Normal Operation

Oil is drawn into the oil pump through the oil pump screen and pickup tube in the sump of the oil pan. Oil is pumped through the oil cooler where it is cooled on the left rear side of the upper oil pan then enters the oil filter where it is filtered then distributed to the crankshaft main journals, camshaft, turbocharger and to both cylinder heads and front cover. From the main journals, the oil is routed through cross-drilled passages in the crankshaft to lubricate the connecting rod bearings. Controlled leakage through the crankshaft main bearings and connecting rod bearings is slung radially outward to cool and lubricate the cylinder walls as well as the entire connecting rod, piston and piston ring assembly. The pistons are also cooled by the piston cooling tubes. The oil spray bars lubricate the rocker arm assemblies on the cylinder heads. The camshaft lobes and valve tappets are lubricated by splash created through valve train operation.

This pinpoint test is intended to diagnose the following:

• Excessive crankshaft end play
• Excessive main bearing clearance
• Excessive connecting rod bearing clearance
• Excessive camshaft bearing clearance
• Loose oil galley plugs
• Oil pump screen and pickup tube
• Restricted oil flow passages
• Worn or damaged oil pump
• Damaged or missing piston cooling tube