Cummins ISX11.9 CM2250 – Service Manual 007-999   Lubricating Oil System – Overview

WARNING  Some state and federal agencies have determined that used engine oil can be carcinogenic and can cause reproductive toxicity. Avoid inhalation of vapors, ingestion, and prolonged contact with used engine oil. If not reused, dispose of in accordance with local environmental regulations.

WARNING  To reduce the possibility of personal injury, avoid direct contact of hot oil with your skin.

Cummins Inc. recommends the use of a high-quality SAE 15W-40 heavy-duty engine oil, such as Valvoline® Premium Blue®, which meets the API CI-,  and API CH-4.

The API service symbols are shown in the accompanying illustration.

1. The upper half of the symbols display the appropriate oil categories.
2. The lower half contains words to describe oil energy-conserving features.
3. The center section identifies the SAE oil viscosity grade.

CAUTION  Limited use of low-viscosity lubricating oils, such as 10W-30, can aid in starting the engine and providing sufficient lubricating oil flow at ambient temperatures below -5°C [23°F] as shown in the illustration. However, the continuous use of low-viscosity lubricating oils can decrease engine life.

Lubricating oil viscosity must be chosen according to the typical climate conditions experienced by the user. Use of 15W-40 is recommended for the best engine durability at higher ambient temperature. For cold temperature conditions, 10W-30 or 5W-30 viscosity can be used for easier starting, improved lubricating oil flow, and improved fuel economy.

Special “break-in” engine lubricating oils are not recommended for new or rebuilt Cummins® engines. In general, use the same lubricating oil during break-in as that used in normal operation. Synthetic or partially synthetic engine lubricating oils, however, can not be used during break-in of a new or rebuilt engine. To make sure the piston rings seat properly, use a high quality petroleum-based engine lubricating oil during the first engine lubricating oil drain period.

As the engine lubricating oil becomes contaminated, essential lubricating oil additives are depleted. Lubricating oils protect the engine as long as these additives are functioning properly. Progressive contamination of the lubricating oil between lubricating oil and filter change intervals is normal. The amount of contamination will vary depending on the operation of the engine, kilometers or miles on the lubricating oil, fuel consumed, and new lubricating oil added.

Extending lubricating oil and filter change intervals beyond the recommendations will decrease engine life because of factors such as corrosion, deposits, and wear.

Use the lubricating oil drain chart in this section to determine which lubricating oil drain interval to use for a particular application.

The demand flow and cooling lubricating system incorporates a lubricating oil pump (1) with a pressure-sensitive regulator circuit (2) and a high-pressure relief valve (3).

When the diagnosing lubricating system malfunctions, check all obvious items related to oil pressure, such as gauges, high and low oil level, excessive oil contamination, and oil viscosity.

High lubricating oil pressure occurs after the engine is first started in cold weather. Cold-start oil pressure typically will be approximately 689 to 827 kPa [100 to 120 psi]. If the pressure regulator plunger is operating properly, the oil pressure should drop back to approximately 414 kPa [60 psi] when normal engine operating temperature is reached.

The engine will have high oil pressure at normal operating temperature if the lubricating oil pressure regulator valve sticks in the closed position.

Check the regulator for freedom of movement. Refer to Procedure 007-015 in Section 7.

Low lubricating oil pressure (or no oil pressure) can be caused by several lubricating system-related malfunctions. To begin the investigation, determine the engine operating conditions when the low pressure was first observed. The following are potential conditions of low lubricating oil pressure:

• Following a service interval
• At idle only
• Operating on a steep grade
• Operating in rough seas.

High lubricating oil level can cause low oil pressure. If the oil level is high enough for the connecting rods to dip into the oil while operating, the oil can become aerated, resulting in low oil pressure.

Low oil level will not normally appear as low oil pressure. Typically, it will appear as an intermittent loss of oil pressure when rounding a corner or operating on a steep grade. This condition exists when the oil level is extremely low and the suction tube can not pick up oil during all modes of operation.

A plugged lubricating oil filter will cause a gradual loss of oil pressure by approximately 69 kPa [10 psi]. The pressure will return to normal when the filter bypass valve opens. If not corrected, this will result in severe engine wear, as the engine is running on unfiltered oil when the bypass valve is open.

