Symption | Suspect area | Remedy |
Engine misfire with abnormal internal lower engine noises. | Worn crankshaft bearings Loose or improperly engine filwheel | Replace the crankshaft and bearings as required. Repair or replace the flywheel as required. |
Worn piston rings (Oil consumption may or may not cause the engine to misfire.) | Inspect the cylinder for a loss of compression. Repair or replace as required. | |
Worn crankshaft thrust bearings | Replace the crankshaft and bearings as required | |
Engine misfire with abnormal valve train noise. | Stuck valves. (Carbon buidup on the valve stem) | Repair or replace as required |
Excessive worn or mis-aligned timing chain | Replace the timing chain and sprocket as required. | |
Worn camshaft lobes. | Replace the camshaft and valve lifters. | |
Engine misfire with coolant consumption | ● Faulty cylinder head gasket or other damage to the cylinder head and engine block cooling system. ● Coolant consumption may or may not cause the engine to overheat. | ● Inspect the cylinder head and engine block for damage to the coolant passages and/or a faulty head gasket. ● Repair or replace as required. |
Engine misfire with excessive oil consumption | Worn valves, guides and/or valve stem oil seals. | Repair or replace as required. |
Worn piston rings. (Oil consumption may or may not cause the engine to misfire) | ● Inspect the cylinder for a loss of compression. ● Repair or replace as required. | |
Engine noise on start-up, but only lasting a few seconds. | Incorrect oil viscosity | ● Drain the oil. ● Install the correct viscosity oil. |
Worn crankshaft thrust bearing. | ● Inspect the thrust bearing and crankshaft. ● Repair or replace as required. | |
Upper engine noise, regardless of engine speed. | Low oil pressure | Repair or replace as required. |
Broken valve spring. | Replace the valve spring. | |
Worn or dirty valve lifters. | Replace the valve lifters. | |
Stetched or broken timing chain and/or damaged sprocket teeth. | Replace the timing chain and sprockets. | |
Worn timing chain tensioner, if applicable. | Replace the timing chain tensioner as required. | |
Worn camshaft lobes. | ● Inspect the camshaft lobes. ● Replace the timing camshaft and valve lifters as required. | |
Worn valve guides or valve stems. | Inspect the valves and valve guides, then repair or replace as required. | |
Stuck valves. (Carbon on the valve stem or valve seat may cause the valve to stay open. | Inspect the valves and valve guides, then repair or replace as required. | |
Worn drive belt, idler, tensioner and bearing. | Replace as required | |
Lower engine noise, regardless of engine speed | Low oil pressure | Repair or required. |
Loose or damaged flywheel. | Repair or replace the flywheel. | |
Damaged oil pan, contacting the oil pump screen. | ● Inspect the oil pan. ● Inspect the oil pump screen. ● Repair or replace as required. | |
Oil pump screen loose, damaged or restricted. | ● Inspect the oil pump screen. ● Repair or replace as required. | |
Excessive piston-to-cylinder bore clearance. | ● Inspect the piston, piston pin and cylinder bore. ● Repair or replace as required. | |
Excessive piston pin-to-piston clearance | ● Inspect the piston, piston pin and the connecting rod. ● Repair or replace as required. | |
Excessive connecting rod bearing clearance | Inspect the following components and repair or replace as required. ● The connecting rod bearings. ● The connecting rods. ● The crankshaft pin journals. | |
Excessive crankshaft bearing clearance | Inspect the following components, and repair or replace as required. ● The crankshaft bearings. ● The crankshaft main journals. ● The cylinder block | |
Incorrect piston, piston pin and connecting rod installation | ● Verify the piston pins and connecting rods are installed correctly. ● Repair as required. | |
Engine noise under load | Low oil pressure | Repair or replace as required. |
Excessive connecting rod bearing clearance | Inspect the following components and repair or replace as required : ● The connecting rod bearings. ● The connecting rods. ● The crankshaft | |
Excessive crankshaft bearing clearance | Inspect the following components, and repair or replace as required. ● The crankshaft bearings. ● The crankshaft main journals. ● The cylinder block. | |
Engine will not crank-crankshaft will not rotate | Hydraulically locked cylinder ● Coolant/antifreeze in cylinder. ● Oil in cylinder. ● Fuel in cylinder | 1. Remove spark plugs and check for fluid. 2. Inspect for broken head gasket. 3. Inspect for cracked engine block or cylinder head. 4. Inspect for a sticking fuel injector and/or leaking fuel regulator. |
Broken timing chain and/or timing chain and/or timing chain gears. | 1. Inspect timing chain and gears. 2. Repair as required. | |
Material in cylinder ● Broken valve ● Piston material ● Foreign material | 1. Inspect cylinder for damaged components and/or foreign materials. 2. Repair or replace as required. | |
Seized crankshaft or connecting rod bearings. | 1. Inspect crankshaft and connecting rod bearing. 2. Repair as required. | |
Bent or broken connecting rod. | 1. Inspect connecing rods. 2. Repair as required. | |
Broken crankshaft | 1. Inspect crankshaft. 2. Repair as required. |
