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Crankshaft — Inspection & Measurement
Procedure 001-016 | Journals, Taper, Out-of-Round, Thrust Face
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Crankshaft Journal Specifications — Manual 3666206
Con Rod Journal — STD MIN
2.991in
75.96 mm
Con Rod Journal — Out-of-Round MAX
0.0020in
0.050 mm
Con Rod Journal — Taper MAX
0.0005in
0.013 mm
Main Journal — STD MIN
3.857in
97.96 mm
Main Journal — Out-of-Round MAX
0.002in
0.05 mm
Main Journal — Taper MAX
0.001in
0.01 mm
Thrust Face Width — MIN
1.692in
42.98 mm
Thrust Face Width — MAX
1.696in
43.08 mm
Rear Seal Flange OD — MIN
5.117in
129.98 mm
Rear Seal Flange OD — MAX
5.119in
130.03 mm
Oil Seal Wear Groove MAX
0.010in
0.25 mm
Max Con Rod Bearing Clearance
0.0046in
0.117 mm
Undersize AvailabilityCon rod journals: 0.010", 0.020", 0.030", 0.040" undersize. Main journals: 0.010", 0.020" undersize. Crankshafts machined undersize are marked on the front counterweight.
Crankshaft Measurement Procedure
WarningCrankshaft weighs more than 23 kg [50 lb]. Use nylon lift sling Part No. 3375957 around journals #3 and #4 and attach to a hoist.
- Use fine crocus cloth to polish all machined journal surfaces. Use a bristle brush to clean all oil drillings.
- Steam-clean the crankshaft and dry with compressed air. Blow out all threaded holes and oil drillings.
- Inspect all threaded capscrew holes for damage. Repair with thread chaser or threaded insert kit Part No. 3822709. If more than two holes damaged on one end, replace crankshaft.
- Measure front and rear oil seal contact areas for wear groove. MAX: 0.25 mm [0.010 in]. Front and rear wear sleeves are available if worn beyond limit.
- Inspect all connecting rod and main journals for deep scoring or overheating discoloration.
- Using a micrometer, measure each connecting rod journal diameter. Record in measurement table below. MIN: 2.991 in [75.96 mm].
- Measure connecting rod journal out-of-roundness and taper at each journal. Record all values.
- Measure each main bearing journal diameter. Record in measurement table below. MIN: 3.857 in [97.96 mm].
- Measure main journal out-of-roundness and taper. Record all values.
- Measure thrust face width at journal #4. Record value.
- Measure rear oil seal flange outside diameter. Record value.
- Apply light preservative oil to crankshaft if not installing immediately. Cover with plastic to prevent contamination.
Required Tools & Part Numbers
Nylon Lift Sling
3375957
Threaded Insert Kit
3822709
Engine Barring Tool
3377371
Scotch-Brite 7448
3823258
Dial Bore Gauge
0.0001" resolution
For bearing clearance — Secs 2 & 3
Outside Micrometer
3"–4" range
Journal OD measurement
Torque Angle Gauge
—
For 60° / 90° angle torque steps
Cummins NoteReference C Series Shop Manual, Bulletin 3666008 for full crankshaft regrind specifications. Cummins recommends regrinding ALL main or ALL connecting rod journals when any one requires regrinding.
Crankshaft Measurements
| Measurement | Factory Spec | Location | Actual Value | Status | Notes | Photo |
|---|
Visual Inspection
Technician Notes — Crankshaft
2
Main Bearings — Inspection & Torque Sequence
Procedure 001-006 | 7 Main Bearings, Thrust Bearing, End Play
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Main Bearing Specifications — Manual 3666206
Bearing Shell Thickness — MIN
0.1357in
3.446 mm
Bearing Shell Thickness — MAX
0.1360in
3.454 mm
Thrust Bearing Flange — MIN
0.139in
3.52 mm
Thrust Bearing Flange — MAX
0.141in
3.57 mm
Crankshaft End Play — MIN
0.005in
0.127 mm
Crankshaft End Play — MAX (New)
0.013in
0.330 mm
End Play MAX (Used) — Replace
0.021in
0.533 mm — replace crank
Max Main Bearing Clearance
0.005in
0.13 mm · Bore ID w/ shell − journal OD
Dial Bore Gauge MethodTorque bearing caps to Step 1 (37 ft-lb) only. Measure bore ID with shells installed using a dial bore gauge. Subtract the crankshaft journal OD (from Section 1) to get oil clearance. Maximum clearance is 0.005". Do NOT rotate crankshaft with gauge installed.
