Engine - 6.7L Diesel
Engine
Pinpoint Tests
Pinpoint Test A: Low Oil Pressure
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
PINPOINT TEST A: LOW OIL PRESSURE
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A1 CHECK THE OIL PUMP PICKUP TUBE AND SCREEN FOR DAMAGE
- Check that the oil pump pickup tube and screen is not plugged, cracked or that the bolts are loose.
- Is the oil pump screen and pickup tube damaged or loose?
Yes
REPAIR as necessary. REFER to Oil Pump Screen and Pickup Tube Service and Repair.
No
GO to A2.
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A2 CHECK THE PISTON COOLING TUBES FOR DAMAGE OR MISSING
- Verify that all 8 piston cooling tubes are there and properly pointed at the piston under bottom.
- Is the piston cooling tubes damaged or missing?
Yes
REPAIR as necessary. REFER to Engine Engine - Disassembly.
No
GO to A3
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A3 CHECK THE OIL PUMP FOR DAMAGE
- Verify the oil pump is not damaged.
- Is oil pump damaged?
Yes
REPLACE the engine front cover. REFER to Engine Front Cover Engine Front Cover.
No
GO to A4.
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A4 CHECK THE CRANKSHAFT END PLAY
- Check the crankshaft end play. Refer to Crankshaft End Play Crankshaft End Play.
- Is the crankshaft end play within specification?
Yes
GO to A5.
No
REPAIR as necessary. REFER to Engine Engine - Disassembly.
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A5 CHECK CAMSHAFT JOURNAL-TO-BEARING CLEARANCE
- Check the camshaft journal-to-bearing clearance. Refer to Specifications.
- Is camshaft journal-to-bearing clearance within specification?
Yes
GO to A6.
No
REPAIR as necessary. REFER to Engine Engine - Disassembly.
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A6 CHECK FOR RESTRICTED OIL FLOW
- Verify the oil supply and return passages are not plugged and clean of debris.
- Is oil flow restricted?
Yes
REPAIR as necessary. REFER to Engine Engine - Disassembly.
No
GO to A7.
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A7 CHECK CRANKSHAFT MAIN BEARING JOURNAL-TO-BEARING CLEARANCE
- Check the crankshaft main bearing journal-to-bearing clearance. Refer to Specifications.
- Is crankshaft main bearing journal-to-bearing clearance within specification?
Yes
GO to A8.
No
REPAIR as necessary. REFER to Engine Engine - Disassembly.
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A8 CHECK CONNECTING ROD BEARING JOURNAL-TO-BEARING CLEARANCE
- Check the connecting rod bearing journal-to-bearing clearance. Refer to Specifications.
- Is connecting rod bearing journal-to-bearing clearance within specification?
Yes
The concern may have been caused by debris or an incorrect assembly. REPEAT the oil pressure test.
No
REPAIR as necessary.
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