Oil Pump For Detroit Diesel 71 Series Inline Engines : Ensuring Proper Lubrication Throughout the Engine

October 25, 2024

Oil Pump For Detroit Diesel 71 Series Inline Engines (271, 371, 471, 671) : Ensuring Proper Lubrication Throughout The Engine

Right Hand Oil Pump - Used In Detroit Diesel 371, 471, and 671 Engines — Right Hand Oil Pump – Used In Detroit Diesel 371, 471, and 671 Engines

The oil pump in the Detroit Diesel Series 71 engine plays a crucial role in ensuring that all moving components of the engine are properly lubricated. By circulating oil under pressure, the oil pump minimizes friction between moving parts, helps maintain engine temperature, and ensures that the engine runs smoothly and efficiently. Proper maintenance of the oil pump is essential for preventing engine wear, overheating, or catastrophic failure due to insufficient lubrication.

Key Functions of the Oil Pump:

Circulating Engine Oil:
- The oil pump circulates oil through the engine, ensuring that critical components such as the crankshaft, camshaft, pistons, and valve train are continuously lubricated. Proper lubrication reduces friction and wear between these moving parts.
Maintaining Oil Pressure:
- The oil pump generates the necessary pressure to force oil through the engine’s oil galleries and into bearings, journals, and other components. Consistent oil pressure is vital to ensuring that all parts receive the correct amount of oil.
Heat Dissipation:
- By circulating oil through the engine, the oil pump also aids in dissipating heat generated by the friction of moving parts. Oil absorbs some of this heat and carries it to the oil cooler, where it is released, helping to maintain optimal operating temperatures.
Filtering Contaminants:
- The oil pump works in conjunction with the oil filter to remove contaminants from the oil, ensuring that dirt, debris, and metal particles do not damage engine components.

Components of the Oil Pump:

Pump Gears:
- The oil pump uses interlocking gears to create pressure and move oil through the system. These gears must be in good condition to maintain adequate oil pressure. Worn gears can result in insufficient oil flow and pressure loss.
Pump Housing:
- The pump housing encloses the gears and provides the pathway for oil flow. The housing must remain free of cracks or damage to prevent oil leakage and maintain internal pressure.
Relief Valve:
- The oil pump is equipped with a relief valve that prevents excessive oil pressure from damaging the engine. If the pressure exceeds a certain threshold, the relief valve opens to allow excess oil to bypass the system.
Oil Pickup Tube:
- The pickup tube extends into the engine’s oil sump to draw oil from the sump into the pump. It must remain free from blockages to ensure consistent oil flow into the pump.

Critical Tolerances and Measurements for the Oil Pump:

Oil Pump Gear Clearance:
- The clearance between the oil pump gears and the pump housing is critical to maintaining proper oil pressure. Excessive clearance can lead to reduced oil pressure, while too little clearance can cause binding or damage to the gears. For the Detroit Diesel Series 71 engine, the gear-to-housing clearance typically falls within 0.002 to 0.004 inches (0.05 to 0.10 mm).
- Measurement Process: Use a feeler gauge to measure the clearance between the oil pump gears and the housing. If the clearance exceeds the specified limits, the pump gears or housing may need to be replaced or resurfaced.
Pump Gear End Play:
- The end play of the oil pump gears is the axial movement of the gears within the pump housing. Excessive end play can reduce pump efficiency and cause wear on the gears and housing. The end play should generally be between 0.001 to 0.003 inches (0.025 to 0.076 mm).
- Measurement Process: Use a dial indicator to measure the axial movement of the gears. If the end play exceeds the manufacturer’s specifications, shims or spacers may be required to restore proper clearances.
Oil Pressure Specifications:
- The oil pressure produced by the pump must be sufficient to lubricate all engine components. For the Detroit Diesel Series 71 engine, typical oil pressure ranges from 30 to 45 psi (207 to 310 kPa) at operating temperature and under normal load.
- Measurement Process: Use an oil pressure gauge to measure the oil pressure at various engine speeds. If the pressure is too low, inspect the oil pump for wear or blockages, and check the oil pickup tube for clogs. If the pressure is too high, inspect the relief valve for proper function.
Relief Valve Opening Pressure:
- The relief valve must open at the correct pressure to prevent excessive oil pressure from damaging engine components. The relief valve in the oil pump typically opens at around 50 to 60 psi (345 to 414 kPa).
- Measurement Process: Test the relief valve using a hydraulic or pressure testing tool. If the valve does not open at the specified pressure, it may need to be replaced.