Important — Bearing IdentificationUpper bearings have two oil holes; lower bearings have NO holes. Number 4 journal uses a flanged upper bearing (thrust bearing). All caps are numbered — Number 1 starts at the front, numbers face the CAMSHAFT side of the engine.
NG Engine NoteUse only Cummins-approved lubricating oil for natural gas engines. Improper oil is the primary cause of reduced main bearing life.
Main Bearing Cap Torque Sequence — 3-Step Method
Tighten all caps evenly following illustrated sequence (front to rear, alternating)
Step 1 — Initial
37
ft-lb
50 N·m
→
Step 2 — Final
70
ft-lb
95 N·m
→
Step 3 — Angle
60°
clockwise turn
Angle torque
Critical CheckThe crankshaft MUST rotate freely after all main bearing caps are tightened to final torque. If it does not rotate freely, loosen all caps and inspect bearing sizes and installation.
End Play ProcedureAfter torquing, install dial indicator on oil pan flange. Push crankshaft toward rear, zero indicator, then push toward front. Record end play. If less than 0.127 mm [0.005 in], loosen caps, push crank fore and aft, re-torque in sequence.
Main Bearing Installation Procedure
- Mark all bearing caps for location before removal. Caps are numbered — do NOT pry caps off. Use two cap bolts to "walk" caps off.
- Clean cap, block saddle, and bearing shells with solvent. Use Scotch-Brite 7448 on seating surfaces. Do NOT use wire brush on bearings.
- Inspect bearing shells for pitting, flaking, corrosion, lock tang damage, or deep scratches. Replace as a set if any damage found.
- Measure bearing shell thickness. MIN: 3.446 mm [0.1357 in]. Discard if below minimum.
- Install upper bearing shells (with oil holes) into block saddles. Install lower shells (no holes) into caps.
- Install #4 flanged thrust bearing with oil hole facing up.
- Lubricate bearing shells with clean engine oil before installing crankshaft.
- Lower crankshaft carefully into block. Install all caps in numbered sequence — numbers face camshaft side.
- Tighten all caps in 3-step torque sequence (see Torque Sequence tab).
- Verify crankshaft rotates freely after all caps are torqued.
- Measure and record crankshaft end play with dial indicator.
- Dial Bore Gauge — Bearing Clearance: With caps torqued to Step 1 (37 ft-lb) only, measure bore ID with shells installed using a dial bore gauge. Record each bore ID. Subtract the corresponding journal OD (Section 1) to calculate oil clearance. Max clearance 0.005". Enter bore ID and clearance values in the measurement table below.
Main Bearing Measurements
| Measurement | Factory Spec | Location | Actual Value | Status | Notes | Photo |
|---|
Visual Inspection
Technician Notes — Main Bearings
3
Connecting Rod Bearings — Inspection & Torque
Procedure 001-005 | 6 Con Rod Bearings, Side Clearance
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Connecting Rod Bearing Specifications — Manual 3666206
New Bearing Shell Thickness
Record as-built
New bearings installed every overhaul — record actual thickness for reference
Con Rod Side Clearance — MIN
0.004in
0.10 mm
Con Rod Side Clearance — MAX
0.013in
0.33 mm
Max Con Rod Bearing Clearance
0.0046in
0.117 mm · Bore ID w/ shell − journal OD
Dial Bore Gauge MethodTorque rod caps to Step 1 (22 ft-lb) only. Measure rod bore ID with shells installed using a dial bore gauge. Subtract the con rod journal OD (from Section 1) to get oil clearance. Maximum clearance is 0.0046". Do NOT rotate crankshaft with gauge installed.
