18 · Diagnostics

S01 Engine pinging

Make: Alfa Romeo
Model: 147 Factory Service Manual
Year: 2000–2002
Section: Noise/vibrations › S01 Engine pinging

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Fault diagnosisS01 Engine pinging

S01 Engine pinging

The engine makes a cyclical noise, the intensity of which varies with the load and is noticeable during brisk acceleration and when long gear ratios are used

Step	Test procedure	Result	Action
1	CHECKING WITH DIAGNOSTIC EQUIPMENT Connect the diagnostic equipment to the diagnostic socket and check: that there are no faults in the engine management control unit	OK	Move onto step 2
1		An error is detected in the control unit	Continue following the instructions for the diagnostic equipment End of diagnosis
2	CHECKING AUXILIARY COMPONENTS CHECK Disconnect the service belt and check whether the noise disappears. NOTE: Do not let the engine run for long with the belt disconnected	OK	Move onto step 3
2		The noise disappears	See table S10 ENGINE WHISTLING / UNIT BELT NOISE End of diagnosis
3	CHECKING SITE OF KNOCKING Carry out a test to locate the precise area from which the knocking is coming, using suitable equipment	OK	Move onto step 4
		The knocking is coming from the cylinder head	Move onto step 5
		The knocking is coming from the cylinder block/crankcase	Move onto step 4
4	CHECKING CRANKCASE KNOCK Carry out a test to identify the conditions in which the knocking from the crankcase occurs.	OK	Move onto step 5
		The knocking occurs with the engine cold, decreases with the engine hot and can be heard when releasing the accelerator.	Overhaul the engine, in particular check the condition of the pistons and replace them if necessary. Op. 1028H10 End of diagnosis
		The knocking occurs with the engine cold and increases during full acceleration with a long ratio.	Overhaul the engine: in particular, check the condition of the main bearings and replace them if necessary. Op. 1024A10 End of diagnosis
		The knocking is of a low intensity when cold but increases with the engine warm	Overhaul the engine: in particular, check the condition of the gudgeon pins and replace them. Op. 1028H60 End of diagnosis
		The knocking can be heard at all temperatures	Overhaul the engine: in particular, check the condition of the big end bearings and replace them if necessary Op. 1024A10 End of diagnosis
		The knocking can be heard at all temperatures and decreases when the clutch pedal is pushed.	Overhaul the engine and check the crankshaft end float. End of diagnosis
5	CHECKING TAPPET KNOCK If the car is not used frequently, an accentuated knocking sound may be heard from the tappets for a few minutes upon start up before gradually disappearing (see specific S.N.)	OK	Move onto step 6
5		Tappet knock persists	Move onto step 6
6	CHECKING CYLINDER HEAD Overhaul the cylinder head and, in particular, check the operation of the hydraulic tappets that the cams are not worn variable valve timing system camshaft clearane valves and springs	OK	Move onto step 7
		Cam worn or incorrect camshaft clearances	Restore or replace the components involved End of diagnosis
		Tappets noisy	Check hydraulic tappet operation (as per standard procedure) and replace any that are not working End of diagnosis
7	CHECKING CORRECT OPERATION Check that the fault is no longer present	OK	Incorrect selection of diagnostic procedure
7		Fault persists	Incorrect selection of diagnostic procedure

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Parts & tools for this job For 2000 Alfa Romeo 147

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