Check the lubricating oil gauge and sending unit, to make sure they are operating correctly, by verifying the pressure with a manual gauge.

A loose lubricating oil suction tube, damaged gasket, or crack in the suction tube can cause a loss of prime for the oil pump. The engine will have low pressure or no oil pressure during starting, followed by normal oil pressure.

A steady decrease in oil pressure over a long period can be an indication of worn bearings or excessive lubricating oil pump wear.

Though similar in design and appearance, there are many variations of the lubricating oil pump. Before installing a new lubricating oil pump, make sure that the pump is correct for your engine.

Use the following procedure for removal and installation procedures. Refer to Procedure 007-031 in Section 7. See QuickServe™ Online to determine the correct lubricating oil pump part number.

CAUTION  Using diluted oil can cause severe engine damage.

Check the condition of the lubricating oil:

• Thin, black oil is an indication of fuel in the oil
• Milky discoloration is an indication of coolant in the oil.

Coolant in the oil can be caused by:

• Expansion plugs leaking
• Oil cooler element leaking
• Damaged cylinder head or gasket
• Cracked engine block
• Casting porosity.

A damaged lubricating oil cooler element  will allow mixing of the fluids. Refer to Procedure 007-003 in Section 7.

While operating, the oil pressure will be higher than coolant pressure. A leak in the oil cooler will show as oil in the coolant.

However, following an engine shutdown, the residual pressure in the coolant system can cause coolant to seep through the leak path into the oil.

If the oil cooler element ruptures, the oil pressure will force oil into the cooling system.

Oil in the coolant should be visible when the radiator cap is removed. Refer to Procedure 007-003 in Section 7.

To check for leaks, pressurize the cooling system to 140 kPa [20 psi]. With the system pressurized, remove the following components and inspect for leaks:

• Rocker lever cover. Refer to Procedure 003-011 in Section 3. Leaks indicate a cracked cylinder head.
• Lubricating oil drain plug. Refer to Procedure 007-037 in Section 7. Leaks indicate a malfunctioning oil cooler, cylinder head gasket, or a cracked cylinder head or block.

Coolant in the lubricating oil can be caused by a damaged cylinder head gasket, or a cracked cylinder head or block.

Remove the cylinder head and gasket. Refer to Procedure 002-004 in Section 2.

Inspect for cracks or any other damage.

Fuel dilution of the lubricating system is generally due to the injector, but may also be due to internal damage to the high-pressure pump.

Incomplete combustion in the cylinders can result in unburned fuel draining into the oil pan.

This condition can be caused by a leaking injector or reduced compression caused by inadequate piston ring sealing.

An increase in white exhaust smoke during the first start of the day is a symptom that an injector is leaking.

An injector leak will also cause the engine to run rough and have low power.

Remove and repair, or replace leaking injectors. Refer to Procedure 006-026 in Section 6.

The o-rings in the injectors can be inspected for cracks or wear. A missing or damaged o-ring in an injector can result in improper disbursement of fuel into the cylinder.

Also, a poor seal between the injector and the high-pressure transfer tube can also cause the injector o-rings to malfunction or leak into the top of the cylinder head.

Various gaskets, seals, and plugs are used to contain the lubricating oil. Most leaks can be identified during routine inspections of the engine and vehicle.

Worn or damaged seals in the turbocharger can also allow oil to leak into the charge air cooler system and be burned in the engine.

This condition can be verified by removing the air crossover tube or charge-air cooler tubing and looking for oil. Refer to Procedure 010-027 in Section 10.

NOTE: If the engine experiences a turbocharger malfunction, or any other occasion where oil or debris is put into the charge-air cooler, the charge-air cooler must be cleaned.

Inadequate sealing of the piston rings will result in oil being blown out of the breather tube and/or consumed by the engine. Refer to Procedure 014-010 in Section 14.

Lubricating oil can also be lost through a worn or malfunctioning air compressor. Look for carbon buildup in the air line from the compressor to the air tank.

Also, a damaged air compressor head gasket or cylinder head gasket can allow oil to leak into the coolant or coolant to leak into the oil during a hot shutdown.