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List Of Parts To Inspect & Clean For Oil Pumps In Detroit Diesel 71 Series Inline Engines (271, 371, 471, 671)
A thorough inspection and cleaning of each oil pump component is essential to detect wear or damage that could lead to compromised oil flow and pressure, potentially causing severe engine issues. The following steps cover the inspection criteria and cleaning procedures for each vital part of the oil pump. Taking the time to inspect and clean these components will extend the longevity and efficiency of the oil pump and, in turn, the overall engine.
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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
1. Gears (Drive and Driven Gears)
The gears within the oil pump, specifically the drive and driven gears, are responsible for creating the necessary pressure to circulate oil throughout the engine. Any wear on these gears can lead to a reduction in oil flow efficiency, so careful inspection is crucial.
- Inspection Criteria:
- Scoring: Examine each tooth on both gears for scoring, which appears as fine lines or grooves on the gear surface. Scoring can indicate abrasive particles in the oil or worn surfaces within the pump.
- Worn Teeth: Look for rounded or uneven wear on the gear teeth. Worn teeth can lead to slippage, reduced oil pressure, and less effective oil distribution.
- Cracks or Fractures: Inspect each gear for cracks, especially around the root of each tooth. Cracked gears must be replaced immediately, as they are at risk of breaking under operational stress.
- Replacement: Any gear with visible signs of wear, scoring, or cracking should be replaced to avoid compromising the oil pump’s efficiency and preventing uneven wear on the bushings and other internal components.
2. Oil Pump Housing
The housing is the main structure that holds the pump’s internal components. It provides the channels through which oil flows, and any wear, damage, or obstruction within the housing can disrupt oil flow or lead to leaks.
- Inspection Criteria:
- Cracks: Check the housing, particularly around mounting points and internal oil channels, for any cracks. Cracked housing can lead to oil leaks, and such housings should be replaced.
- Internal Scoring or Wear: Look for wear or scoring inside the housing where the gears rotate. Scoring can create uneven surfaces that reduce clearance, leading to binding or increased friction.
- Obstructions in Flow Paths: For models with the scavenging pump, inspect both the primary and secondary (scavenging) sections for obstructions. Blockages or debris in the oil flow paths can impede circulation, especially in marine applications.
- Action: If scoring is light, polishing may suffice to restore a smooth surface. However, if cracks or deep grooves are present, the housing should be replaced, as attempts to repair may compromise structural integrity.
3. Relief Valve and Spring Assembly
The relief valve plays a crucial role in regulating oil pressure within the pump by bypassing excess oil when the pressure exceeds safe limits. This assembly consists of a plunger and a spring, which must operate reliably to maintain stable oil pressure.
- Inspection Criteria:
- Spring Tension: The spring in the relief valve is calibrated to open the valve at a specific pressure, typically around 105 psi (724 kPa). Inspect the spring for signs of weakening, corrosion, or damage. A weakened spring will reduce the valve’s ability to regulate pressure, potentially causing oil starvation at high speeds.
- Plunger Movement: The plunger should move freely within the valve body. Test its movement by pressing it down and releasing it to ensure there is no sticking or resistance. Dirt or corrosion can cause the plunger to stick, leading to inconsistent pressure regulation.
- Replacement: Replace any springs showing loss of tension or visible damage. If the plunger has visible wear or doesn’t move smoothly, clean it thoroughly or replace it if necessary.
4. Bushings
Bushings support the drive and driven gears, providing a low-friction interface for smooth gear rotation. In models with a scavenging pump, bushings are also present in the scavenging section, which should be inspected as well.
- Inspection Criteria:
- Scoring and Wear: Examine the inner surface of each bushing for scoring, which can occur if abrasive particles pass through the oil pump. Worn bushings can result in misaligned gears, reducing efficiency and causing additional wear on the gears.
- Clearance: Measure the clearance between the bushings and gears to ensure it falls within the specified tolerance for the Series 71 engine (typically 0.005 to 0.012 inches). Excessive clearance indicates bushing wear, leading to potential misalignment and loss of pressure.
- Replacement and Installation:
- Replace bushings that show significant wear, scoring, or excessive clearance.
- When installing new bushings, align them carefully and ream them to the manufacturer’s specifications. This alignment ensures that gears rotate smoothly without binding.
5. Screens and Additional Components (for Scavenging Models)
For models with a scavenging pump, screens and additional gears are included to support the scavenging function. These components ensure consistent oil pickup even when the engine is operated at an incline, such as in marine applications.
- Inspection Criteria:
- Screens: Check the inlet screens for clogs, wear, or damage. Screens should be free from debris to prevent contaminants from reaching the gears.
- Scavenging Gears: Inspect these gears just as you would the main drive and driven gears. Look for any signs of wear or scoring, as these gears play a role in managing oil circulation under inclined operation.
- Cleaning and Replacement:
- Clean screens thoroughly, as any debris can impact the scavenging function. Replace screens that show damage or are difficult to clean.
- Replace scavenging gears showing visible wear or damage, as they must work seamlessly with the primary gears to maintain efficient oil circulation.
Cleaning Process for Oil Pump Parts
After completing the inspection, it’s essential to clean each component thoroughly to remove any debris or oil residue that could interfere with reassembly or subsequent operation. Proper cleaning will help prevent contaminants from re-entering the lubrication system.
- Select a Suitable Solvent: Use a solvent specifically designed for automotive or heavy-duty engine parts to dissolve oil, grease, and other contaminants. Avoid using excessively harsh chemicals that could damage the metal surfaces or rubber seals.
- Immerse Components in the Solvent: Place each component—gears, housing, relief valve parts, bushings, and screens—in a solvent bath. Allow them to soak briefly to loosen any oil residue, grime, or metal particles. Use a brush to gently scrub components where necessary.
- Use Compressed Air for Drying: After soaking and scrubbing, dry each component using compressed air. Keep air pressure below 40 psi to avoid damaging small parts or blowing away delicate components. Ensure that all oil passages, gear teeth, and bushing surfaces are thoroughly dried and free from residual solvent.
- Final Inspection After Cleaning: Once the parts are dry, perform a final inspection to ensure that no residual dirt or grime remains. Re-check clearances and tolerances if any parts were reamed or otherwise modified during cleaning.
By meticulously inspecting and cleaning each part, you can ensure the oil pump is fully prepared for reassembly. This attention to detail in the inspection and cleaning process helps maintain efficient oil flow, proper pressure regulation, and overall engine health in the Detroit Diesel Series 71 engine.
