. If the cylinder bores are out of specification, replace the block.