Cap OrientationThe locking tang of the connecting rod cap MUST be toward the CAMSHAFT SIDE of the cylinder block. The crankshaft must rotate freely after each cap is installed.
Connecting Rod Torque Values
Engines with Connecting Rod NUTS
Step 1
22
ft-lb
30 N·m
→
Step 2
52
ft-lb
70 N·m
→
Step 3 — Angle
60°
turn
Angle torque
Engines with Connecting Rod CAPSCREWS
Step 1
22
ft-lb
30 N·m
→
Step 2
52
ft-lb
70 N·m
→
Step 3 — Angle
90°
turn
Angle torque
Critical CheckThe locking tang of the connecting rod cap MUST be toward the CAMSHAFT SIDE of the cylinder block. The crankshaft must rotate freely after each cap is installed.
Con Rod Bearing Installation Procedure
- Before removal, mark each bearing shell with L (lower) or U (upper) and the journal number. Verify serial numbers on rod and cap match.
- Clean cap, capscrews, and bearings with solvent and soft bristle brush. Use Scotch-Brite 7448 on seating surfaces. Do NOT use wire brush on bearings.
- Inspect bearing shells for pitting, flaking, corrosion, lock tang damage, or deep scratches. Replace as a set if any damage found.
- Install NEW bearing shells (std or undersize to match journal). Record the new bearing thickness for reference.
- Lubricate bearing shells with clean engine oil before installation.
- Install bearing shells. Ensure locking tang seats in notch of rod and cap.
- Install rod cap — ensure cap number matches rod number and cap faces camshaft side.
- Tighten nuts/capscrews alternating in 3-step torque sequence (see Torque Values tab).
- Verify crankshaft rotates freely after each cap installation.
- Measure and record con rod side clearance with feeler gauge.
- Dial Bore Gauge — Bearing Clearance: With rod caps torqued to Step 1 (22 ft-lb) only, measure rod bore ID with shells installed using a dial bore gauge. Record each bore ID. Subtract the corresponding con rod journal OD (Section 1) to calculate oil clearance. Max clearance 0.0046". Enter bore ID and clearance values in the measurement table below.
Connecting Rod Measurements
| Measurement | Factory Spec | Location | Actual Value | Status | Notes | Photo |
|---|
Visual Inspection
Technician Notes — Connecting Rod Bearings
4
Cylinder Liner, Pistons & Rings
Procedures 001-028, 001-054, 001-055 | Bore, Piston Clearance, Liner Protrusion
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Cylinder Liner & Piston Specifications — Manual 3666206
Liner Bore Diameter — MAX
4.490in
114.04 mm
Liner Out-of-Round — MAX
0.002in
0.04 mm
Liner Taper — MAX
0.002in
0.04 mm
Con Rod Side Clearance — MIN
0.004in
0.10 mm
Con Rod Side Clearance — MAX
0.013in
0.33 mm
Block Liner Bore — Press-Fit (Measure Before Liner Install)
Block Press-Fit Bore — MIN
5.154in
130.90 mm
Block Press-Fit Bore — MAX
5.156in
130.95 mm
Liner OD (Top Press-Fit) — MIN
5.1550in
130.938 mm · for reference
Liner OD (Top Press-Fit) — MAX
5.1558in
130.958 mm · for reference
Block Bore MeasurementMeasure the bare block press-fit bore before installing new liners. Use a dial bore gauge. Liner OD is intentionally larger than block bore — this interference is the press fit. If block bore exceeds 5.156", the bore is worn and liner will not seat correctly.
Liner InspectionInspect liner bore for vertical scratches deep enough to catch a fingernail — replace if found. Heavy polish (no hone marks visible) requires liner replacement. Do NOT hone or deglaze liners — this destroys the crosshatch pattern needed for oil control.
NG Engine — Piston SpecificationVerify correct piston part number for natural gas application. NG engines use a lower compression ratio piston (8.5:1 CR) compared to diesel variant. Installing wrong pistons will cause detonation damage.
