Normal operation supervision

If an alarm limit is reached and an alarm is activated, the engine situation is already serious. All necessary counter measures must be taken to remove this emergency condition and return to normal operating condi-tions. As the abnormal operating situation may cause damages to the engine, all efforts must be put into returning to the normal operating situation instead of just waiting for an automatic shut down of the engine.

03.6.1 Normal operation supervision, general

Note! There is no automatic supervision or control arrangement that could replace an experienced engineer’s observations. LOOK and LISTEN to the engine.

Strong gas blow-by

Strong gas blow-by past the pistons is one of the most dangerous things that can occur in a diesel engine. If gas blow-by is suspected (e.g.

because of a sudden increase of the lubricating oil consumption) check the crankcase pressure. If the pressure exceeds 30 mm H2O, check the crankcase venting system. If that is in good working condition, pull the pistons!

Operation at loads below 20 %

Operation at loads below 20 % of rated output should be limited to maximum 100 hours continuously when operating on heavy fuel by loading the engine above 70 % of rated load for one hour before continuing the low load operation.

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Idling (i.e. main engine declutched or generator disconnected) should be limited as much as possible. Warming-up of the engine for more than 5 minutes before loading, as well as idling more than 5 minutes before stopping is unnecessary and should be avoided.

03.6.2 Every second day or after every 50 running hours

1 Read all temperatures and pressures and, at the same time, the load of the engine. All temperatures are more or less dependent on the load, and the lubricating oil, cooling water pressures (built-on pumps) are dependent on the speed. Therefore, always compare the values read with those at corresponding load and speed in the Accep-tance Test Records and curves. Guidance values are stated in chapter 01.

The charge air temperature should, in principle, be as low as possible at loads higher than 60 %, however, not so low that condensation occurs, see Fig 03-4.

2 Check the indicator for pressure drop over gas and liquid fuel filters. When the pressure drop over the filters increases, the feed pressure to the engine might become too low and the output of the engine must be decreased. Too high of a pressure drop may also result in deformation of filter cartridges.

3 Check the indicator for pressure drop over the lubricating oil filters. Too large of a pressure drop indicates clogged filter cartridges, which results in reduced oil filtration when the by-pass valve is open.

Reduced oil filtration results in increased wear. Vent filters and, if no improvement, change the cartridges.

4 Check the oil level in the oil sump/oil tank. Estimate the ap-pearance and consistency of the oil. A simple control of the water content: A drop of oil on a hot surface (about 150°C), e.g. a hot-plate. If the drop keeps “quiet”, it does not contain water; if it “frizzles” it contains water. Compensate for oil consumption by adding max. 10 % fresh oil at a time.

5 Check the ventilation (de-aerating) of the engine cooling water system. Check that the leakage from the telltale hole of the cooling water pumps are normal (slight).

6 Check that the drain pipes of the air coolers are open.

7 Check that the telltale holes of the oil coolers and the cooling water coolers are open.

8 Clean the compressor side of the turbocharger by injecting water. See the instruction manual of the turbocharger.

9 Running in diesel mode without pilot fuel injection, check the quantity of leak fuel.

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Condensation in charge air coolers

Example: If the ambient air temperature is 35°C and the relative humidity is 80 % the water content in the air can be read from the diagram (0.029 kg water/kg dry air). If the air manifold pressure (receiver pres-sure) under these conditions is 2.5 bar, i.e. absolute air pressure in the air manifold is abt. 3.5 bar (ambient pressure + air manifold pressure), the dew point will be 55°C ( from diag.). If the air temperature in the air manifold is only 45°C, the air can only contain 0.018 kg/kg (from diag.).

The difference, 0.011 kg/kg (0.029-0.018) will appear as condensed water.

60 50 40 30 20 10 0 10 20 30 40 50 60 70

.01 .02 .03 .04 .05 .06 .07 .08 .09 Water content

Water dewpoint ˚C

(kg water/kg dry air)

Amb air temperature ˚C

P=Air manifold pressure bar abs

P=4,5 P=3,5 P=2,5

P=1,5 f=40

f=60 f=80 f=100

f=Relative humidity %

Fig 03-4 320352

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03.6.3 Once a month or after every 500 running hours

1 Clean the centrifugal lubricating oil filters.

2 Clean the turbine side of the turbochargerby injecting water.

See chapter 15. and the Instruction manual chapter 04. for the turbo-charger.

3 Check content of additives in the circulating water.

4 Keep the injection pump racks clean.

5 Check the cylinder pressuresAt the same time, note the load of the engine. Fuel rack position, turbine speed, charge air pressure and inlet air temperature all offer an accurate estimation of the engine load.

NOTE! Measurement of cylinder pressures without simultaneous measure-ment of the engine load is practically worthless.

03.6.4 In connection with maintenance work

1 Record the following steps and the running hours in the engine log:

· lubricating oil sampling (record also operating time of oil). Lubri-cating oil analyzes without statement of operating time is of limited value (“go - no go” only).

· lubricating oil changes

· cleaning of centrifugal lubricating oil filters

· cleaning of lubricating and fuel oil filter cartridges

· change of parts in connection with maintenance according to chapter 04.

2 Disconnect the electronic equipment according to the in-structions in Appendix 00B., if any welding is performed on the engine.

Keep the return connection near the welding point.

Caution! Welding may, if incorrectly performed, cause serious injury on the electronic engine control system.

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