22 · Diagnostics

Engine hissing

Fault diagnosisEngine hissing

ENGINE HISSING

There is buzzing (low frequency noise) coming from the engine, whose intensity varies with the number of revs

1	AIR CIRCUIT CHECK	All OK	Problems met	Operation
		Results of the tests
	Check: the condition and seal of the air supply circuit	Continue to Step 2	Circuit component damaged	Replace the component (see Assembly 1048A)
2	ENGINE EXHAUST CHECK	All OK	Problems met	Operation
	Check: the condition and the seal of the engine exhaust pipes	Continue to Step 3	Pipe, silencer or connector damaged	Replace the components (see Assembly 1076B)
3	VALVE LEAKAGE TEST	All OK	Problems met	Operation
	Check the condition and the seal of the timing valvesOp. 1016C04	Continue to Step 4	Valves damaged	Replace the component (see Assembly 1016C)
4	CHECKING CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present	End of diagnosis	Fault persists	Search for the fault starting from another symptom'

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