3022724 - S13 ENGINE RUMBLING

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

		Results of the tests
0	PRELIMINARY CHECKS	All OK	Problems met	Operation
	Carry out a road test to check the conditions which give rise to the noise	Continue to Step 3	The noise also occurs with the engine switched off (when warm)	Continue to Step 1
			The noise occurs when braking	Continue to Step 2
			The noise occurs when steering	Continue to Step 3
1	MULTI-PURPOSE VALVE CHECK	All OK	Problems met	Operation
	Check the condition of the multi-purpose valve on the fuel supply system	Continue to Step 2	Multi purpose valve faulty	Replace the valve Op. 1080E11
2	BRAKE SERVO VACUUM VALVE CHECK	All OK	Problems met	Operation
	Check the condition of the one-way valve on the brake servo vacuum pipe	Continue to Step 3	Brake servo valve faulty	Replace the valve Op.   3330D26
3	CHECK ON POWER STEERING PUMP	All OK	Problems met	Operation
	With the engine running, operate the steering to full lock in both directions	Continue to Step 4	Pump noisy	Replace the power steering pump Op. 4130B24
4	CHECK ON CORRECT OPERATION	All OK	Problems met	Operation
	Check that the fault is no longer present		Fault persists	Search for the fault starting from another symptom'