GMC 1989 Light Duty Truck Repair Manual page 474

6A4-20 4.8 LITER L6
A. Nut
B. Flat Washer
Figure 36— Removing the Rocker Arm Stud
5. Valves (42 and 43). Place them in a rack so they can
be returned to their original position at assembly.
CLEANING AND INSPECTION OF COMPONENTS
Refer to GENERAL ENGINE MECHANICAL (SEC. 6A)
and perform the following:
Clean
• Components as outlined.
Inspect
I f
• Components as outlined.
M easure
• Valve stem clearance.
• Valve spring tension and free length.
Other information outlined includes:
• Valve and seat grinding.
• Valve guide reaming.
ROCKER ARM STUD REPLACEMENT
Tools Required:
J-5802-01 Stud Remover
J-5715 Reamer (0.003-inch oversize) or
J-6036 Reamer (0.013-inch oversize)
J-6880 Stud Installer
Rocker arm studs that have damaged threads or are
loose in cylinder heads should be replaced. New studs
are available in 0.003-inch and 0.013-inch oversize.
1. Place tool J-5802-01 over the stud to be removed.
Install a nut and flat washer. Remove the stud by
turning the nut (figure 36).
2. R eam th e h o le to th e
replacement oversize stud. Use reamer J-5715 for
0.003-inch o versize stu d s; ream er J-6036 for
0.013-inch oversize stud (figure 37).
3. Coat lower end (press-fit area) of stud with hypoid
axle lubricant. Drive the stud into place with a
hammer and tool J-6880. Stud is installed to proper
depth when the tool bottoms on the cylinder head
(figure 38).
B-05245
p ro p e r s iz e fo r th e
ASSEMBLY
*
A ssem ble (Figures 34, 35, and 39)
Tools Required:
J-8062 Valve Spring Compressor
J-23738-A Vacuum Pump
1. New seals (19) (intake valves only). Install the seals
over the valve guides and seat them against the
head.
2. Valves (42 and 43).
• Lubricate the valve stems with engine oil.