General method description: Fault-tracing
The source of a leak can be located by analyzing sound at the following points.
| Exhaust pipe | Faulty exhaust valve |
| Intake manifold / throttle body (TB) | Faulty intake valve |
| Dip stick hole / Crankcase ventilation | Faulty piston / piston ring |
| Adjacent cylinder | Faulty cylinder head gasket |
| Radiator | Faulty cylinder head gasket / cracked cylinder wall. Also check for bubbles in the expansion tank. |
A mechanic's stethoscope or a rubber hose can be used as a listening device.
NOTE:
There is leakage at the piston rings even on a perfect engine.
This is the only place where a small leak is permissible.