Symption | Suspect area | Remedy |
Engine misfire with abnormal internal lower engine noises | ● Worn crankshaft bearings ● Loose or out of specification engine flywheel | ● 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. | |
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 (Check and compare with known good vehicle to determine normal condition.) | 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 camshaft 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 is not cranked. Crankshaft does 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 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 connecting rods. 2. Repair as required. | |
Broken crankshaft | 1. Inspect crankshaft. 2. Repair as required. |
