Hummer H1 (2002+). Manual - part 24

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 Engine  2-57

®

05745159

Front Cover Removal

1.

Remove baffle from front cover (Figure 2-87).

2.

Remove bolts attaching front cover to oil pan.

3.

Remove bolts attaching front cover to engine block.

4.

Remove front cover. Use mallet to loosen cover. Do not
pry cover loose.

5.

Remove oil seal from cover.

Figure 2-87:   Front Cover and Baffle Removal

Timing Chain, Drive Sprockets, Drive Gear 
Removal

1.

Measure timing chain deflection. Deflection must not exceed 
0.810 in. (21 mm). Use dial indicator J–8001 (Figure 2-89).

2.

Measure camshaft end play. End play should not exceed
0.012 in. (0.3 mm). If end play exceeds 0.012 in. (0.3
mm), camshaft sprocket, thrust plate, or spacer is worn
and will have to be replaced.

3.

Remove injection pump drive gear bolt and remove drive
gear from camshaft.

4.

Remove crankshaft sprocket, camshaft sprocket, and
timing chain as assembly  (Figure 2-88).

Figure 2-88:   Timing Chain, Drive Sprocket,

Drive Gear Removal

5.

Remove drive keys from camshaft and crankshaft. 

Figure 2-89:   Measuring Timing Chain Deflection

Oil Filter, Adapter, and Oil Pressure Sending 
Unit Removal

1.

Remove oil filter from adapter (Figure 2-89). Discard oil 
filter.

2.

Remove adapter bolt, washer, seals and adapter.

3.

Unplug electrical connector and remove oil pressure
sending unit from engine valley (Figure 2-91).

COVER OIL SEAL

BAFFLE

FRONT

CYLINDER BLOCK

OIL PAN

 COVER

DRIVE KEYS

CRANKSHAFT

TIMING CHAIN

CRANKSHAFT

CAMSHAFT SPROCKET

DRIVE GEAR

CAMSHAFT

INJECTION PUMP

 SPROCKET

CHAIN

DIAL

INDICATOR

J8001

2-58

Engine

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Figure 2-90:   Oil Filter and Adapter Removal

Figure 2-91:   Oil Pressure Sending Unit Location

Oil Pan Removal

1.

Drain oil from pan if not previously done.

2.

Remove pan bolts.

3.

Tap pan with rubber mallet to loosen. Then remove pan.

4.

Remove pan rear seal (Figure 2-92). Discard seal.

Figure 2-92:   Oil Pan Removal

Oil Pump and Drive Removal

1.

Remove nut from pump mounting stud (Figure 2-93).

2.

Loosen bracket clamp screw and rotate bracket off
mounting stud.

3.

Remove pump mounting stud.

4.

Lift and remove pump and pump shaft.

5.

Remove oil pump drive clamp.

6.

Lift and remove oil pump drive from block  (Figure 2-94).

7.

Remove and discard pump drive gasket.

Figure 2-93:   Oil Pump Removal/Installation

SEAL

ADAPTER

SEALS

WASHER

OIL FILTER

BOLT

OIL PRESSURE

 SENDING UNIT

STUDS

DRAINPLUG

GASKET

OIL PAN

SEAL

OIL PUMP

MOUNTING

BOLT

PUMP DRIVE

SHAFT

SHAFT

 RETAINER

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 Engine  2-59

®

05745159

Figure 2-94:   Oil Pump Drive Removal

Camshaft Removal

1.

Remove thrust plate and spacer  (Figure 2-95).

CAUTION: Support camshaft during removal to avoid damag-
ing bearings.

2.

Remove camshaft from cylinder block.

Figure 2-95:   Camshaft Removal

Piston and Connecting Rod Removal

1.

Remove ridge at top of each cylinder bore with ridge 
reamer J–24270. Remove shavings - chips afterward.

2.

Paint mark pistons for assembly reference.

3.

Mark connecting rod caps with punch, if caps do not have
factory marks.

4.

Remove each piston - connecting rod assembly as follows
(Figure 2-96):

a.

Remove number one piston connecting rod cap nuts.

b.

Remove rod cap and bearing half. Retain bearing for 
select fit reference.

c.

Slide lengths of appropriate size rubber hose over 

Figure 2-96:   Piston and Connecting Rod Removal

CLAMP

OIL PUMP DRIVE

GASKET

CYLINDER BLOCK

THRUST PLATE

CAMSHAFT

SPACER

NUTS

ROD CAP

BEARING

BEARING

PISTON

ROD BOLT

CONNECTING ROD

ROD CAP

CRANKSHAFT

2-60

Engine

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®

Flywheel Removal

1.

Remove six capscrews and flywheel from crankshaft 
(Figure 2-97).

2.

Remove flywheel attaching bolts with impact wrench and
suitable size socket.

3.

Work flywheel off crankshaft flange with rocking motion.

Figure 2-97:   Flywheel Removal

Crankshaft and Main Bearings Removal

1.

Inspect main bearing caps. Note if caps have factory I.D. 
markings on them. However, if caps do not have factory 
marks, it will be necessary to mark each cap with a center 
punch, or scriber. Main caps must be reinstalled in same 
location and direction, to maintain bore alignment for 
crankshaft journals  (Figure 2-98).

2.

Remove rear main oil seal.

3.

Remove main bearing cap bolts. Discard bolts.

4.

Tap main bearing caps with rawhide mallet to loosen.
Then lift and remove caps. Keep them in order of removal
(Figure 2-99).

5.

Lift crankshaft out of bearing saddles in block. Place
crankshaft on bench for cleaning and inspection.

6.

Remove main bearing upper halves from block. Keep
bearing halves for inspection and select fit reference.

Figure 2-98:   Main Bearing Cap I.D. Marks

Figure 2-99:   Crankshaft and Bearing Removal

CYLINDER BLOCK SERVICE

Cleaning

The block can be cleaned with standard parts cleaning equip-
ment. However, if the crankcase and bores are heavily coated
with varnish, gum, carbon, sludge, or rust deposits in the cool-
ant passages, hot tanking will be necessary.

Clean out all oil galleys and water passages with wire brushes
designed for this purpose.

WARNING:  The cam bearings  (Figure 2-100) must be
replaced if the block is “hot tanked”. The caustic solu-
tion used for this type of cleaning, will etch and weaken
bearing surfaces. The expansion plugs and oil filter
pressure regulating valve must also be removed before
hot tank cleaning.

Coat the block with a light solvent after cleaning to prevent
rust formation. Useful solvents are available from LPS Corp.,
Solder Seal, WD-40 and similar firms.

CRANKSHAFT

FLYWHEEL

    FLANGE

MAIN BEARING CAPS

CAP BOLTS

(4 EACH)

CAP LOCATION

AND I.D. MARKS

(REAR MAIN)

CAP

BEARING

BEARING

CRANKSHAFT

REAR

MAIN

OIL

SEAL

NO. 5

NO. 4

CAP

NO. 3

(THRUST)

CAP

NO. 2

CAP

NO.1

(FRONT)

CAP

INSERTS

INSERTS