Cylinder Liner Protrusion — Manual 3666206
New Block + New Liners — MIN
0.001in
0.025 mm
New Block + New Liners — MAX
0.005in
0.122 mm
Used Block + Used Liners — MIN
0.000in
0.000 mm
Used Block + Used Liners — MAX
0.005in
0.122 mm
New Block + Used Liners — MIN
0.001in
0.025 mm
New Block + Used Liners — MAX
0.005in
0.122 mm
Used Block + New Liners — MIN
0.000in
0.000 mm
Used Block + New Liners — MAX
0.005in
0.122 mm · Your scenario
MAX Difference Adjacent Cylinders
0.002in
0.051 mm
Liner Clamp TorqueWhen clamping liners for protrusion measurement: Torque Value: 68 N·m [50 ft-lb]. Use liner protrusion gauge Part No. 3823495. Measure at 4 points 90° apart. Remove clamps after measurement.
Piston & Ring Installation Procedure
- Measure each cylinder liner bore at 4 positions 90° apart at top and bottom of piston travel. Record all values.
- Inspect liner bore for scoring, scuffing, or vertical scratches. Inspect for heavy polish (no hone marks). Replace liners that fail inspection.
- Measure liner protrusion at 4 points 90° apart. Clamp liner at 68 N·m [50 ft-lb] for measurement. Record all values.
- Verify correct piston part number for NG application (8.5:1 compression ratio).
- Install oil control ring first, then intermediate ring, then top ring (chrome finish). Stagger ring gaps 120° apart during installation — do NOT align gaps.
- Lubricate cylinder bore and piston rings with clean engine oil.
- Use piston ring compressor to install piston. Ensure connecting rod locking tang faces camshaft side.
- Install rod cap — verify serial numbers match. Torque rod nuts/capscrews in 3-step sequence.
- Measure and record connecting rod side clearance. Verify crankshaft rotates freely.
| Measurement | Factory Spec | Location | Actual Value | Status | Notes | Photo |
|---|
Visual Inspection
Technician Notes — Cylinder Liner, Pistons & Rings
5
Cylinder Head — Inspection & Measurement
Procedure 002-004 | Flatness, Valve Seat Recession, Pressure Test | Head rebuilt externally
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Cylinder Head Specifications — Manual 3666206
Note — Externally Rebuilt HeadCylinder head is rebuilt at an external machine shop. Valve guide replacement and valve seat machining are performed by the shop. Verify the following specifications upon return.
Combustion Face Flatness MAX
0.006in
0.15 mm per full length
MAX Material Removal
0.040in
1.0 mm from combustion face
Valve Stem OD (Intake & Exhaust)
0.373–0.374in
9.48–9.50 mm
Valve Seat Recession — Intake MAX
0.163in
4.14 mm (min 0.145")
Valve Seat Recession — Exhaust MAX
0.143in
3.63 mm (min 0.125")
Intake Valve Head Dia MAX
2.123in
53.93 mm
Exhaust Valve Head Dia MAX
1.852in
47.03 mm
Pressure Test
30psi
Hold 3 min — no leaks
Valve Spring Free Length MIN
2.16in
Intake: 54.9 mm
NG Engine — Valve Seat CriticalNatural gas engines require hardened valve seat inserts. Valve seat recession is the primary wear indicator on NG engines. Measure recession on ALL 12 valves. Seats must be replaced if recession exceeds specification.
Cylinder Head Inspection Procedure
- Receive rebuilt head from machine shop. Verify shop documentation — confirm valve guide replacement, seat machining, and pressure test were performed.
- Remove all carbon deposits from combustion chambers and valve faces using abrasive hand pad Part No. 3823258 and solvent.
- Inspect combustion deck for cracks, erosion, pitting, or hot spots. Pay special attention to areas between valves and around injector bores.
- Use a straight edge and feeler gauge to measure combustion face flatness. MAX: 0.15 mm [0.006 in] full length. MAX material removal: 1.0 mm [0.040 in].