Oil Pump Inspection and Maintenance:

Visual Inspection for Wear and Damage:
- Regularly inspect the oil pump gears, housing, and relief valve for signs of wear, scoring, or damage. Worn pump gears or a cracked housing can result in oil pressure loss and insufficient lubrication. Any damaged components should be replaced to prevent engine failure.
Checking Oil Pressure:
- Use an oil pressure gauge to regularly monitor the engine’s oil pressure. Sudden drops in oil pressure may indicate pump wear, a blocked pickup tube, or a faulty relief valve. Address any pressure irregularities immediately to avoid severe engine damage.
Relief Valve Function Testing:
- The relief valve is critical for preventing excessive oil pressure. Test the relief valve periodically to ensure that it opens at the correct pressure. If the valve sticks or opens too early, it may need to be replaced to ensure proper oil pressure regulation.
Checking the Oil Pickup Tube:
- Ensure that the oil pickup tube is free from blockages or sludge buildup, which could restrict oil flow to the pump. A blocked pickup tube can starve the engine of oil, causing excessive wear and overheating. Clean the pickup tube as part of routine maintenance.
Oil Pump Gear Wear:
- Use a micrometer to measure the wear on the pump gears. Excessive wear can lead to poor oil circulation and reduced pressure. Replace the gears if they have worn beyond the manufacturer’s specifications.

Oil Pump Removal and Installation:

Removing the Oil Pump:
- To remove the oil pump, drain the engine oil and remove the oil pan. Disconnect the oil pickup tube and remove the pump retaining bolts. Carefully extract the oil pump from the engine, taking care not to damage the gears or housing.
- Inspection After Removal: Once the pump is removed, inspect the gears, housing, and pickup tube for signs of wear or damage. Clean all components thoroughly before reinstallation.
Installing the Oil Pump:
- Before reinstalling the oil pump, ensure that all components are clean and properly lubricated. Align the pump with the oil pickup tube and secure it with the retaining bolts. Torque the bolts to the manufacturer’s specifications, typically around 25 to 30 lb-ft (34 to 41 Nm).
Priming the Oil Pump:
- After installing the oil pump, it’s important to prime the pump to ensure proper oil flow during engine startup. Manually prime the oil pump by filling it with oil or using an external priming tool. This step helps prevent dry starts and ensures that the pump delivers oil immediately when the engine starts.
Testing Oil Pressure After Installation:
- Once the pump is installed and primed, start the engine and monitor the oil pressure with a pressure gauge. Ensure that the oil pressure reaches the specified range (30 to 45 psi) and remains stable during operation.

Common Symptoms of Oil Pump Problems:

Low Oil Pressure: A drop in oil pressure may indicate wear in the oil pump gears, a blocked pickup tube, or a malfunctioning relief valve. Low oil pressure can lead to insufficient lubrication, resulting in excessive engine wear or damage.
Overheating: If the oil pump is not circulating oil properly, the engine may overheat due to insufficient lubrication and heat dissipation. This can cause components such as the pistons, crankshaft, and bearings to fail.
Oil Leaks: Leaks around the oil pump or oil pickup tube can result in a loss of oil pressure and reduced lubrication. Inspect the oil pump housing, seals, and gaskets for signs of oil leakage.
Unusual Engine Noise: If the oil pump is failing or the engine is not receiving sufficient oil, you may hear knocking or tapping noises from the engine as metal parts wear against each other without proper lubrication.

Conclusion Of The Oil Pump Section

The oil pump is essential for maintaining proper lubrication and preventing engine damage in the Detroit Diesel Series 71 engine. Regular inspection and maintenance, including monitoring oil pressure, testing the relief valve, and ensuring proper gear and housing clearances, are critical for ensuring that the oil pump functions effectively. By following these maintenance practices and replacing worn components, operators can ensure that their engine remains properly lubricated, preventing premature wear and costly repairs.

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Oil Pump For Detroit Diesel 71 Series Inline Engines : Ensuring Proper Lubrication Throughout the Engine