Timing Chain And Sprocket Replacement - GMC G Service Manual

6A6-16 6.2L DIESEL
2. Front cover to the engine. Install the attaching bolts.
Tighten
• Front cover to block bolts to 45 N*m (33 ft. lbs.).
• Oil pan to front cover bolts to 10. N»m (84 in.
lbs.).
3. Baffle, if equipped.
R & l Tighten
• Baffle bolts and nut to 45 N*m (33 ft. lbs.).
• Align the scribe marks on the front cover and injection
pump. If a new front cover was installed, refer to
"Marking TDC on the Front Housing" in DIESEL
FUEL INJECTION (SEC. 6C2).
4. Injection pump nuts.
E & l Tighten
• Nuts to 42 N*m (31 ft. lbs.).
5. Injection pump gear and bolts. Align the timing marks
(figure 16).
Tighten
• Injection pump gear bolts to 23 N-m (17 ft. lbs.).
f l l Measure
• Clearance between injection pump gear and
baffle, if equipped (figure 15). It is necessary to
maintain a minimum of 1.0 mm (0.040-inch)
between the gear and baffle, or noise may
result.
6. Fuel return line bolts.
7. Torsional damper. Refer to "Torsional Damper and
Front Crankshaft Seal Replacement," in this section.
8. Water pump. Refer to ENGINE COOLING (SEC.
6B1).
• Fill the cooling system with the proper quantity and
grade of coolant. Refer to MAINTENANCE AND
LUBRICATION (SEC. OB).
TIMING CHAIN AND SPROCKET
REPLACEMENT
H Remove or Disconnect (Figure 17)
1. Front cover. Refer to "Front Cover Replacement" in
this section.
[ t i l Measure
• Timing chain free play as follows:
• Mount a dial indicator to the front of the
block.
• Position the dial indicator so that the
plunger contacts the timing chain
between the two gears.
• Pull the chain outward (parallel to the front
face of the block) the maximum amount
with finger pressure on the inside of the
chain.
83. Camshaft Gear
90. Camshaft Sprocket
91. Crankshaft Sprocket
Figure 17 — Timing Chain and Sprockets
• Set the dial indicator to zero.
• Move the chain inward (parallel to the
front face of the block) the maximum
amount with finger pressure on the out­
side of the chain.
• The total indicator travel can be noted.
With used parts, the deflection must not
exceed 20.3 mm (0.800 inch). If the
d efle ctio n exceeds this lim it, the
sprockets and timing chain must be
inspected for wear and replaced as nec­
essary. With new parts the maximum
deflection must not exceed 12.7 mm
(0.500 inch).
2. Injection pump gear.
3. Camshaft gear.
• Align the timing marks (figure 17).
4. Camshaft sprocket with timing chain.
5. Crankshaft sprocket.
B Install or Connect (Figures 15 and 17)
1. Crankshaft sprocket.
2. Camshaft sprocket with timing chain.
] Important
• Align the timing marks (figure 17).
3. Camshaft gear, bolt, and washer.
Tighten
• Bolt to 100 N-m (75 ft. lbs.).
4. Injection pump gear and bolts.
] Important
• Align the timing marks (figure 16).
F & l Tighten
• Bolts to 23 N*m (17 ft. lbs.).
83 90