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Home >> Porsche >> 1986 >> 928 Automatic >> Repair and Diagnosis (Single Page) >> Engine Mechanical >> Mechanical >> 5.0L V8 >> Crankshaft & Rod Bearings >> Crankshaft >> Inspection & Service

Inspection & Service

  1. When inspecting crankshaft, check main bearing insert bores in cylinder block/lower crankcase section for straightness. See CRANKCASE MAIN BEARING BORE MEASUREMENTS . Assemble the lower crankcase section to cylinder block with the main bearing inserts installed.
    NOTE: Crankshaft bearing regrind undersize color codes: Blue paint dot for first undersize, Green dot for second undersize and Yellow dot for third undersize. Replacement main and rod bearings are available in standard and 0.010" (.25 mm), 0.020" 50 mm) and 0.030" (.75 mm) oversize and undersize.
  2. Check crankshaft runout by installing dial indicator and measuring runout on bearing journals No. 2, 3 and 4 with journals No. 1 and 5 on "V" blocks. Standard runout is .0016-.0024" (.040-.060 mm). Maximum runout is 0.0032" (.080 mm). Replace crankshaft if runout is beyond specifications.
  3. Check main bearing inserts for excessive wear or damage and replace as necessary. Inspect crankshaft main and rod bearing journals and oil seal surfaces for nicks, scratches and excessive wear or damage. Replace crankshaft or regrind bearing journals as necessary.
  4. If oil seal surfaces are deeply scored, grind seal surfaces to 2.35" (59.8 mm) for camshaft drive belt end and 3.54" (89.8 mm) for flywheel end. Polish oil seal journals to .8-2 microns.
  5. After grinding, chamfer oil holes to a .02" (.5 mm) radius. Break all sharp edges to a radius of .008-.020" (.20-.50 mm). Crankshaft main and rod bearing journals may be reground 3 times.
  6. If pilot bearing needs replacement, remove bearing with inside jaw puller and install new bearing against stop with bearing driver.
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