GMC 1989 Light Duty Truck, Repair Manual, Page: 347 / 998

GENERAL ENGINE MECHANICAL 6A-13
1. Outer camshaft bearings. Drive the bearings into
place using J 6098-01 (figure 20).
Im portant
• Make sure the ca m sh aft bearing hole (or
holes) align with the oil hole (or holes) in the
block. On some engines, the oil holes may be
difficult to see. If so, use a piece of 2 mm
3/32-inch) rod as shown in figure 21 to check
alignment.
2. Inner camshaft bearing. Use tool J 6098-01 (figure
19).
• Assemble the tool with the pilot engaged in
the front bearing and the pilot flange against
the front face of the block.
• Slide the puller screw, with nut and washer,
through the pilot.
• Place the new bearing on the bearing tool.
Hold the bearing tool and bearing against the
bearing bore. Align the bearing oil hole with
the oil hole in the block.
• Thread the puller screw into the bearing tool
enough to hold the tool and bearing in place.
Holding the puller screw with a wrench, turn
the nut with a second wrench to pull the
cam shaft bearing into place.
Remove the puller screw, pilot, and bearing
tool.
Im p o rtan t
• Make sure the ca m sh aft bearing hole (or
holes) align with the oil hole (or holes) in the
block. If it is difficult to see the alignm ent, use
a piece of brass rod as described in step 1.
3. Camshaft rear plug or cap.
— All engines except 2.8 L engines:
• Coat a new camshaft plug with sealer
(Loctite #592 or equivalent).
• In s ta ll th e p lu g flu s h to 0.80 mm
( 1/ 3 2 - i n c h )
deep.
— 2.8 L engines:
• Clean all RTV from the cap and block.
• Apply a 3 mm (Vs-inch) bead of RTV
s e a la n t (GM p a rt no. 1 0 5 2 3 6 6 or
equivalent) to the machined groove on
the block.
• Install the cap while the RTV is still wet.
• Install the retaining bolts and tighten.
HYDRAULIC LIFTERS
Two types of hydraulic lifters are used in engines cov­
ered by this manual - flat type and roller type. Service
procedures are similar for both types.
Hydraulic lifters are serviced only as an assembly. No
internal parts are available. Service is limited to a disas­
sembly, cleaning and test operation. It is understood that
most technicians discard any suspicious valve lifters. This
information is offered for those who may wish to overhaul
and test valve lifters.
]}
Im portant
Whenever the camshaft needs to be replaced, a
new set of hydraulic lifters must also be installed
(except 2.5 L engines).
INSPECTION BEFORE
DISASSEMBLY
Inspect (Figures 22, 23, and 24)
Lifter body (221) for scuffing and scoring. If the lifter
body wall is worn or damaged, the mating hydraulic
lifter bore in the cylinder block should also be
checked.
Check the fit of each valve lifter in its mating bore in
the block. If the clearance is excessive, try a new
lifter.
Push rod seat. If w orn, inspect the pushrod.
Replace the pushrod, if worn.
— Lifter foot (flat type lifters). The lifter foot must be
smooth and slightly convex. If worn, pitted, or
damaged the mating camshaft lobe should also be
checked.
— Roller (roller type lifters) for:
— Freedom of movement. Free-up or replace the
lifter.
— Flat spots. Replace the lifter, if worn.
— Pitting, replace the lifter if pitted.
— Missing or broken needle bearings.
HYDRAULIC LIFTER OVERHAUL
❖
D isassem ble (Figures 21 throu g h 26)
Retainer (figure 25).
• Push the pushrod seat (228) down, using a
pushrod.
• Pry out the retainer with a screwdriver.
Pushrod seat (228).
Metering valve (227).
Plunger (226) and plunger spring (222).
• If the plunger is stuck, turn the lifter body
upside down and tap it on a flat surface.
Check ball retainer (223), check ball spring (224),
and check ball (225). Pry the check ball retainer
from the plunger, using a small screwdriver (figure
26).