Skylark L4-144 2.4L DOHC VIN T SFI (1997)
Crankshaft Main Bearing: Testing and Inspection
Selection
TOOL REQUIRED
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J 36660 Torque Angle Meter
NOTE: The engine bearings are of the precision insert type. The bearings are available for service use in standard and various undersizes.
CAUTION: Do not scrape, shim, or file bearing inserts. If the bearing surface of the insert is touched with bare fingers, the skin oil and acids will etch
the bearing surface.
1. Inspect the bearing surfaces for the following conditions:
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Wear.
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Gouges.
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Embedded foreign material. If you find foreign material, determine its nature and source. Inspect the oil pan sludge and residue.
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Uneven side-to-side wear. If you find uneven wear, check for a bent crankshaft or tapered bearing journals.
2. Inspect the outer surfaces for the following conditions:
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Wear. Surface wear indicates either movement of the insert or high spots in the surrounding material (spot wear).
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Overheating or discoloration
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Looseness or rotation indicated by flattened tangs and wear grooves
3. Inspect the thrust surfaces of the main thrust bearing for the following conditions:
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Wear
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Grooving (Grooves are caused by irregularities of the crankshaft thrust surface.)
CAUTION: If bearing failure is due to other than normal wear, investigate bearing failure carefully. Inspect the crankshaft or connecting rod and
the bearing bores carefully.
4. Inspect the connecting rods or main bearing bores using the following procedure:
a. Tighten the bearing cap to specifications.
b. Measure the bore for taper and out of round.
c. No taper or out of round should exist.
5. Measure the bearing clearance accurately in order to determine the correct replacement insert size. There are two methods to measure bearing
clearance. Method A gives more reliable results and is preferred.
NOTE: 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. Do not mix inserts of different nominal size in the same bearing bore.
6. Choose a method of bearing clearance measurement.
