Engine Block Cleaning and Inspection: Notes

Special Tools

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

For equivalent regional tools, refer to Special Tools .

Fig 1: Sealing Material And Engine Block
Courtesy of GENERAL MOTORS COMPANY
1. Clean the sealing material from the engine block (1) and lower crankcase (2) gasket mating surfaces with a suitable tool.
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: Using Straight Edge
Courtesy of GENERAL MOTORS COMPANY
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: Measuring Crankshaft Flange Runout Using Dial Indicator
Courtesy of GENERAL MOTORS COMPANY
10. Inspect the mating surfaces of the transmission face.
CAUTION:

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. Temporarily install the crankshaft and upper bearings. Measure the crankshaft flange runout using the GE-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 4: View Of Cylinder Bore Gauge
Courtesy of GENERAL MOTORS COMPANY
12. Install the bed plate and bolts. Tighten the bed plate bolts to specification.
13. 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 (LTG) .
14. Replace the engine block and bed plate if the crankshaft bearing bores are out of specification.
15. Remove the bed plate.