Engine Block Cleaning and Inspection

Tools Required 

• J 8001  Dial Indicator Set
• J 8087  Cylinder Bore Gage

1. Clean the sealing material from the gasket mating surfaces.
2. Boil the engine block in caustic solution.
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.
8. Clean the holes with a tap. Drill out the holes and install thread inserts, as needed.
   Fig 1: Engine Block

   Courtesy of GENERAL MOTORS CORP.
9. Use a straight edge and a feeler gauge in order to test the deck surface for flatness. Carefully machine minor irregularities. Replace the block if more than 0.25 mm (0.010 in) must be removed.
   Fig 2: Testing Deck Surface For Flatness

   Courtesy of GENERAL MOTORS CORP.
10. Inspect the oil pan rail for nicks.

    Inspect the front cover attaching area for nicks. Use a flat mill file in order to remove any nicks.

11. Inspect the mating surfaces of the transmission case.
    NOTE: A broken flywheel may result if the transmission case mating surface is not flat.
Fig 3: Measuring Crankshaft Flange Runout
Courtesy of GENERAL MOTORS CORP.
12. Use the following procedure in order to measure the engine block flange runout at the 6 mounting bolt hole bosses:
    1. Temporarily install the crankshaft. Measure the crankshaft flange runout.
    2. Hold the J 8001  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 0.25 mm (0.010 in).
    5. Retest the crankshaft flange runout if the readings vary more than 0.25 mm (0.010 in). If the crankshaft flange runout is within the specification, replace the engine block.

    Important  : Perform the following inspections, and reconditioning (if necessary), with the crankshaft main bearing caps installed and tightened to specification.

Fig 4: Measuring Bearing Bore Concentricity & Alignment
Courtesy of GENERAL MOTORS CORP.
13. Inspect the crankshaft main bearing bores. Use the J 8087  in order to measure the bearing bore concentricity and alignment at the following locations:
    • The camshaft
    • The crankshaft
14. Replace the engine block if the bores are out of specification.
Fig 5: Inspecting Cylinder Bores
Courtesy of GENERAL MOTORS CORP.
15. Use the J 8087  in order to inspect the cylinder bores. Inspect the bores for the following conditions:
    • Wear
    • Taper
    • Runout
    • Ridging

    Important  : If the bore is worn beyond the limits, refit the bore with 0.5 mm (0.02 in) oversized pistons.

16. Leave sufficient material in order to allow honing when fitting the piston.