Engine Block Cleaning and Inspection

Tool Required 

• J 8087  Cylinder Bore Gauge
• J 7872  Magnetic Base Dial Indicator Set

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. Clean the threaded holes with a rifle brush. If necessary, drill out the holes and install thread inserts. Refer to THREAD REPAIR  .
   Fig 1: Checking Deck Surface For Flatness

   Courtesy of GENERAL MOTORS CORP.
8. Use a straight edge and a feeler gage 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.
10. Inspect the mating surfaces of the transmission case.
    NOTE: A broken flywheel may result if the transmission case mating surface is not flat.
11. Use the following procedure in order to measure the engine block flange runout at the mounting bolt hole bosses:
    1. 11.1. Temporarily install the crankshaft. Measure the crankshaft flange runout using the J 7872  .
    2. 11.2. Hold the gauge plate flat against the crankshaft flange.
    3. 11.3. Place the dial indicator stem on the transmission mounting bolt hole boss. Set the indicator to 0.
    4. 11.4. 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. 11.5. Recheck the crankshaft flange runout if the readings vary more than 0.203 mm (0.008 in).
       Fig 2: Measuring Engine Block Flange Runout At Mounting Bolt Hole Bosses

       Courtesy of GENERAL MOTORS CORP.
12. Inspect the crankshaft main bearing bores. Use the J 8087  to measure the bearing bore concentricity and alignment at the following locations:
    • The camshaft
    • The crankshaft

      Important:  Recondition the engine block with the crankshaft bearing cap bolts installed and tightened to specification.

13. Ensure that the crankshaft bearing caps are installed correctly. The arrows should point toward the front of the engine.
14. Replace the engine block if the crankshaft bearing bores are out of specification.
    Fig 3: Inspecting Crankshaft Main Bearing Bores

    Courtesy of GENERAL MOTORS CORP.
15. Use the J 8087  to inspect the cylinder bores. Inspect for the following items:
    • Wear
    • Taper
    • Runout
    • Ridging

      Important:  If the bore is worn beyond the limits, refit the bore with oversized pistons. Select the smallest available oversize piston. Refer to PISTON, CONNECTING ROD, AND BEARING INSTALLATION  .

16. Leave sufficient material to allow honing when fitting the piston.
    Fig 4: Inspecting Cylinder Bores

    Courtesy of GENERAL MOTORS CORP.