- Inspect all coolant passages for scale, blockage, or corrosion. Clean as required.
- Pressure test cylinder head: block all ports, apply 207 kPa [30 psi] air pressure, submerge in water tank. Hold 3 minutes — no bubbles permitted.
- Measure valve seat recession on all 12 valves. Record each measurement. Replace seats if recession exceeds specification.
- Inspect valve faces for pitting, burning, or erosion. Inspect valve stems for scoring or bending.
- Verify hardened valve seat inserts are installed (NG specification). Standard seats are NOT acceptable for natural gas service.
Valve Seat Insert Part Numbers
Intake Seat — Standard
3914841
OD: 53.992–54.008 mm
Exhaust Seat — Standard
3914838
OD: 47.092–47.108 mm
Intake Seat — 0.010" OS
3914839
OD: 54.246–54.262 mm
Exhaust Seat — 0.010" OS
3914836
OD: 47.346–47.362 mm
Intake Seat — 0.020" OS
3914840
OD: 54.500–54.516 mm
Exhaust Seat — 0.020" OS
3914837
OD: 47.600–47.616 mm
Valve Guide Installation ToolsIntake Guide Tool: Part No. 3823269 | Exhaust Guide Tool: Part No. 3823270 | Valve Spring Compressor: Part No. 3163292 | Boot Plier (stem seals): Part No. 3163293
| Measurement | Factory Spec | Location | Actual Value | Status | Notes | Photo |
|---|
Visual Inspection
Technician Notes — Cylinder Head
6
Head Bolt Torque Sequence — 26 Capscrews
Procedure 002-004 | 5-Step Torque + Angle Method | 14 Long + 12 Short
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5-Step Torque Sequence — Reused Cylinder Block or Reused Capscrews
Fig. kn9csob — Cylinder Head Capscrew Torque Sequence (Manual 3666206) | ← Front of Engine
Follow illustrated sequence above for all steps
Step 1 — All 26
52
ft-lb
70 N·m
→
Step 2 — 14 Long Only
107
ft-lb
145 N·m
→
Step 3 — 12 Short Only
52
ft-lb
70 N·m (relaxation)
→
Step 4 — 14 Long Only
107
ft-lb
145 N·m
→
Step 5 — All 26
90°
angle turn
Use angle gauge
Long Bolt Positions (14 bolts)Positions: 1, 2, 7, 8, 9, 10, 15, 16, 17, 18, 23, 24, 25, 26 (two center rows)
Short Bolt Positions (12 bolts)Positions: 3, 4, 5, 6, 11, 12, 13, 14, 19, 20, 21, 22 (outer rows — exhaust and intake sides)
Torque Sequence — New Cylinder Block or New Capscrews
Fig. kn9csob — Follow this sequence for all steps | ← Front of Engine
New Block/New Bolts — Different Torque Values Apply
Step 1 — All 26
59
ft-lb
80 N·m
→
Step 2 — All 26
70
ft-lb
95 N·m
→
Step 3 — 14 Long
107
ft-lb
145 N·m
→
Step 4 — 6 Short Exhaust
77
ft-lb
105 N·m
→
Step 5 — 6 Short Intake
70
ft-lb
95 N·m
Important Notes & Cautions
Angle Torque MethodThe top of each cylinder head capscrew is marked with a dot and a window. Orient the dot, mark the cylinder head adjacent to the dot, then rotate until the mark falls into the window. Use torque angle gauge Part No. 3823878 (1/2" drive) or 3823879 (3/4" drive).
Short Bolt Relaxation — Step 3The short capscrews must be re-torqued to 70 N·m [52 ft-lb] in Step 3 due to cylinder head relaxation. This is required to obtain proper cylinder head sealing pressure.
Torque Sequence DirectionAlways follow the illustrated center-out sequence. Start from the center of the head and work outward. This ensures even gasket compression and prevents head warpage.
