72763 - S01 ENGINE KNOCK

The engine makes a cyclical noise with the intensity varying according to the load which is noticeable during brisk acceleration and when using long ratios.

STEP	OPERATIONS TO BE CARRIED OUT	TEST RESULTS
1	CHECK USING DIAGNOSTIC EQUIPMENT	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Connect the diagnostic equipment to the diagnostic socket and check. That there are no faults in the engine management control unit	Move on to Step	Error detected in the control unit	Continue following the instructions for the diagnostic equipment
2	AUXILIARY UNITS CHECK	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Disconnect the services belt and check whether the noise disappears. do not let the engine run for too long with the belt disconnected.	Move on to Step	The noise disappears: fault due to auxiliary components	Locate the auxiliary component where the noise is coming from and eliminate the noise
3	GENERAL GEARBOX/DIFFERENTIAL UNIT CHECK	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Repeat the test described in step 2 pressing the clutch and check whether the noise disappears. do not let the engine run for too long with the belt disconnected.	Move on to Step	The noise only occurs with the clutch engaged: fault due to the clutch/gearbox assembly	Check the cause of the noise, if necessary, replace the clutch or overhaul the gearbox
4	KNOCK LOCATION CHECK	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Carry out a test to locate the area where the knocking is coming from using special equipment.	Move on to Step	1. The knocking is coming from the cylinder head	Move on to Step
			2. The knocking is coming from the cylinder block/crankcase	Move on to Step
5	CYLINDER BLOCK/CRANKCASE KNOCK CHECK	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Carry out a test to identify the circumstances in which the cylinder block/crankcase knock occurs.	Move on to Step	1. The knocking occurs with the engine cold and decreases when warm, when accelerating it is noticeable on overrun	Overhaul the engine, in particular:1. Check the condition of the pistons and, if necessary, replace them
			2. The knocking occurs with the engine cold and increases when accelerating in long ratios	2. Check the condition of the crankshaft bearings and, if necessary, replace them
			3. The knocking is not intense when cold, but increases when the engine is warm	3. Check the condition of the gudgeon pins and, if necessary, replace them
			4. The knocking is heard at all temperatures	4. Check the condition of the big end bearings and, if necessary, replace them
			5. The knock is heard at all temperatures and decreases when the clutch pedal is pressed	5. Check the crankshaft endfloat
6	VALVE CLEARANCE CHECK	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Check the tappet clearance	Move on to Step	Clearance not correct	Adjust the valve clearance
7	CYLINDER HEAD CHECK	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Overhaul the cylinder head and, in particular, check: Injectors Tappet operation No cam wear Cam axis clearance Valves and springs	Move on to Step	Cam wear or incorrect camshaft clearance	Repair or replace the components concerned
8	CHECK ON CORRECT OPERATION	ALL OK	PROBLEMS ENCOUNTERED	ACTION
	Check that the fault is no longer present