ISC, ISCe, QSC8.3, ISL, ISLe3, ISLe4 and QSL9 Engines – Lubricating Oil Consumption Excessive

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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 Procedures
007-025, and


Crankcase ventilation system is plugged

Check and clean the crankcase breather and vent tube. Refer to Procedure
003-018 and


Lubricating oil does not meet specifications for operating conditions

Change the oil and filters. Refer to Procedures
007-037 and
007-013. Use the oil type recommended in Section V of the operation and maintenance manual.


Lubricating oil drain interval is excessive

Verify the correct lubricating oil drain interval. Refer to Section 2 in the Operation and Maintenance Manual, ISC and ISL Series Engines, Bulletin
4021428 or Operation and Maintenance Manual, QSC8.3 and QSL9 Engines, Bulletin


Air compressor is pumping lubricating oil into the air system

Check the air lines for carbon buildup and lubricating oil. Refer to Procedure


Lubricating oil cooler is leaking oil

Check the lubricating oil cooler for oil leaks. Refer to Procedure


Lubricating oil level is above specification

Check the oil level. Verify the dipstick calibration and oil pan capacity. Fill the system to the specified level. Refer to Procedure


Engine angularity during operation exceeds specification

Refer to Recreational Installation Directions for Marine Engines, Bulletin 3884649.


Turbocharger oil seal is leaking

Check the turbocharger compressor and turbine seals. Refer to Procedure


Valve seals are worn

Inspect the valve seals. Replace the valve seals, if necessary. Refer to Procedure


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 Procedure
001-043 and


Lubricating oil is contaminated with coolant or fuel

Refer to the Lubricating Oil Contaminated symptom tree.


Piston or piston rings are worn or damaged

Check for air intake system leaks. Check the pistons and piston rings for wear or damage. Refer to Procedure


Internal engine damage

Analyze the oil and inspect the filters to locate an area of probable damage. Refer to Procedure

Last Modified:  09-Apr-2007