Hummer H3. Manual — part 280

Lower Engine Noise, Regardless of Engine Speed

Cause

Correction

Low oil pressure

Perform an oil pressure test. Refer to
Oil Pressure Diagnosis and Testing.

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.

Inspect the accessory drive system.

Repair or replace as required.

Loose or damaged crankshaft balancer

Inspect the crankshaft balancer.

Repair or replace as required.

Detonation or spark knock

Verify the correct operation of the ignition
system. Refer to Detonation/Spark Knock
in engine controls.

Loose torque converter bolts

Inspect the torque converter bolts and
flywheel.

Repair or replace as required.

Loose or damaged flywheel

Repair or replace the flywheel.

Oil pump screen loose, damaged or restricted

Inspect the oil pump screen.

Repair or replace as required.

Oil transfer tube loose, damaged or restricted

Inspect the transfer tube.

Repair or replace as required.

Excessive piston-to-cylinder bore clearance

Inspect the piston and cylinder bore.

Repair as required.

Excessive piston pin-to-bore clearance

Inspect the piston, piston pin and the
connecting rod.

Repair or replace as required.

Excessive connecting rod bearing clearance

Inspect the following components and repair
as required:

The connecting rod bearings

The connecting rods

The crankshaft

2007 Hummer H3

2007 ENGINE Engine Mechanical - 3.7L - H3

ENGINE NOISE UNDER LOAD

Engine Noise Under Load

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 arrow or
paint on the top of the piston facing the front
of the engine. From the bottom, the squared
pin boss must be toward the front of the
engine.

Verify the pistons, piston pins and
connecting rods are installed correctly.

Repair as required.

Cause

Correction

Low oil pressure

Perform an oil pressure test. Refer to
Oil Pressure Diagnosis and Testing.

Repair or replace as required.

Detonation or spark knock

Verify the correct operation of the ignition
system. Refer to Detonation/Spark Knock
in engine controls.

Loose torque converter bolts

Inspect the torque converter bolts and
flywheel.

Repair as required.

Cracked flywheel (automatic transmission)

Inspect the flywheel bolts and flywheel.

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

Excessive crankshaft bearing clearance

Inspect the following components and repair

2007 Hummer H3

2007 ENGINE Engine Mechanical - 3.7L - H3

ENGINE WILL NOT CRANK - CRANKSHAFT WILL NOT ROTATE

Engine Will Not Crank - Crankshaft Will Not Rotate

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 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.

2007 Hummer H3

2007 ENGINE Engine Mechanical - 3.7L - H3

COOLANT IN COMBUSTION CHAMBER

Bent valve in the cylinder head

Inspect the valves and the cylinder head.

Repair or replace the components as
required.

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.

2007 Hummer H3

2007 ENGINE Engine Mechanical - 3.7L - H3