After renewal or repair of piston rings or cylinder liners or bearings, the new sliding parts need to fit to mating parts to avoid any abnormal wear. Therefore, the engine should have running in operation step by step as follows:
- Make sure that there is no abnormality by checking according to procedure of ‘Recheckings after initial starting’.
- Speed up to rated speed gradually by manual.
- If not sufficiently warmed up, run the engine until temperatures and pressures to be in normal operating condition and adjust them, if needed.
- Prepare for putting load on the engine (Connect to switch board).
- Load up the engine according to following running-in procedures [See fig. 1].
I. Load up from idle to 25% load gradually for about 20 minutes.
II. Run at 25% load continuously for about 30 minutes.
III. Load up from 25% to 50% load gradually.
IV. Run at 50% load continuously for about 50 minutes.
V. Load up from 50% to 75% load gradually.
VI. Run at 75% load continuously for about 50 minutes.
VII. Load up from 75% to 100% load gradually.
VIII. Run at 100% load continuously for about 40 minutes.
- After running-in, the engine can be in normal service mode.
The purpose of running-in is to fit the sliding surfaces for various load cases, therefore, do not run the engine with continuous load in initial stage. In case of piston overhaul, running-in is also necessary to refit new position of piston rings.
Running-in can be done by using normal lubrication oil and fuel oil of either distillate or heavy fuel.