Click each bolt to mark as torqued — Gold = Long bolt | Gray = Short bolt
Technician Notes — Head Bolt Torque
7
Valvetrain — Valve Lash & Rocker Lever
Procedure 003-004 & 003-008 | C8.3G: Intake 0.012" / Exhaust 0.024" — Set Cold
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Valve Lash & Valvetrain Specifications — C8.3G (Manual 3666206)
C8.3G Intake Valve Lash (Cold)
0.012in
0.305 mm — set cold below 60°C
C8.3G Exhaust Valve Lash (Cold)
0.024in
0.610 mm — set cold below 60°C
Locknut Torque
212in-lb
24 N·m
Camshaft End Clearance — MIN
0.005in
0.12 mm
Camshaft End Clearance — MAX
0.018in
0.46 mm
Gear Backlash — MIN
0.003in
0.08 mm
Gear Backlash — MAX
0.013in
0.33 mm
Camshaft Bushing Bore ID — MAX
2.367in
60.12 mm
Camshaft Thrust Plate — MIN
0.368in
9.34 mm
Camshaft Thrust Plate — MAX
0.377in
9.58 mm
NG Engine — Valve Lash CriticalNatural gas engines run hotter than diesel. Correct valve lash is critical for valve longevity. Always set lash cold (below 60°C / 140°F). Incorrect lash causes rapid valve seat recession.
C8.3G vs. L Gas PlusC8.3G and C Gas Plus: Intake 0.012" / Exhaust 0.024". L Gas Plus engines use different specs: Intake 0.014" / Exhaust 0.030". Confirm engine model before setting lash.
Valve Lash Adjustment Procedure — C8.3G (2-Position Method)
Engine Must Be ColdCheck and set valves with engine cold — below 60°C [140°F]. Remove valve cover before beginning.
- Remove valve cover. Refer to Procedure 003-011.
- Rotate engine until the exhaust valve on cylinder #6 begins to close and the intake begins to open. At this point the engine is at TDC on cylinder #1.
- STEP A: With engine at TDC #1, set the valves shown in the Step A diagram (see Step A Diagram tab). Intake clearance: 0.012" (0.305 mm). Exhaust clearance: 0.024" (0.610 mm).
- The clearance is correct when slight resistance is felt when the feeler gauge is slipped between the valve stem and the rocker lever.
- After adjusting each valve, hold the adjusting screw and tighten the locknut. Torque: 24 N·m [212 in-lb].
- After tightening the locknut, recheck the valve clearance to confirm the setting has not changed.
- Mark the vibration damper. Rotate the crankshaft 360 degrees.
- STEP B: Set the valves shown in the Step B diagram (see Step B Diagram tab). Use the same clearances: Intake 0.012", Exhaust 0.024".
- After tightening each locknut, recheck the clearance to confirm it has not changed.
- After setting all valves, rotate engine one full revolution and recheck lash on all 12 valves to confirm settings.
- Install new sealing O-rings on the capscrews. Install the rubber seal into the groove in the valve cover. Install valve cover. Torque: 24 N·m [212 in-lb].
Step A — Valves to Set at TDC Cylinder #1
Step AWith engine at TDC on cylinder #1 (both valves closed on #1), set the valves indicated below. I = Intake, E = Exhaust.
Step A — Set These Valves at TDC #1
Step A ValvesCylinder 1: Intake & Exhaust | Cylinder 2: Intake | Cylinder 4: Exhaust | Cylinder 5: Intake & Exhaust
Step B — Valves to Set After 360° Rotation
Step BAfter marking the damper and rotating the crankshaft 360 degrees, set the valves indicated below.
