MBE 900 – Section 15.14 Low Oil Pressure

Section 15.14
Low Oil Pressure

There are several causes for low oil pressure. These probable causes are:‪

• Improper Engine Oil Level
• Improper Lubricating Oil Viscosity
• Lubricating Oil Diluted with Fuel or Engine Coolant
• Faulty Oil Pressure Gauge Sensor
• Obstructed Oil Pressure Gauge Line
• Restricted Oil Cooler
• Defective Bypass Valve
• Defective Pressure Relief Valve
• Defective Pickup Screen Tube and Screen Assembly
• Defective Crankshaft Main Bearing Shells
• Defective Oil Pump Assembly

Section 15.14.1
Troubleshooting Procedure for Improper Engine Oil Level

To determine if improper engine oil level is causing low oil pressure, check the engine oil level listed in Table "Lubricating Oil Capacity" .‪

1. If the engine oil level is correct, check lubricating oil viscosity; refer to "15.14.3 Troubleshooting Procedure for Improper Lubricating Oil Viscosity" .
2. If the engine oil level is incorrect, refer to "15.14.2 Low Engine Oil Level Resolution" .

Description ‪	4–Cylinder Engines ‪	6–Cylinder Engines ‪
Oil Fill Capacity*‪	15.8 L (16.7 qt.)‪	29.0 L (30.6 qt.)‪

* In standard pan, including oil filter.

Section 15.14.2
Low Engine Oil Level Resolution

Perform the following steps for low engine oil level:‪

1. Fill engine oil pan to correct level listed in Table "Lubricating Oil Capacity" .
2. Verify low engine oil resolution; refer to "15.14.2.1 Test for Proper Engine Oil Level" .

Section 15.14.2.1
Test for Proper Engine Oil Level

Perform the following steps to determine if properly filled oil pan has resolved low oil pressure:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and vary engine speed between 1800-2100 rpm.
2. Measure engine oil pressure.
   1. If the oil pressure is 241 kPa (35 psi) or more, no further troubleshooting is required. Shut down the engine.
   2. If the oil pressure at rated speed is less than 241 kPa (35 psi), shut down the engine. Check lubricating oil viscosity; refer to "15.14.3 Troubleshooting Procedure for Improper Lubricating Oil Viscosity" .

Section 15.14.3
Troubleshooting Procedure for Improper Lubricating Oil Viscosity

To determine if improper lubricating oil viscosity is causing low oil pressure, perform the following steps:‪

1. Acquire a lubricating oil sample from the engine oil pan.
2. Submit oil sample for an ASTM test analysis.
   1. If engine oil sample meets ASTM specifications, check to determine if lubricating oil is diluted with fuel or coolant; refer to "15.14.5 Troubleshooting Procedure for Lubricating Oil Diluted with Fuel or Engine Coolant" .
   2. If engine oil sample did not meet ASTM specifications, refer to "15.14.4 Lubricating Oil Replacement" and DDC publication Lubricating Oil, Fuel, and Filters (7SE270).

Section 15.14.4
Lubricating Oil Replacement

Perform the following steps to replace engine oil:‪

1. Drain and refill engine with new lubricating oil. Engine oil capacities are listed in Table "Lubricating Oil Capacity" .
2. Verify lubricating oil replacement; refer to "15.14.4.1 Test Engine with Replaced Lubricating Oil" .

Section 15.14.4.1
Test Engine with Replaced Lubricating Oil

Perform the following steps to determine if replaced lubricating oil resolved low oil pressure:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run engine at rated speed.
2. Measure engine oil pressure.
   1. If the oil pressure is 241 kPa (35 psi) or more, no further troubleshooting is required. Shut down the engine.
   2. If the oil pressure at rated speed is less than 241 kPa (35 psi), shut down the engine. Check the lubricating oil for fuel and engine coolant dilution; refer to "15.14.5 Troubleshooting Procedure for Lubricating Oil Diluted with Fuel or Engine Coolant" .

Section 15.14.5
Troubleshooting Procedure for Lubricating Oil Diluted with Fuel or Engine Coolant

To determine if lubricating oil diluted with fuel or engine coolant is causing low oil pressure, perform the following steps:‪

1. Acquire a lubricating oil sample from the engine oil pan.
2. Visually examine lubricating oil sample for presence of engine coolant or fuel.
   1. If coolant or fuel are not present, check for a faulty oil pressure gauge; refer to "15.14.7 Troubleshooting Procedure for Faulty Oil Pressure Gauge Sensor" .
   2. If coolant or fuel are present, refer to "15.14.6 Contaminated Lubricating Oil Resolution" .

