Hummer H3. Manual — part 487

The valve rocker arm

The valve push rod

The valve lifter

The valve lifter guide

The piston

Inspect the top of the pistons for valve
contact. If the top of the piston shows valve
contact, replace the piston and pin assembly.

Improper lubrication to the valve rocker arms Inspect the following components and repair

or replace, as required:

The valve rocker arm

The valve push rod

The valve lifter

The oil filter bypass valve

The oil pump and pump screen

The engine block oil galleries

Broken valve spring

Replace the valve spring and spring shim.

Worn or dirty valve lifters

Replace the valve lifters, as required.

Stretched or broken timing chain and/or
damaged sprocket teeth

Replace the timing chain and sprockets.

Worn engine camshaft lobes

1. Inspect the engine camshaft lobes.

2. Replace the camshaft and valve lifters,

as required.

Worn valve guides or valve stems

Inspect the following components and repair,
as required:

The valves

The valve guides

Stuck valves
Carbon on the valve stem or valve seat may
cause the valve to stay open.

Inspect the following components and repair,
as required:

The valves

The valve guides

2008 Hummer H3

2008 ENGINE Engine Mechanical - 5.3L - H3

LOWER ENGINE NOISE, REGARDLESS OF ENGINE SPEED

Cut or damaged oil pump screen O-ring seal
which may cause aeration of the engine oil

Repair, as required. Refer to Oil Pressure
Diagnosis and Testing.

Cause

Correction

Low oil pressure

1. Perform an oil pressure test. Refer to

Oil Pressure Diagnosis and Testing.

2. Repair or replace damaged components,

as required.

Worn accessory drive components
Abnormalities such as severe cracking, bumps
or missing areas in the accessory drive belt
and/or misalignment of system components.

1. Inspect the accessory drive system.

2. Repair or replace, as required.

Loose or damaged crankshaft balancer

1. Inspect the crankshaft balancer.

2. Repair or replace, as required.

Detonation or spark knock

Verify the correct operation of the ignition
controls system. Refer to Symptoms -
Engine Controls .

Loose torque converter bolts

1. Inspect the torque converter bolts and

flex plate.

2. Repair or replace, as required.

Loose or damaged flywheel or flex plate

Repair or replace the flywheel or flex plate.

Oil pump screen loose, damaged, or
restricted

1. Inspect the oil pump screen.

2. Repair or replace, as required.

Excessive piston-to-cylinder bore clearance

1. Inspect the piston and cylinder bore.

2. Repair, as required.

Excessive piston pin-to-bore clearance

1. Inspect the piston, pin, and connecting

rod.

2. Replace the piston and pin as an

assembly, as required.

Excessive connecting rod bearing clearance

Inspect the following components and repair,
as required:

The connecting rod bearings

2008 Hummer H3

2008 ENGINE Engine Mechanical - 5.3L - H3

ENGINE NOISE UNDER LOAD

The connecting rods

The crankshaft

The crankshaft journals

Excessive crankshaft bearing clearance

Inspect the following components and repair,
as required:

The crankshaft bearings

The crankshaft journals

Incorrect piston, piston pin, and connecting
rod installation
Pistons must be installed with the mark or
dimple on the top of the piston facing the
front of the engine. Piston pins must be
centered in the connecting rod pin bore.

1. Verify the pistons, piston pins and

connecting rods are installed correctly.
Refer to Piston, Connecting Rod, and
Bearing Installation.

2. Repair, as required.

Cause

Correction

Low oil pressure

1. Perform an oil pressure test. Refer to

Oil Pressure Diagnosis and Testing.

2. Repair or replace, as required.

Detonation or spark knock

Verify the correct operation of the ignition
controls. Refer to Symptoms - Engine
Controls .

Loose torque converter bolts

1. Inspect the torque converter bolts and

flex plate.

2. Repair, as required.

Cracked flex plate - automatic transmission

1. Inspect the flex plate bolts and flex

plate.

2. Repair, as required.

Excessive connecting rod bearing clearance

Inspect the following components and repair,
as required:

The connecting rod bearings

The connecting rods

The crankshaft

2008 Hummer H3

2008 ENGINE Engine Mechanical - 5.3L - H3

ENGINE WILL NOT CRANK - CRANKSHAFT WILL NOT ROTATE

Excessive crankshaft bearing clearance

Inspect the following components and repair,
as required:

The crankshaft bearings

The crankshaft journals

The cylinder block crankshaft bearing
bore

Cause

Correction

Seized accessory drive system component

1. Remove the accessory drive belts.

2. Confirm that the engine will rotate.

Rotate the crankshaft by hand at the
crankshaft balancer or flex plate
location.

3. Repair or replace the components, as

required.

Seized automatic transmission torque
converter

1. Remove the torque converter-to-flex

plate bolts.

2. Confirm that the engine will rotate.

Rotate the crankshaft by hand at the
crankshaft balancer or flex plate
location.

3. Repair or replace the components, as

required.

Broken timing chain

1. Inspect the timing chain and sprockets.

2. Repair or replace the components, as

required.

Seized timing chain or timing sprockets

1. Inspect the timing chain and sprockets

for foreign material or a seized chain.

2. Repair or replace the components, as

required.

Seized or broken camshaft

1. Inspect the camshaft and the camshaft

bearings.

2. Repair or replace the components, as

2008 Hummer H3

2008 ENGINE Engine Mechanical - 5.3L - H3