Engine Diagnostic Trouble shooting

Symptom/Diagnosis	Suspect Area/Parts	Action/Remedy
Engine misfire w/ abnormal lower engine noise	1)Worn crankshaft bearing. 2)Loose or improperly engine drive plate 3)Worn piston ring (oil consumption may or may not cause the engine to misfire) 4)Worn crankshaft thrust bearing.	1)Replace the crankshaft and bearing as required. 2)Repair or replace the drive plate 3)Inspect the cylinder for the loose of compression.repair or replace. 4)Replace the crankshaft & bearing
Engine misfire w/ abnormal valve train noise.	1)stuck valves (carbon build up on the valve stem. 2)Excessive worn or misaligned timing chain. 3)Worn camshaft lobes.	1)Repair or Replace 2)Replace the timing chain and sprocket. 3)Replace the camshaft & valve lifters.
Engine misfire w/ coolant consumption.	1)Faulty cylinder head gasket or other damage of cylinder head or engine block cooling system.	1)Inspect the cylinder head & gasket or coolant passages from engine block.
Excessive oil consumption w/ engine misfire.	1)Worn valve, guides or valve stem. 2)Worn piston ring.(oil consumption may/not cause the engine to misfire).	1)Repair or replace . 2)Inspect the cylinder for loose compression, repair or replace.
Engine noise on start up but only in few second.	1)Incorrect oil viscosity . 2)Worn thrust bearing.	1)change oil w/correct oil viscosity. 2)Inspect thrust bearing repair or replace if necessary.
Regardless of engine speed,upper engine noise occurs.	1)Low oil pressure 2)Deform or clogged valve lifter. 3)damage valve spring. 4)Worn camshaft lobes. 5)Worn timing chain tensioner. 6)Stretched or broken timing chain or damage sprocket teeth. 7)Worn valve stem or guides. 8)Stuck valves.(carbon deposit on valve stem or valve seat can cause the valve to stay open. 9)Worn drive belt, idler, tensioner & bearing.	1)check oil passages or replace oil pump. 2)replace. 3)replace. 4)Inspect the camshaft lobes. 5)Replace the timing chain tensioner if necessary. 6)Replace timing chain & sprocket. 7)Inspect and repair or replace. 8)Inspect valves & guides then repair as required. 9)Replace as required.  more study please leave comment