Injection Timing Adjustment; Marking Tdc On The Front Housing - GMC G Service Manual

6C2-8 DIESEL FUEL INJECTION
R Install or Connect
1. New gasket.
2. Injection pump to the front cover.
• Align the locating pin on the pump hub with the
slot in the injection pump driven gear (13) (fig­
ure 9).
• Align the timing marks (figure 10).
3. Nuts (11).
Tighten
• Nuts to 42 N«m (31 ft. lbs.).
— Check the timing mark alignment before
fully torquing the nuts.
4. Drive gear to injection pump bolts (10) (figure 8).
I ^ l Tighten
• Bolts to 23 N«m (17 ft. lbs.).
5. Fuel return line.
6. Injection lines.
7. Accelerator cable.
8. Detent cable (if equipped).
9. Electrical connections at the injection pump.
10. Oil pan dipstick tube at the left cylinder head.
11. Injection lines to the brackets.
12. Wire looms to the injection lines.
13. Fuel filter and bracket including the line to the injec­
tion pump.
14. Oil fill tube grommet.
15. Oil fill tube.
16. Oil fill tube nuts.
17. Rubber hose to the oil fill tube.
18. Upper fan shroud. Refer to RADIATOR (SEC. 6B2).
19. Windshield washer bottle.
20. Hood latch cable.
21. Hood latch. Refer to SHEET METAL (SEC. 2B).
22. Air inlet hose.
c l e a n e r
23. Intake manifold. Refer to 6.2 LITER DIESEL (SEC.
6A6).
24. Engine cover.
25. Negative battery cable.

INJECTION TIMING ADJUSTMENT

For the engine to be properly timed, the marks on the top
of the engine front cover must be aligned with the marks on
the injection pump flange (figure 10). The engine must be
off when the timing is reset. Align the scribe marks or half
circles.
\ ^ \ Adjust
1. Injection timing.
• Loosen the three pump retaining nuts.
• Align the mark on the injection pump with the
mark on the front cover.
H X l Tighten
• Pump retaining nuts to 42 N*m (31 ft. lbs.).
2. Throttle rod.
MARKING TDC ON THE FRONT
HOUSING
Tool Required:
J 33042 Timing Fixture
1. Set the engine so that number 1 cylinder is at TDC
(firing).
2. Install J 33042 in the injection pump location.
• Do not use the gasket.
3. The slot in the injection pump gear should be in the
vertical 6 o'clock position (figure 11). If not, remove
J 33042 and rotate the engine crankshaft 360
degrees. The timing marks on the gears will be
aligned.
4. Fasten J 33042 to the gear and tighten (figure 12).
5. Install one 10 mm nut to the upper housing stud to
hold the tool flange.
• The nut should be finger-tight.
6. Tighten the large bolt (18 mm head) clockwise (look­
ing at the front of the engine) to 48 N«m (35 ft. lbs.).
7. Tighten the 10 mm nut.
8. Check that the crankshaft has not rotated and that the
tools did not bind.
9. Strike the scriber with a mallet to mark TDC on the
front housing.
10. Remove J 33042.
Figure 11 — Slot In Injector Pump
in Driven Gear
F-00137