Steps To Disassemble A 71 Series Inline Detroit Diesel Engine Oil Pump (271, 371, 471, 671)

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Disassembling the oil pump is a crucial step in performing thorough maintenance on the Detroit Diesel Series 71 engine. Proper disassembly ensures that each component can be cleaned, inspected, and replaced if necessary. This process is especially important in models that include a scavenging pump for marine or inclined operations, as additional parts and considerations apply. Below is a detailed, step-by-step procedure to safely disassemble the oil pump, ensuring that all parts are handled with care to prevent damage.

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Oil Pump For Detroit Diesel 271

Oil Pump For Detroit Diesel 371 – Non Turbo 2-Valve

Oil Pump For Detroit Diesel 371 – Non Turbo 4-Valve

Oil Pump For Detroit Diesel 471 – Non Turbo 2-Valve

Oil Pump For Detroit Diesel 471 – Non Turbo 4-Valve

Oil Pump For Detroit Diesel 671 – Non Turbo 2-Valve

Oil Pump For Detroit Diesel 671 – Non Turbo 4-Valve

Oil Pump For Detroit Diesel 671 – Turbo

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1. Preparation and Initial Steps

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• Drain the Engine Oil: Begin by draining the engine oil to avoid spills and contamination during the disassembly process. Ensure the engine has cooled down sufficiently to avoid burns.
• Gather Tools and Equipment: Make sure to have all necessary tools on hand, including a wrench set, torque wrench, feeler gauge, puller tools, solvent for cleaning, and a suitable container for parts and small components.
• Work Area Setup: Set up a clean, organized workspace. Label containers for small parts and fasteners to keep track of each component, as this will make reassembly easier and prevent the loss of small parts.
  

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2. Remove the Oil Pan

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The oil pan needs to be removed to access the oil pump assembly located on the main bearing caps:

• Unbolt the Oil Pan: Using a wrench, carefully remove the bolts that secure the oil pan to the engine block. Work in a cross-pattern to evenly release the pressure.
• Separate the Oil Pan: Gently tap the oil pan with a rubber mallet if it’s stuck due to the gasket seal. Avoid prying, which can damage the mating surfaces. Once detached, set the oil pan aside and inspect it for any sludge or metal shavings, as these could indicate wear in the engine.
  

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3. Detach the Oil Pump Assembly

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• Locate the Oil Pump Mounting Bolts: The oil pump is typically mounted on the main bearing caps. Identify the bolts securing the pump to the caps, noting their locations as you’ll need to reinstall them in the correct spots during reassembly.
• Remove the Mounting Bolts: Carefully remove the bolts with a wrench. Some models may have shims located between the pump and the bearing caps. Take note of the shim placement, as they help achieve proper gear clearance and must be reinstalled in the exact same configuration.
• Lower the Oil Pump Assembly: With the bolts and shims removed, gently pull down the oil pump assembly. Be mindful of any seals or gaskets attached to the pump that could be damaged during removal.
  

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4. Separate the Drive and Driven Gears

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After the pump assembly is removed, you’ll need to disassemble the internal components:

• Access the Gear Housing: In most Series 71 models, the drive and driven gears are located within the main pump housing. Begin by removing any covers or securing bolts that shield the gears.
• Use a Gear Puller (if required): For some models, a gear puller may be necessary to detach the gears without damaging them or the housing. Carefully position the puller to avoid misalignment.
• Remove the Drive Gear: Start by removing the drive gear from the pump shaft. Take care to keep the gear teeth clean, as any contamination can interfere with the reassembly process.
• Remove the Driven Gear: Once the drive gear is removed, proceed to the driven gear, ensuring both gears are stored in a safe, clean area to prevent scratches or dirt buildup.
  

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5. Disassemble the Relief Valve Assembly

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The relief valve assembly regulates oil pressure and is typically located within the oil pump housing:

• Locate the Relief Valve: Identify the relief valve within the pump housing. It usually consists of a plunger and a spring assembly.
• Remove the Retaining Clip or Cover: Some models use a retaining clip, while others may have a threaded cover securing the relief valve in place. Use the appropriate tool (pliers or wrench) to carefully remove the clip or cover, keeping track of each part for reassembly.
• Extract the Spring and Plunger: Once the cover or clip is removed, gently pull out the spring and plunger. The spring should be carefully handled to avoid losing or damaging it. Set both parts aside for cleaning and inspection.
  

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6. Disassemble Additional Components in Marine or Inclined Models

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In marine and inclined models equipped with a scavenging pump, there are additional steps to take during disassembly:

• Scavenging Gear Set: Locate the scavenging gear set, typically in a secondary compartment of the pump housing. These gears help move oil from the front to the rear of the pan during angled operation.
• Remove Scavenging Gears: Carefully pull out the scavenging gears. If they’re tightly fitted, a small puller or extractor tool may be required to avoid damaging the teeth.
• Detach Spacer and Screens: The scavenging section often includes a spacer and inlet screens. Remove the spacer and screens carefully, taking note of their orientation, as they play a key role in filtering oil and maintaining flow in angled conditions.
  

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7. Inspect and Organize Components

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With all parts removed, it’s essential to inspect each component before cleaning:

• Check Gear Teeth: Look for signs of wear or chipping on the gear teeth, as damaged gears can reduce pump efficiency. If wear is noticeable, consider replacing the affected gears.
• Inspect the Bushings: Bushings that support the gears should be checked for scoring or uneven wear, as these can lead to misalignment and increased friction. Replace any bushings that show significant wear.
• Examine the Relief Valve Spring and Plunger: Check the spring for any signs of weakening or deformation. The plunger should move smoothly within the valve body without sticking.
• Clean All Components: After inspection, immerse all parts in a suitable solvent to remove sludge, debris, and oil residue. Allow them to dry completely, using compressed air if necessary, but keep air pressure below 40 psi to avoid damaging small parts.
  

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8. Document Any Model-Specific Adjustments

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For Series 71 engines with model-specific features, such as the scavenging pump in marine models, make detailed notes on the placement and orientation of each additional component. Photographing each step can aid reassembly, particularly if shims, spacers, or additional screens are involved.

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Reassembly Preparation

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Before proceeding with reassembly, ensure that all parts are clean, dry, and free from defects. Organize parts according to their order of reinstallation and double-check that each component matches its intended orientation. This careful preparation will help streamline the reassembly process and reduce the risk of errors.

This thorough disassembly process ensures that each component of the Series 71 oil pump is ready for inspection, cleaning, and possible replacement. Following these steps helps maintain the integrity of the oil pump and ensures it will function correctly upon reinstallation, supporting optimal engine lubrication and performance.

 

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