Tools Required

J 8087  Cylinder Bore Gage

1. Clean all the remaining sealing or gasket material from the sealing surfaces.
2. Clean the engine block with cleaning solvent.
3. Flush the engine block with clean water or steam.
4. Clean the cylinder bores.
5. Clean the oil galleries and the oil passages.
6. Clean the scale and the deposits from the coolant passages.
   NOTE: Clean all dirt, debris, and coolant from the engine block cylinder head bolt holes. Failure to remove all foreign material may result in damaged threads, improperly tightened fasteners or damage to components.
7. Clean the engine block cylinder head bolt holes.
8. After cleaning the engine block, spray or wipe the cylinder bores and the machined surfaces with clean engine oil.
9. Inspect the following areas:
   • Coolant jackets (1) for cracks
   • Cylinder bores (2) for scratches or gouging
   • Valve lifter bores (3) for excessive scoring or wear
     Fig 1: Engine Block Components

     Courtesy of GENERAL MOTORS CORP.
   • Threaded holes (4) for damage
   • Crankshaft bearing webs (5) for cracks
   • Crankshaft bearing caps (6) and the crankshaft bearing bores (7) for damage
     • The crankshaft bearing bores should be round and uniform when measuring the inside diameter (ID).
     • The surface where the crankshaft bearings contact the crankshaft bearing bore should be smooth.
     • If a crankshaft bearing cap is damaged and requires replacement, replace the crankshaft bearing cap first, then rebore the engine block crankshaft bearing bores and check for the proper alignment. Finally, check the crankshaft for the proper clearances.
   • Engine block core hole plug bores (8) for damage
   • Engine block (9) for cracks or damage
   • Engine mount bosses (10) for damage
10. Measure the cylinder bores for taper and out-of-round.
    1. 10.1. Depress the plunger on the J 8087  to 7 mm (0.275 in) or until the J 8087  enters the cylinder bore.
    2. 10.2. Center the J 8087  in the cylinder bore and turn the indicator dial to 0.
    3. 10.3. Move the J 8087  up and down the cylinder bore to determine the cylinder bore taper. Refer to Engine Mechanical Specifications .
    4. 10.4. Turn the J 8087  to different points around the cylinder bore to determine the cylinder bore out-of-round condition. Refer to Engine Mechanical Specifications .
    Fig 2: Measuring Cylinder Bores For Taper & Out-Of-Round Using J 8087

    Courtesy of GENERAL MOTORS CORP.