Section 15.14.6
Contaminated Lubricating Oil Resolution

Perform the following steps to resolve contaminated lubricating oil:‪

1. If coolant is present, consider head gasket replacement and repair as required.
2. If fuel is present, consider fuel nozzle replacement and repair as required.
3. Drain engine oil pan.
4. Refill engine crankcase with new oil.
5. Verify lubricating oil replacement; refer to "15.14.6.1 Test Replaced Lubricating Oil" .

Section 15.14.6.1
Test Replaced Lubricating Oil

To determine if replaced lubricating oil resolved low oil pressure, perform the following:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run the engine at rated speed, if the oil pressure is 241 kPa (35 psi) or more, no further troubleshooting is required.
2. If the oil pressure at rated speed is less than 241 kPa (35 psi), shut down the engine. Check for faulty oil pressure gauge sensor; refer to "15.14.7 Troubleshooting Procedure for Faulty Oil Pressure Gauge Sensor" .

Section 15.14.7
Troubleshooting Procedure for Faulty Oil Pressure Gauge Sensor

To determine if a faulty oil pressure gauge sensor is causing low oil pressure, perform the following steps:‪

1. Install the Diagnostic Data Reader (DDR).

   PERSONAL INJURY ‪
   To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

2. Start and vary the engine speed between 1800 - 2100 rpm.
3. Visually examine the DDR for oil pressure reading.
   1. If the oil pressure is greater than or equal to 241 kPa (35 psi) at rated speed, shut down the engine. No further troubleshooting is required.
   2. If the oil pressure is less than 241 kPa (35 psi) at rated speed, shut down the engine; refer to "15.14.8 Oil Pressure Gauge Sensor Replacement" .

Section 15.14.8
Oil Pressure Gauge Sensor Replacement

Perform the following steps to replace the oil pressure gauge sensor:‪

1. Remove and replace the oil pressure gauge sensor; refer to OEM guidelines.
2. Verify oil pressure gauge sensor replacement; refer to "15.14.8.1 Test Replaced Oil Pressure Gauge Sensor"

Section 15.14.8.1
Test Replaced Oil Pressure Gauge Sensor

To determine if replaced oil pressure gauge sensor resolved the low oil pressure concern, perform the following:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run the engine at rated speed , if the oil pressure is 241 kPa (35 psi) or more, no further troubleshooting is required.
2. If the oil pressure at rated speed is less than is 241 kPa (35 psi), shut down the engine. Check for an obstructed oil pressure gauge line; refer to "15.14.9 Troubleshooting Procedure for Oil Pressure Gauge Line Obstructed" .

Section 15.14.9
Troubleshooting Procedure for Oil Pressure Gauge Line Obstructed

To determine if an oil pressure gauge line obstruction is causing low oil pressure, perform the following steps:‪

1. Disconnect oil gauge line from oil pressure gauge; refer to OEM guidelines.
2. Visually inspect oil gauge line for obstructions.
   1. If no obstructions are found, check to determine if rocker arm shaft plugs are missing (new or rebuilt engines only).
   2. If obstructions are found, refer to "15.14.10 Obstructed Oil Pressure Gauge Line Repair" .

Section 15.14.10
Obstructed Oil Pressure Gauge Line Repair

Perform the following steps to resolve oil pressure gauge line obstructions:‪

1. Remove oil pressure gauge line; refer to OEM guidelines.
2. Clean oil gauge line by soaking in cleaning solution for five minutes.
3. Blow out residue contamination in oil gauge line with compressed air.
4. Install cleaned oil gauge line; refer to OEM guidelines.
5. Verify oil gauge line repair; refer to "15.14.10.1 Test the Engine with Repaired Oil Gauge Line" .

Section 15.14.10.1
Test the Engine with Repaired Oil Gauge Line

To determine if repaired oil pressure gauge line resolved low oil pressure, perform the following steps:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run the engine at rated speed. If the oil pressure at rated speed is 241 kPa (35 psi) or more, no further troubleshooting in required. Shut down the engine.
2. If the oil pressure at rated speed is less than 241 kPa (35 psi), shut down the engine. Check for restricted heat exchanger; refer to "15.14.11 Troubleshooting Procedure for Restricted Heat Exchanger" .

