Engine Block Cleaning and Inspection

Special Tools

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

Equivalent regional tools: Special Tools 

1. Courtesy of GENERAL MOTORS COMPANY

   Remove the engine block plugs (2) and seals (1).

2. Courtesy of GENERAL MOTORS COMPANY

   Clean the sealing material from the gasket mating surfaces.

3. Clean the engine block (1) and lower crankcase in a cleaning tank with solvent appropriate for aluminum.
4. Flush the engine block with clean water or steam.
5. Clean the oil passages.
6. Clean the blind holes.
7. Spray the cylinder bores and the machined surfaces with engine oil.
8. Inspect the threaded holes. Clean the threaded holes with a rifle brush. If necessary, drill out the holes and install thread inserts. Thread Repair 
NOTE:

Do not attempt to machine the lower crankcase to engine block surfaces.

9. Use a straight edge and a feeler gauge 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.
10. Inspect the oil pan rail for nicks. Inspect the front cover attaching area for nicks. Use a flat mill file to remove any nicks.
11. Clean the sealing material from the gasket mating surfaces on the lower crankcase engine block side.
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 J 7872  indicator.
    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.

14. Courtesy of GENERAL MOTORS COMPANY

    Install the main bearing caps and bolts. Tighten the main bearing cap bolts to specification.

15. Inspect the crankshaft main bearing bores. Use the J-8087  gauge (1) to measure the bearing bore concentricity and alignment. Refer to Engine Mechanical Specifications .
16. Replace the engine block if the crankshaft bearing bores are out of specification.

17. Courtesy of GENERAL MOTORS COMPANY

    Inspect the cylinder bores using the J-8087  gauge (1). Inspect for the following items:

    • Wear
    • Taper
    • Runout
    • Ridging