be_ixf;ym_202009 d_22; ct_50

In-Situ X-Y milling on badly damaged main engine guide rails

Mitsubishi 6UEC52LA casualty restored in only 10 days

A 7,934 DWT refrigerated cargo vessel experienced a sudden main engine casualty after an oil mist detection alarm sounded during engine start up. Upon initial inspection, a damaged crosshead bearing and broken screw were found.

At the ship manager’s request, Goltens immediately dispatched their In-Situ Machining Supervisor together with their Technical Manager to check the main engine guide shoe condition. Goltens’ inspection revealed severe and deep scoring all along the length of the guide shoe support rails on 3 cylinders as well as serious damage to the guide bearings.

As Mitsubishi’s authorized service partner, Goltens was requested to provide a comprehensive solution to repair and restore the engine to service while in a scheduled yard period in China with an aggressive completion schedule to minimize the vessel’s downtime.

Goltens’ In-Situ specialists modified their in-situ X-Y milling machinery in their workshop to fit within the engine crankcase. After modification at Goltens workshop, the tools were immediately transported to vessel engine room where Goltens’ diesel specialists had dismantled the damaged cylinders.

  • Adjusting the X-Y Milling machine inside the engine

  • Machining of deeply scored guide rails in progress

  • Close up view of scoring and machining

  • XY Milling in process

  • Milling in-process with deep scores removed

  • Finished guide rail ready for reassembly


Vessel type: Refrigerated Cargo Ship
Tonnage: 7,934 DWT
Main Engine: Mitsubishi 6UEC52LA
Power: 7,061 KW


  • Machining Cylinder No. 1 FWD & AFT guide rail port side to -2.50mm undersize and starboard side to -0.75mm undersize
  • Machining Cylinder No. 2 FWD & AFT guide rail port side to – 1.50mm undersize and starboard side to -1.00mm undersize
  • Machine polishing Cylinder No. 3 FWD & AFT guide rails for Port side and STBD side
  • Rebabbitting of the 12 guide shoes for Cylinders 1 and 2
  • Rebuilt Cylinder Numbers 1, 2 and 3 after machining
  • Commissioning test and successful sea trial


Goltens’ Diesel, Rebabbitting and In-Situ Machining service teams completed the entire job within 10 days, inclusive of workshop preparation and mobilization work. This was a full week earlier than committed to the owner significantly reducing the downtime and expense for the owner.

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