Section 15.14.11
Troubleshooting Procedure for Restricted Heat Exchanger

To determine if a restricted heat exchanger is causing low oil pressure, perform the following steps:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run the engine at rated speed.
2. Run the engine at rated speed with a no-load condition for approximately five minutes, allowing the engine coolant to reach normal operating range 88-96°C (190-205°F).
   1. If the oil temperature sensor is indicating a lubricating oil temperature less than or equal to 110°C (230°F), shut down the engine and check for a defective oil filter bypass valve; refer to "15.14.13 Troubleshooting Procedure for Defective Oil Filter Bypass Valve" .
   2. If the oil temperature sensor is indicating a lubricating oil temperature greater than 110°C (230°F), shut down the engine and repair heat exchanger; refer to "15.14.12 Heat Exchanger Repair" .

Section 15.14.12
Heat Exchanger Repair

Perform the following steps to repair the heat exchanger:‪

1. Remove the heat exchanger; refer to "3.6.1 Heat Exchanger Removal" .
2. Clean the heat exchanger before sludge hardens. Flush oil passages with clean, hot water.
3. Inspect the heat exchanger for damage.
4. Install repaired heat exchanger; refer to "3.6.2 Heat Exchanger Installation" .
5. Verify repair of heat exchanger; refer to "15.14.12.1 Test Engine with Repaired Heat Exchanger" .

Section 15.14.12.1
Test Engine with Repaired Heat Exchanger

Perform the following steps to determine if heat exchanger repair resolved low oil pressure:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run the engine at rated speed.
2. Run the engine through its operating range with no-load condition for approximately five minutes, allowing the engine coolant to reach normal operating range, 88-96°C (190-205°F).
   1. If the DDR indicates 241 kPa (35 psi) or more at rated speed, shut down the engine and disconnect the DDR. No further troubleshooting is required.
   2. If the DDR indicates less than 241 kPa (35 psi) at rated speed, shut down the engine and disconnect the DDR. Check for defective oil filter bypass valve; refer to "15.14.13 Troubleshooting Procedure for Defective Oil Filter Bypass Valve" .

Section 15.14.13
Troubleshooting Procedure for Defective Oil Filter Bypass Valve

To determine if a defective oil filter bypass valve is causing low oil pressure, perform the following steps:‪

1. Remove the oil filter cover and element; refer to "3.5.1 Oil Filter Element Replacement" .
2. Inspect the oil filter bypass valve components.
   1. If no damage is found with the oil filter housing bypass valve components, check for defective pressure relief valve; refer to "15.14.14 Troubleshooting Procedure for Defective Oil Pump Pressure Relief Valve" .
   2. If damage is found with the oil filter housing bypass valve bore, replace housing. Refer to "3.4.1 Oil Filter Housing Removal" .

Section 15.14.14
Troubleshooting Procedure for Defective Oil Pump Pressure Relief Valve

To determine if a defective oil pump pressure relief valve is causing low oil pressure, perform the following steps:‪

1. Remove the oil pump pressure relief valve.
2. Inspect the oil pump pressure relief valve.
   1. If the relief valve moves freely in the valve body, reinstall the oil pressure relief valve. Check the pickup tube and screen assembly for defects.
   2. If the relief valve will not move freely in the valve body, refer to "15.14.15 Oil Pump Pressure Relief Valve Repair" .

Section 15.14.15
Oil Pump Pressure Relief Valve Repair

Perform the following steps to repair the oil pump pressure relief valve:‪

1. Disassemble the pressure relief valve and replace damaged components.
2. Assemble and install the pressure relief valve.
3. Verify repair of the pressure relief valve; refer to "15.14.15.1 Test Engine with Repaired Oil Pump Pressure Relief Valve" .

Section 15.14.15.1
Test Engine with Repaired Oil Pump Pressure Relief Valve

Perform the following steps to determine if repaired oil pump pressure relief valve resolved low oil pressure:‪

1. Install the DDR.

   PERSONAL INJURY ‪
   To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

2. Start and run engine speed at rated speed.
3. Visually examine the DDR for oil pressure reading.
   1. If the DDR indicates 241 kPa (35 psi) or more at rated speed, shut down the engine and disconnect the DDR. No further troubleshooting is required.
   2. If the DDR indicates less than 241 kPa (35 psi) at rated speed, shut down the engine and disconnect the DDR. Check for defective pickup tube and screen assembly; refer to "15.14.16 Troubleshooting Procedure for Defective Pickup Screen Tube and Screen Assembly" .

