GMC C Series 1993, Руководство по ремонту

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5J-12 AIR COMPRESSOR AND GOVERNOR
2. Crankcase (288). ;
• Dirt from the interior.
— Use compressed air to remove dirt.
3. Oil passages.
• Use a wire to open and clean oil passages in
the crankshaft and end covers.
• Use compressed air to remove dirt.
Inspect
1. Cylinder head body (263). ; ^ |;
• Check for cracks,and damage.
• Apply compressed air. to one coolant port and
check for leakage by applying a soap solution
to the exterior of the body. ; ! ;!
• If leakage is found, replace the head: ;i;
2. End cover assembly (280).
• For cracks and external damage.
•.Crankshaft' main bearing (sleeve) for wear and,
flat spots. v , , V
3. Crankcase (288).
• Surfaces for cracks and damage.
• Measure the crankshaft bearings.'Replace the
main bearing or end cover if the measurement
exceeds
0.0065
inch. ,
• Unloader bore bushing for Wear, rust, or dam/
age.
\ — Run a 1/8-inch pipe threaded rod and pull
the bushing;straight up and out. , . ..
• Replace the inlet valve seats if worn or dam­
aged.
4. Crankshaft (277).
' • Threads, keyway, tapered ends, and machined
and ground surfaces for wear, scoring, or dam­
age.
— Standard crankshaft connecting rod journals
are 1.2490 inch to 1.2500 inch in diameter;
If the crankshaft journals are scored, worn;
or out-of-round and cannot be reground,
replace the crankshaft.
— Use 0.010, 0.020, or 0.030 inch undersize
connecting rod bearing inserts. \ j.
— Maintain a 0.004-inch clearance between
■• the main bearing and the main bearing
crankshaft journals. 1
• Clean and oil passages.
5. Cylinder bore (288).
• Grooved walls must be square and have a
good finish. ; ; • .
• Use an inside micrometer or caliper to check
cylinder bores (figure 21).
• Re-bore or hone oversize cylinder bores scored
O r: out-of-round more than 0.0005 inch or
tapered more than 0.002 inch.
— Replace pistons with ,0.010, 0.020, and
0.030 inch oversize pistons and rings.
•F in is h the cylinder bores to a smooth
cross-hatch surface.
• Maintain a 0.0128 to 0.0177-inch clearance
between the piston and cylinder bore.
-^M easure the piston diameter at the top of
the piston and the top two ring lands.
J 6. Connecting rod bearing. : .
• The BX-2150 connecting rod does not use a
replaceable connecting-rod bearing insert. The
connecting rod must be replaced if the bearing
v is, excessively worn:
•iPpsition the locking slots of the connecting rod
' bnd cap next to each other.;
• Maintain a 0.001 to 0.0025-inch clearance
-betWeen ,-the'. connecting rod journal and the
connecting rod bearing after assembling.
N Q ^ IC E : S e e ^‘N o tic e ” o n p a g e 5 J -1 .
7. Checking clearance using plastic gaging material
(figure 22). ■ '
A.; Clean the crankshaft journals,to remove oil.
Important
•The gaging material is soluble in oil. The
' ■ journals must be dry to give an accurate
. reading.
B. Place gaging/materia) on the lower half of the
bearing.
C. Install the connecting rod bap (283) and tighten
the connecting bolts (285).
A.
Width Before Gaging
B. Width After Gaging
C. Plastigage Scale B6091
Figure 21— Measuring the Cylinder Bore
Figure 22—^Measuring Bearing Clearance;