Hummer H3. Manual — part 82

ENGINE WILL NOT CRANK - CRANKSHAFT WILL NOT ROTATE

Engine Will Not Crank - Crankshaft Will Not Rotate

bore

Cause

Correction

Seized accessory drive system component

1. Remove the accessory drive belt.

2. Confirm that the engine will rotate.

Rotate the crankshaft by hand at the
crankshaft balancer or flywheel
location.

3. Repair or replace the components as

required.

Seized automatic transmission torque
converter

1. Remove the torque converter-to-

flywheel bolts.

2. Confirm that the engine will rotate.

Rotate the crankshaft by hand at the
crankshaft balancer or flywheel
location.

3. Repair or replace the components as

required.

Broken timing chain

Inspect the timing chain and gears.

Repair or replace the components as
required.

Seized timing chain or timing gears

Inspect the timing chain and gears for
foreign material or a seized chain.

Repair or replace the components as
required.

Seized or broken camshaft

Inspect the camshaft.

Repair or replace the components as
required.

Bent valve in the cylinder head

Inspect the valves and the cylinder
head.

Repair or replace the components as
required.

2006 Hummer H3

2006 ENGINE Engine Mechanical - 3.5L (L52) - H3

COOLANT IN COMBUSTION CHAMBER

Coolant in Combustion Chamber

Seized oil pump

Inspect the oil pump assembly.

Repair or replace as required.

Hydraulically locked cylinder

Coolant/antifreeze in the cylinder

Oil in the cylinder

Fuel in the cylinder

1. Remove spark plugs and check for fluid

in the cylinder. When rotating the
engine with the spark plugs removed,
the piston (on compression stroke) will
push fluid from the combustion
chamber.

2. Inspect for failed/broken head gasket.

3. Inspect for a cracked engine block or

cylinder head.

4. Inspect for a sticking fuel injector.

5. Repair or replace the components as

required.

Material in the cylinder

Broken valve

Broken piston ring(s)

Piston material

Foreign material

Inspect the cylinder for damaged
components and/or foreign materials.

Repair or replace the components as
required.

Seized crankshaft or connecting rod bearings

Inspect crankshaft and connecting rod
bearings.

Repair or replace the components as
required.

Bent or broken connecting rod

Inspect the connecting rods.

Repair or replace the components as
required.

Broken crankshaft

Inspect the crankshaft.

Repair or replace the components as
required.

Cause

Correction

2006 Hummer H3

2006 ENGINE Engine Mechanical - 3.5L (L52) - H3

COOLANT IN ENGINE OIL

Coolant in Engine Oil

DEFINITION: Excessive white smoke and/or coolant type odor coming from the exhaust
pipe may indicate coolant in the combustion chamber. Low coolant levels, an inoperative
cooling fan, or a faulty thermostat may lead to an "overtemperature" condition which may
cause engine component damage.

A slower than normal cranking speed may indicate coolant entering the combustion
chamber. Refer to Engine Will Not Crank - Crankshaft Will Not Rotate.

Remove the spark plugs and inspect for spark plugs saturated by coolant or coolant in
the cylinder bore.

Inspect by performing a Cylinder Leakage Test. During this test, excessive air
bubbles within the coolant may indicate a faulty gasket or damaged component.

Inspect by performing a cylinder compression test. Two cylinders "side-by-side" on
the engine block, with low compression, may indicate a failed cylinder head gasket.
Refer to Engine Compression Test.

Faulty cylinder head gasket

Replace the head gasket and components as
required. Refer to Cylinder Head Cleaning
and Inspection and Cylinder Head
Replacement.

Warped cylinder head

Replace the cylinder head and gasket. Refer
to Cylinder Head Replacement.

Cracked cylinder head

Replace the cylinder head and gasket.

Cracked cylinder sleeve or engine block

Replace the components as required.

Cylinder head or engine block porosity

Replace the components as required.

Cause

Correction

DEFINITION: Foamy or discolored oil or an engine oil "overfill" condition may indicate
coolant entering the engine crankcase. Low coolant levels, an inoperative cooling fan, or a
faulty thermostat may lead to an "overtemperature" condition which may cause engine
component damage. Contaminated engine oil and oil filter should be changed.

Inspect the oil for excessive foaming or an overfill condition. Oil diluted by coolant
may not properly lubricate the crankshaft bearings and may lead to component
damage. Refer to Lower Engine Noise, Regardless of Engine Speed.

Inspect by performing a Cylinder Leakage Test. During this test, excessive air
bubbles within the cooling system may indicate a faulty gasket or damaged

2006 Hummer H3

2006 ENGINE Engine Mechanical - 3.5L (L52) - H3

ENGINE COMPRESSION TEST

Tools Required

J 38722 Compression Tester. See Special Tools.

A compression pressure test of the engine cylinders determines the condition of the rings, the
valves, and the head gasket.

1. Remove the air duct from the throttle control module.

2. Remove the ignition control modules.

3. Disable the fuel system.

4. Remove the spark plugs.

component.

Inspect by performing a cylinder compression test. Two cylinders "side-by-side" on
the engine block with low compression may indicate a failed cylinder head gasket.
Refer to Engine Compression Test.

Faulty external engine oil cooler

Replace the components as required.

Faulty cylinder head gasket

Replace the head gasket and components as
required. Refer to Cylinder Head Cleaning
and Inspection and Cylinder Head
Replacement.

Warped cylinder head

Replace the cylinder head gasket. Refer to
Cylinder Head Replacement.

Cracked cylinder head

Replace the cylinder head and gasket.

Cracked cylinder sleeve or engine block

Replace the components as required.

Cylinder head, block, or manifold porosity

Replace the components as required.

Faulty sealing on engine front cover

Reseal or replace front cover.

IMPORTANT: The battery must be at or near full charge. Do not block the

throttle open.

2006 Hummer H3

2006 ENGINE Engine Mechanical - 3.5L (L52) - H3