Section 15.14.16
Troubleshooting Procedure for Defective Pickup Screen Tube and Screen Assembly

To determine if a defective pickup screen tube or screen assembly is causing low oil pressure, perform the following steps:‪

1. Remove pickup screen tube and screen assembly. Refer to "3.3.1 Oil Pump Removal" .
2. Visually inspect pickup screen tube and screen assembly.
   1. If no tube stress cracks, twisted screen tube, or cracked flange are found, check for defective crankshaft main bearing shells; refer to "15.14.18 Troubleshooting Procedure for Defective Crankshaft Main Bearing Shells" .
   2. If stress cracks, twisted screen tube, or cracked flange are found, refer to "15.14.17 Pickup Screen Tube and Screen Assembly Replacement" .

Section 15.14.17
Pickup Screen Tube and Screen Assembly Replacement

Perform the following steps to replace the pickup screen tube and screen assembly:‪

1. Replace all damaged components identified during inspection and install. Refer to "3.3.2 Oil Pump Installation" .
2. Verify replacement to pickup screen tube and screen assembly; refer to "15.14.17.1 Test Engine with Replaced Pickup Screen Tube and Screen Assembly" .

Section 15.14.17.1
Test Engine with Replaced Pickup Screen Tube and Screen Assembly

Perform the following steps to determine if a replaced pickup screen tube or screen assembly resolved low oil pressure:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run the engine speed at rated speed.
2. Visually examine oil pressure reading.
   1. If the oil pressure at rated speed is 241 kPa (35 psi) or more, no further troubleshooting is required.
   2. If the oil pressure at rated speed is less than 241 kPa (35 psi), check for defective crankshaft main bearing shells; refer to "15.14.18 Troubleshooting Procedure for Defective Crankshaft Main Bearing Shells" .

Section 15.14.18
Troubleshooting Procedure for Defective Crankshaft Main Bearing Shells

To determine if defective crankshaft main bearing shells are causing low oil pressure, check main bearing to crankshaft journal clearances.‪

1. If main bearing shell-to-journal clearance is within 0.051-0.127 mm (0.002-0.005 in.), check for defective oil pump assembly; refer to "15.14.20 Troubleshooting Procedure for Defective Oil Pump Assembly" .
2. If main bearing shell-to-journal clearance is not within 0.051-0.127 mm (0.002-0.005 in.), refer to "15.14.19 Crankshaft Main Bearing Shell Repair" .

Section 15.14.19
Crankshaft Main Bearing Shell Repair

Perform the following steps to repair crankshaft main bearing shells:‪

1. Remove and replace defective crankshaft main bearing shells.
2. Verify crankshaft main bearing shells repair; refer to "15.14.19.1 Test Engine with New Crankshaft Main Bearing Shells" .

Section 15.14.19.1
Test Engine with New Crankshaft Main Bearing Shells

Perform the following steps to determine if new crankshaft main bearing shells have resolved low oil pressure:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run engine at rated speed.
2. Visually examine the oil pressure reading.
   1. If the oil pressure at rated speed is 241 kPa (35 psi) or more, no further troubleshooting is required. Shut down the engine.
   2. If the oil pressure at rated speed is less than 241 kPa (35 psi), shut down the engine. Check the oil pump assembly; refer to "15.14.20 Troubleshooting Procedure for Defective Oil Pump Assembly" .

Section 15.14.20
Troubleshooting Procedure for Defective Oil Pump Assembly

To determine if a defective oil pump is causing low oil pressure, perform the following steps:‪

1. Remove the oil pump assembly; refer to "3.3.1 Oil Pump Removal" .
2. Manually rotate the oil pump drive gear.
   1. If the drive gear rotates freely in the pump housing, call Detroit Diesel Customer Support Center at 313-592-5800.
   2. If the drive gear does not rotate freely, replace the oil pump assembly and verify repair; refer to "15.14.20.1 Test Engine with Replaced Oil Pump Assembly" .

Section 15.14.20.1
Test Engine with Replaced Oil Pump Assembly

Perform the following steps to determine if oil pump replacement resolved low oil pressure:‪

PERSONAL INJURY ‪
To avoid injury before starting and running the engine, ensure the vehicle is parked on a level surface, parking brake is set, and the wheels are blocked. ‪

1. Start and run the engine speed at rated speed.
2. Visually examine the oil pressure reading.
   1. If the oil pressure at rated speed is 241 kPa (35 psi) or more, no further troubleshooting is required. Shut down the engine.
   2. If the oil pressure at rated speed is less than 241 kPa (35 psi), shut down the engine and call Detroit Diesel Customer Support Center at 313-592-5800.