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Project

30K Top Overhaul of EMD 12-645-E9B Main Engine for Drilling Rig in India

Table of Contents

Background

Industry
Oil & Gas
Solution
30K Top Overhaul (TOH) of Main Engine
Make & Model
EMD 12-645-E9B
Main Engine
Asset
Drilling Rig

Summary About The Project

Neptunus successfully completed a 30K top overhaul of an EMD 12-645-E9B main engine on a drilling rig operating in the Tapti Field, India. The engine had accumulated approximately 179,387 running hours, and the overhaul was carried out as part of the OEM-scheduled maintenance program.

Prior to dismantling, oil leakages were observed from the turbocharger assembly, rear end, and camshaft drive housing. A crack in the crankcase was also identified during inspection.

The overhaul included inspection, renewal, calibration, and reassembly of major engine systems. Critical work included power pack fork and blade renewal, injector replacement, rocker arm and valve bridge renewal, connecting rod bearing renewal, camshaft bearing renewal, main bearing and thrust collar renewal, governor replacement, lubrication and cooling system servicing, turbocharger and aftercooler renewal, and overspeed trip assembly renewal.

Comprehensive pre-commissioning checks and safety shutdown tests were carried out before the engine was returned to operation. Load trials were conducted up to 1,400 kW at approximately 905 RPM, with engine operating parameters and exhaust temperatures monitored throughout the trial. All recorded load trial observations were marked satisfactory.

Planning

  • Team Composition: Neptunus team led by the Team Leader with rig technical support
  • Duration: 22 February 2026 to 31 March 2026
  • Work Scope:
    Complete 30K top overhaul including dismantling, inspection, cleaning, calibration, component renewal, reassembly, pre-commissioning, safety testing, and load trials.

Procedure Carried Out

1. Power Pack Assembly:
  • Removed the existing power packs and shifted them to the compressor room
  • Renewed all power pack forks and blades
  • Renewed all cylinder test valves
  • Reused cylinder head mounting crab bolts after inspection
  • Matched power pack baskets with their respective fork rods during assembly
  • Assembled power packs according to EMD guidelines
  • Checked lateral play of the lower bearings after tightening
  • Renewed all water jumper lines
2. Fuel Injection System:
  • Installed new fuel injectors
  • Reused injector clamps and bolts after inspection
  • Applied OEM-recommended torque during injector installation
  • Renewed needle bearings, clevis pins, and retainers in the fuel injector linkages
  • Calibrated fuel injector rack settings according to EMD recommendations
  • Calibrated injector height settings according to OEM requirements
3. Rocker Arm and Valve Mechanism:
  • Renewed all rocker arm assemblies
  • Renewed all valve bridges
  • Applied OEM-recommended torque during assembly
  • Adjusted valve lash settings according to EMD recommendations
4. Fuel Control and Governor System:
  • Renewed the governor assembly with new gaskets
  • Filled the governor with fresh oil
  • Renewed needle bearings, clevis pins, and retainers in the fuel injector linkage system
  • Checked and calibrated injector rack and height settings
  • Reused the governor drive after inspection
  • Installed the renewed governor assembly using a new gasket
5. Starting Air System:
  • Removed both air starters
  • Cleaned and inspected the air starter assemblies
  • Reused the air starters after inspection
  • Inspected the downstream air system, filters, valves, and hoses as part of the overhaul scope
6. Engine Breathing System:
  • Removed and cleaned the oil separator
  • Installed a new separator gasket and element
  • Reassembled and refitted the separator assembly
7. Camshaft and Bearings :
  • Removed the upper camshaft bearing caps
  • Dismantled and cleaned the camshaft
  • Removed and cleaned the lower camshaft bearings and bearing blocks
  • Cleaned and inspected the camshaft
  • Reinstalled the camshaft on both left and right banks
  • Renewed all upper and lower camshaft bearings
8. Crankshaft and Bearing System:
  • Renewed all upper and lower main bearings
  • Renewed the thrust collar
  • Checked thrust clearance
  • Confirmed thrust clearance within permissible OEM limits
  • Renewed all upper and lower connecting rod bearings using PowerRail spare parts
  • Applied OEM-recommended tightening torque
  • Crank pin journal dimensions were measured and recorded within the specified new-part range of 165.05 to 165.10 mm
9. Lubrication System:
  • Renewed the main lube oil pump assembly with gasket kits
  • Renewed the scavenging pump and mounting gaskets
  • Reassembled the lube oil cooler with a new gasket
  • Renewed oil filter elements
  • Renewed turbocharger oil filter elements
  • Renewed fuel filter elements
  • Renewed fuel lines and rocker arm oil lines
10. Cooling Water System:
  • Renewed both left and right bank water pumps
  • Renewed water pump mounting gaskets
  • Cleaned and inspected the cooling water manifolds
  • Renewed cooling water manifold seals and gaskets
  • Recorded upper and lower liner pilot bore measurements
  • Renewed hand hole cover seals
11. Turbocharger and Aftercooler:
  • Renewed the turbocharger assembly with a UTEX unit
  • Renewed and installed the aftercooler core
  • Applied tightening torque according to OEM recommendations
  • Inspected the turbocharger-to-aftercooler connection
  • Compressor air leakage at the turbocharger-to-aftercooler joint was sealed by the rig crew using M-Seal
12. Air Duct and Exhaust Manifold:
  • Removed and cleaned the air duct
  • Dismantled the exhaust manifold
  • Renewed exhaust leg gaskets
  • Renewed exhaust manifold bellow gaskets
  • Conducted exhaust manifold mounting and leakage checks
13. Engine Block and Crankcase:
  • Thoroughly cleaned and visually inspected the engine block
  • Recorded upper and lower liner pilot bore measurements
  • Renewed hand hole cover seals
  • Inspected the crankcase
  • A crack in the left bank oil pan was identified and re-fabricated by the rig welder according to the EMD welding procedure
14. Overspeed and Safety System:
  • Renewed all overspeed trip assemblies
  • Applied OEM-recommended torque
  • Reused the crankcase pressure detector assembly
  • Checked all installed safety cutouts with rig personnel
  • Tested crankcase pressure shutdown
  • Tested engine overspeed shutdown
  • Tested low lube oil pressure shutdown
  • Tested jacket cooling water high-temperature alarm
15. Valve Timing and Calibration:
  • Checked valve timing on both camshafts before dismantling
  • Rechecked valve timing after completion of the overhaul
  • Confirmed exhaust valve timing within the EMD recommended range of 104° to 110°
  • Power pack compression testing was not carried out because all power packs were replaced with new units
16. Pre-Commissioning and Load Trials
  • Completed jacket water charging and bleeding
  • Completed fuel system priming and bleeding
  • Inspected the crankcase before startup
  • Completed lube oil priming
  • Verified lube oil circulation through rocker arms, main bearing shells, and connecting rod big-end bearing shells
  • Checked lube oil sump level
  • Attended and checked leakages
  • Completed electrical checks
  • Tested all safety shutdown systems
  • Conducted no-load and load trials
  • Load trials were conducted at multiple operating conditions up to 1,400 kW at 905 RPM
  • Monitored lube oil temperature, lube oil pressure, fuel pressure, water temperature, charge air temperature, and other operating parameters
  • Exhaust gas temperatures were recorded for all 12 cylinders during the load trial
  • All recorded load trial observations were marked OK

