N14 Base Engine Troubleshooting and Repair Manual – Lubricating Oil Consumption Excessive

Symptom Tree  t102

This is symptom tree t102
Cause Correction

Verify the oil consumption rate

Check the amount of oil added versus the mileage.


Lubricating oil leak (external)

Inspect the engine for external oil leaks. Tighten the capscrews, pipe plugs, and fittings. Replace gaskets, if necessary. Refer to the OEM specifications.


Crankcase ventilation system is plugged

Check and clean the crankcase breather and vent tube. Refer to Procedures 003-001.


Air compressor is pumping lubricating oil into the air system

Check the air lines for carbon buildup and lubricating oil. Refer to the Air Compressor is Pumping Excessive Lubricating Oil into the Air System symptom tree.


Turbocharger oil seal is leaking

Check the turbocharger compressor and turbine seals. Refer to Procedures 010-040 and 010-049.


Lubricating oil temperature is above specification

Refer to the Lubricating Oil Temperature Above Specification symptom tree.


Lubricating oil cooler is leaking

Check for lubricating oil in the coolant. Refer to the Lubricating or Transmission Oil in the Coolant symptom tree.


Lubricating oil is contaminated with coolant or fuel

Refer to the Lubricating Oil Contaminated symptom tree.


Lubricating oil dipstick calibration is not correct

Check the dipstick calibration. Refer to Procedure 007-009.


Lubricating oil does not meet specifications for operating conditions

Change the oil and filters. Refer to Procedure 007-013.


Lubricating oil drain interval is excessive

Verify the correct lubricating oil drain interval. Refer to Section 2 in the Operation and Maintenance Manual, N14 Plus, Bulletin 3666136.


Step timing control system not switching to advanced timing mode

Inspect step timing control operation. Refer to Procedure 006-045.


Piston rings are not seated correctly (after an engine rebuild or piston installation)

Check blowby. Refer to Section 14. If blowby is excessive, check the piston rings for correct seating. Refer to Procedures 001-043 and 001-047.


Cylinder liner, pistons, or piston rings are worn or damaged

Check the pistons, piston rings, and cylinder liner. Refer to Procedures 001-043, 001-047, and 001-028.

Last Modified:  13-Jan-2004