Oil Filter Bypass Valve; Main Bearing Replacement - GMC G Service Manual

Figure 30 — Measuring Connecting Rod Side
Clearance

OIL FILTER BYPASS VALVE

M Remove or Disconnect (Figure 31)
1. Oil filter.
| f f | Inspect
• Bypass valve spring and valve disc for damage,
cracks, and proper operation. If replacement of
the oil filter bypass valve (93) is needed, pro­
ceed as follows:
2. Bolts (94).
3. Oil filter bypass valve.
k iH Clean
• Valve chamber in the block.
R Install or Connect (Figure 31)
1. Oil filter bypass valve (93).
2. Bolts (94).
I f f l Tighten
• Bolts (94) to 26 N*m (20 ft. lbs.).
SMALL BLOCK 6A4-23
3. Oil filter.
4. Proper quantity and grade of engine oil. Refer to
MAINTENANCE AND LUBRICATION (SEC. OB).

MAIN BEARING REPLACEMENT

M Remove or Disconnect (Figure 32)
Tool Required:
J 8080 Main Bearing Remover/Installer
1. Spark plugs.
2. Oil pan. Refer to "Oil Pan Replacement" in this
section.
3. Oil pump. Refer to "Oil Pump Replacement" in this
section.
4. Main bearing caps.
• Check the main bearing caps for index mark­
ings. Mark the caps if necessary. The caps
must be returned to their original locations dur­
ing assembly.
5. The lower main bearing inserts from the main bearing
caps.
6. The upper main bearing inserts.
• Insert J 8080 into the crankshaft oil hole
(figure 32).
• Rotate the crankshaft to "turn" the bearing insert
out of the block.
Cleaning, Inspection, and Repair
Clean, inspect, and repair or replace the components as
required. Refer to the 1988 Light Duty Trucks Unit Repair
Manual. The unit repair manual contains information on:
• Crankshaft.
• Main and connecting rod bearings.
• Main bearing cap replacement (shimming
procedure).