S01 ENGINE KNOCK - Alfa - 156 - eLearn

3233149 - S01 ENGINE KNOCK

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

0	PRELIMINARY CHECKS	All OK	Problems met	Operation
		Results of the tests
	Disconnect the services belt and check whether the noise disappears. WARNING: do not let the engine run for long with the belt disconnectedPress the clutch and check whether the noise disappears	Continue to Step 1	The noise disappears with the services belt disconnected	See table S10
		Continue to Step 1	The noise only occurs with the clutch engaged	See table S20
1	CHECK WITH DIAGNOSTIC EQUIPMENT	All OK	Problems met	Operation
	Connect the diagnostic equipment (Examiner or other instruments) to the diagnostic socket Check: that there are no faults in the engine management control unit plausibility of all the parameters	Continue to Step 2	An error is detected in the control unit	Continue according to the instructions for the diagnostic equipment
		Continue to Step 2	Lack of dialogue with the control unit	Restore the connection between the engine management control unit and the diagnostic connector See E5050 DIESEL ENGINES ELECTRONIC MANAGEMENT
2	KNOCKING LOCATION CHECK	All OK	Problems met	Operation
	Carry out a test to locate the precise area from which the knocking is coming (if necessary, use suitable equipment)	Continue to Step 3	the knocking is not located:	Continue to Step 3
			the knocking is coming from the cylinder head	Continue to Step 4
			the knocking is coming from the cylinder block/crankcase	Continue to Step 3
3	KNOCKING CONDITION CHECK	All OK	Problems met	Operation
	Carry out a test to identify the conditions in which the knocking from the cylinder block/crankcase occurs	The knocking does not occur: Continue to Step 4	The knocking occurs with the engine cold and decreases during acceleration	Overhaul the engine: in particular, check the condition of the pistons and replace them (see ENGINE OVERHAUL, Subassembly 1028)
			The knocking occurs with the engine cold and increases during acceleration	Overhaul the engine: in particular, check the condition of the main bearings and replace them: Op. 1024A10
			The knocking increases with the engine warm	Overhaul the engine: check the condition of the gudgeon pins and replace them (see ENGINE OVERHAUL, Subassembly 1028)
			The knocking disappears when the clutch is pressed	Overhaul the engine: check the crankshaft end float (see ENGINE OVERHAUL, Subassembly 1004)
4	VALVE CLEARANCE CHECK	All OK	Problems met	Operation
	Check that the valve tappet clearance is correct. Op. 1036H14	Continue to Step 5	Clearance not correct	Restore the correct valve clearance. Op. 1036H18
5	CYLINDER HEAD CHECK	All OK	Problems met	Operation
	Overhaul the cylinder and, in particular, check that the cams are not worn that the camshaft clearances are correct the operation of the tappets	Continue to Step 6	Cam worn or camshaft clearances incorrect	Restore or replace the components involved Op. 1036B10
6	CHECK 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'