Step B — Set These Valves After 360° Rotation
Step B ValvesCylinder 2: Exhaust | Cylinder 3: Intake & Exhaust | Cylinder 4: Intake | Cylinder 6: Intake & Exhaust
| Measurement | Factory Spec | Location | Actual Value | Status | Notes | Photo |
|---|
Visual Inspection
Technician Notes — Valvetrain
8
Oil Pump — Inspection & Backlash
Procedure 007-019 | Gear Backlash, Gear-to-Housing Clearance, Visual Inspection
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Oil Pump Specifications — Manual 3666206, Proc. 007-019
Large Gear Backlash — MIN
0.003in
0.08 mm
Large Gear Backlash — MAX
0.013in
0.33 mm
Small Gear Backlash — MIN
0.011in
0.28 mm
Small Gear Backlash — MAX
0.019in
0.48 mm
Min Oil Pressure — Idle (Hot)
10psi
69 kPa · after overhaul verify
Min Oil Pressure — Rated Speed
40psi
276 kPa · after overhaul verify
Natural Gas EngineUse only Cummins-approved lubricating oil for natural gas engines. Improper oil accelerates pump wear and reduces bearing life. Verify oil specification before fill.
Backlash Measurement MethodMeasure gear backlash with a dial indicator on the gear tooth while holding the mating gear stationary. Rock the gear being measured and record total indicator movement. Measure at 3 points around the gear and record the highest reading.
Oil Pump Removal, Inspection & Installation — Proc. 007-019
- Drain engine oil completely. Remove oil pan (Proc. 007-025) and oil suction tube (Proc. 007-035).
- Remove oil pump mounting bolts. Note orientation before removal — pump must go back in the same position.
- Remove oil pump from the engine block. Do not pry against pump housing or block mating surfaces.
- Disassemble pump: Remove pump cover plate. Note orientation of all internal gears before removing — mark if needed. Remove drive gear, idler gear, and any bushings.
- Clean all components with solvent and soft bristle brush. Dry with compressed air. Do not use a wire brush on gear teeth or housing bores.
- Inspect housing: Check for cracks, scoring on gear pocket walls, and wear on the drive shaft bore. Any scoring deep enough to feel with a fingernail requires pump replacement.
- Inspect gears: Check gear teeth for pitting, spalling, chipping, or wear. Check gear faces for scoring. Replace pump assembly if any gear damage is found.
- Inspect drive shaft: Check for wear, scoring, or damage at bushing contact areas. Verify spline engagement condition.
- Measure large gear backlash: Install gears in housing. Hold one gear stationary, rock the other gear and measure total movement with a dial indicator. Record reading. Spec: MIN 0.003" MAX 0.013".
- Measure small gear backlash: Same method as large gear. Record reading. Spec: MIN 0.011" MAX 0.019".
- Inspect relief valve: Remove the pressure relief valve plug, spring, and ball/piston. Inspect bore for scoring. Check spring for collapse or fatigue — compare free length to a new spring if available. Clean and reinstall.
- Inspect pickup screen: Clean screen with solvent and compressed air. Inspect for holes, tears, or collapsed mesh. Replace if damaged — a blocked or torn screen is a direct cause of bearing failure.
- Prime the pump with clean engine oil before installation — fill pump cavity and rotate by hand to distribute oil before starting engine.
- Install pump with new O-ring or gasket as applicable. Torque mounting bolts to specification.
- Install new O-ring on oil suction tube. Verify O-ring seats fully in groove before tightening tube bolts.
- Install oil pan with new gasket or RTV as applicable. Torque oil pan bolts to specification.
- Fill with correct oil. Run engine and verify oil pressure at idle and rated RPM.
Required Tools & Equipment
Dial Indicator with Magnetic Base
0.0001" resolution
Gear backlash measurement
Feeler Gauge Set
—
Gear end clearance check
Soft Bristle Brush + Solvent
—
Gear and housing cleaning
Compressed Air
Max 30 psi cleaning
Drying passages and screen
Torque Wrench — 3/8" drive
0–80 ft-lb
Pump and oil pan bolts
Clean Engine Oil (NG Approved)
—
Priming pump before install
Oil Pump Measurements
| Measurement | Factory Spec | Location | Actual Value | Status | Notes | Photo |
|---|
Visual Inspection
Technician Notes — Oil Pump
P
Parts Tracker
All parts installed during this overhaul — included in Customer Report
| Description | Part Number | Qty | Supplier | Condition | Notes |
|---|