Scope for Improvement

  • Replace the fuel pressure gauge because the gauge glass is not clear enough for reliable reading
  • Install an external pyrometer because engine RPM is currently checked manually using a tachometer
  • Provide the required main bearing tool set onboard
  • Provide an offset ¾-inch drive ratchet for loosening main bearing cap nuts
  • Provide a 1-ton chain block for engine overhaul activities
  • Maintain suitable maintenance tools and lifting arrangements onboard
  • Ensure adequate lighting in the engine room, particularly above Engine No. 3
  • Install insulation covers on the exhaust manifold and exhaust gas outlet bellow
  • Repair damaged threads on the rear-end camshaft drive housing
  • Maintain adequate emergency spare parts onboard

Recommendations

  • Monitor engine performance closely during the first 100 operating hours after overhaul
  • Keep a close watch for abnormal sounds, vibrations, leakages, and operating parameters
  • Change lube oil filters after the initial 100 operating hours
  • Inspect the lube oil filters for abnormal particles
  • Carry out lube oil analysis after the first 100 operating hours
  • Change the lube oil immediately if the analysis indicates abnormalities
  • Follow the maker's recommended engine starting and stopping procedures
  • Closely monitor lube oil pressure and jacket cooling water temperature
  • Monitor the engine for fuel dilution and check fuel condition regularly
  • Replace both bank water manifolds during the upcoming overhaul
  • Replace aftercooler housing and adaptor bolts
  • Replace the governor and governor booster
  • Replace the crankcase pressure detector
  • Renew the required fuel control linkage components
  • Replace fuel injectors for units No. 1, 2, 3, 4, 6, 7, and 8 as recommended for the next maintenance
  • Plan the next scheduled 60K maintenance as per OEM recommendations

Conclusion

Neptunus successfully completed the 30K top overhaul of the EMD 12-645-E9B main engine for a drilling rig operating in the Tapti Field, India. The overhaul involved systematic inspection, component renewal, calibration, reassembly, safety testing, and pre-commissioning checks in accordance with EMD OEM recommendations.

Major activities included renewal of power pack components, injectors, rocker arms, valve bridges, connecting rod bearings, main bearings, camshaft bearings, governor assembly, lubrication and cooling system components, turbocharger, aftercooler, and overspeed trip assemblies.

The successful completion of pre-commissioning checks, safety shutdown testing, and load trials, with recorded operating parameters and exhaust temperatures marked satisfactory, confirmed stable engine operation following the overhaul. This project demonstrates Neptunus’ capability in delivering comprehensive EMD engine overhaul services for offshore drilling applications in India.

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