Chevrolet Silverado / GMC Sierra. Manual - part 233
ENGINE NOISE UNDER LOAD
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
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
2008 Hummer H2
2008 ENGINE Engine Mechanical - 6.2L - H2
ENGINE WILL NOT CRANK - CRANKSHAFT WILL NOT ROTATE
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
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
2008 Hummer H2
2008 ENGINE Engine Mechanical - 6.2L - H2
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
required.
Bent valve in the cylinder head
1. Inspect the valves and the cylinder
heads.
2. Repair or replace the components, as
required.
Seized oil pump
1. Inspect the oil pump assembly.
2. Repair or replace, as required.
Hydraulically locked cylinder
Coolant/antifreeze in the cylinder
Oil in the cylinder
Fuel in the cylinder
1. Remove the spark plugs and inspect 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. Refer to Coolant in
Combustion Chamber.
2. Inspect for failed/broken head gaskets.
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 rings
Piston material
Foreign material
1. Inspect the cylinder for damaged
components and/or foreign materials.
2. Repair or replace the components, as
required.
Seized crankshaft or connecting rod bearings
1. Inspect crankshaft and connecting rod
2008 Hummer H2
2008 ENGINE Engine Mechanical - 6.2L - H2
COOLANT IN COMBUSTION CHAMBER
bearings.
2. Repair or replace the components, as
required.
Bent or broken connecting rod
1. Inspect the connecting rods.
2. Replace the piston and pin as an
assembly, as required.
Broken crankshaft
1. Inspect the crankshaft.
2. Repair or replace the components, as
required.
Cause
Correction
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.
1. A slower than normal cranking speed may indicate coolant entering the combustion
chamber. Refer to Engine Will Not Crank - Crankshaft Will Not Rotate.
2. Remove the spark plugs and inspect for spark plugs saturated by coolant or coolant in
the cylinder bore.
3. Inspect by performing a cylinder leak-down test. During this test, excessive air
bubbles within the coolant may indicate a faulty gasket or damaged component.
4. Inspect by performing a cylinder compression test. 2 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 - Left Side or Cylinder Head
Replacement - Right Side.
Warped cylinder head
Machine the cylinder head to the proper
flatness, if applicable and replace the cylinder
head gasket. Refer to Cylinder Head
Cleaning and Inspection.
Cracked cylinder head
Replace the cylinder head and gasket.
2008 Hummer H2
2008 ENGINE Engine Mechanical - 6.2L - H2