Crankshaft And Bearing Cleaning And Inspection

Special Tools

• EN-8087  Cylinder Bore Checking Gauge
• EN-45059  Angle Meter
• GE-7872  Magnetic Base Dial Indicator Set

For equivalent regional tools, refer to Special Tools .

Crankshaft Cleaning and Inspection

Fig 1: Clean Crankshaft With Solvent
Courtesy of GENERAL MOTORS COMPANY
NOTE:

Use care when handling the crankshaft. Avoid damage to the bearing surfaces or the lobes of the crankshaft position reluctor ring. Damage to the teeth of the crankshaft position reluctor ring may affect on-board diagnostic (OBD) II system performance.

1. Clean the crankshaft (1) with solvent.
2. Thoroughly clean all oil passages and inspect for restrictions or burrs.
WARNING:

Refer to Safety Glasses Warning .

3. Dry the crankshaft with compressed air.
NOTE:

Reluctor ring teeth should not have imperfections on the rising or falling edges. Imperfections of the reluctor ring teeth may effect OBD II system performance.

4. Perform a visual inspection of the crankshaft for damage.
Fig 2: Identifying Different Crankshaft Journal Wear Patterns
Courtesy of GENERAL MOTORS COMPANY
5. Inspect the crankshaft journals for wear (1). The journals should be smooth, with no signs of scoring, wear, or damage.
6. Inspect the crankshaft journals for grooves or scoring (2).
7. Inspect the crankshaft journals for scratches or wear (3).
8. Inspect the crankshaft journals for pitting or imbedded bearing material (4).

Crankshaft Measurements

Fig 3: Measure Crankshaft Journals For Out-Of-Round
Courtesy of GENERAL MOTORS COMPANY
1. Measure the crankshaft journals (1) for out-of-round.
2. Measure the crankshaft journals for taper.
Fig 4: Measuring The Crankshaft Runout
Courtesy of GENERAL MOTORS COMPANY
3. Measure the crankshaft runout.

   Using wooden V-blocks, support the crankshaft on the front and rear journals.

4. Use the GE-7872  indicator (1) in order to measure the crankshaft runout at the front and rear intermediate journals.
5. Use the GE-7872  indicator in order to measure the runout of the crankshaft rear flange.
6. Replace the crankshaft if the measurements are not within specifications. Refer to Engine Mechanical Specifications .

Crankshaft Bearings Cleaning and Inspection

Fig 5: Identifying Crankshaft Bearings For Craters Or Pockets
Courtesy of GENERAL MOTORS COMPANY
NOTE:
• Crankshaft bearings MUST be separated, marked, or organized in a way to ensure installation to their original location and position, when suitable for use.
• If crankshaft bearing failure is due to other than normal wear, investigate the cause. Inspect the crankshaft or connecting rod bearing bores.
1. Inspect crankshaft bearings for craters or pockets (1). Flattened sections on the bearing halves also indicate fatigue.
2. Inspect the crankshaft bearings for excessive scoring or discoloration (2).
3. Inspect the crankshaft bearings for dirt or debris imbedded into the bearing material.
4. Inspect the crankshaft bearings for improper seating indicated by bright, polished sections of the bearing (3).

   If the lower half of the bearing is worn or damaged, both upper and lower halves should be replaced.

   Generally, if the lower half is suitable for use, the upper half should also be suitable for use.

Fig 6: Measuring Bearing Bore
Courtesy of GENERAL MOTORS COMPANY
5. Inspect the connecting rod bearing bores or crankshaft main bearing bores using the following procedure:
   1. Tighten the bedplate to specification using the EN-45059  meter.
   2. Measure the bearing bore for taper and out-of-round using the EN-8087  gauge (1).
   3. No taper or out-of-round should exist.

Bearing Selection

1. Measure the bearing clearance to determine the correct replacement bearing insert size. There are 2 methods to measure bearing clearance. Method A gives more reliable results and is preferred.
   • Method A yields measurement from which the bearing clearance can be computed.
   • Method B yields the bearing clearance directly. Method B does not give any indication of bearing run-out.
Fig 7: View of Measuring Crankshaft Bearing Journal Using Method A
Courtesy of GENERAL MOTORS COMPANY
NOTE:

Do not mix inserts of different nominal size in the same bearing bore.

2. To measure bearing clearance using Method A, use the following procedure:
   1. Measure the crankshaft bearing journal diameter with a micrometer (1) in several places, 90 degrees apart. Average the measurements.
   2. Measure the crankshaft bearing journal taper and runout.
   3. Install the lower crankcase and tighten the bearing cap bolts to specification.
   4. Measure bearing inside diameter (ID) in several places 90 degrees apart, average measurements.
   5. Subtract journal measurement from bearing ID measurement to determine clearance.
   6. Determine whether clearance is within specification.
   7. If out of specification, choose different inserts.
   8. Measure the connecting rod inside diameter in the same direction as the length of the rod with an inside micrometer.
   9. Measure the crankshaft main bearing inside diameter with an inside micrometer.
Fig 8: Measuring Bearing Clearance Using Method B
Courtesy of GENERAL MOTORS COMPANY
3. To measure bearing clearance using Method B, use the following procedure:
   1. Clean the used bearing inserts.
   2. Install the used bearing inserts.
   3. Place a piece of gaging plastic across the entire bearing width.
   4. Install the bearing caps.
   CAUTION:

   In order to prevent the possibility of cylinder block or crankshaft bearing cap damage, the crankshaft bearing caps are tapped into the cylinder block cavity using a brass, lead, or a leather mallet before the attaching bolts are installed. Do not use attaching bolts to pull the crankshaft bearing caps into the seats. Failure to use this process may damage a cylinder block or a bearing cap.

   5. Install the bearing cap bolts to specification.
   NOTE:

   Do not rotate the crankshaft.

   6. Remove the bearing cap, leaving the gauging plastic in place. It does not matter whether the gauging plastic adheres to the journal or to the bearing cap.
   7. Measure the gauging plastic at its widest point with the scale (1) printed on the gauging plastic package.
   8. Remove the gauging plastic.