Cause
| Correction
|
A low rumble/knocking may indicate a crankshaft or piston
(lower engine) concern.
|
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. |
|
Leaking fuel injection nozzle
(A stuck fuel injection nozzle can cause a knocking noise similar to
a damaged piston, connecting rod or connecting rod bearing.)
|
| • | Use the cylinder balance diagnostic procedure to help locate the
cylinder that is the source of the noise. |
| • | Exchange the fuel injection nozzle for one in an adjacent cylinder
to see if the condition persists. |
| • | If the condition follows the fuel injection nozzle to the adjacent
cylinder, and disappears from the original cylinder, the fuel injection nozzle
is at fault. |
| • | Exchange or replace the fuel injection nozzle. |
| • | If the condition does not change, or you still cannot locate the
cylinder that is the source of the noise, continue the diagnosis for mechanical
damage. |
|
Loose or damaged crankshaft balancer
|
| • | Inspect the crankshaft balancer. |
| • | Repair or replace as required. |
|
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.
|
Damaged oil pan, contacting the oil pump screen
(An oil pan that has been damaged may improperly position the oil pump
screen, preventing proper oil flow to the oil pump.)
|
| • | Inspect the oil pump screen. |
| • | Repair or replace as required. |
|
Oil pump screen loose, damaged or restricted
|
| • | Inspect the oil pump screen. |
| • | Repair or replace as required. |
|
Excessive piston-to-cylinder bore clearance
|
| • | Inspect the piston and cylinder bore. |
|
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 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 piston crown indent on top of the
piston towards the outside of the cylinder. Piston pins must be centered
in the connecting rod pin bore.)
|
| • | Verify the pistons, piston pins and connecting rods are installed
correctly. |
|
