Table of Contents
Exhaust temperature running high or low means different things when one unit is affected versus all units. This page lists the reasons and the actions for each case, for both high and low exhaust temperatures.
Reasons and actions for all unit and single unit exhaust temperature high and low
Exhaust temp. Low in all unit
- Low load of the engine
- High scavenge air pressure and low scavenge air temperature allows more supply of scavenging air which promotes optimum combustion of fuel oil and no unburnt fuel remains
- Early ignition results in high thermal efficiency and reduced exhaust temperature
- Fuel timing has been advanced due to wrongly set fuel pump, incorrect fuel injector timing.
- Fuel oil booster pump pressure low
- Fuel regulating shaft stuck at minimum position
- Fuel oil filter chocked or dirty
- Water content in fuel
Reasons for Exhaust temperature Low in Single unit
- Faulty pyrometer.
- Scavenge air pressure high.
- Scavenge air temperature low
- Fuel oil high-pressure pipe leaking
- Faulty fuel injector, needle stuck up in the injector
- Fuel timing has been advanced due to wrongly set fuel pump, incorrect fuel injector timing.
- Fuel regulating shaft stuck at minimum position
Action
- Inform bridge
- If possible, increase the rpm
- Check scavenge air temperature, if it is too low adjust by opening SW recirculating valve
- Check fuel oil for water content
- Check fuel oil filter if differential pressure high then change over to stand by filter and clean the dirty one
- Check pressure regulating valve
- Check fuel rack position
- Check fuel oil injector and check whether the needle is stuck up or not
- Check for any steam leakage from the heater
Exhaust temp. high in all unit
- Insufficient supply of scavenging air
- High scavenge air temperature due to faulty air cooler
- In case of late ignition, power is lost since the fuel is not burned correctly to transmit power at the most effective part of the stroke. Combustion may continue during the expansion stroke and may be incomplete, giving loss in energy produced, high exhaust temperature, and smoke.
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- excessive injector spring setting,
- poor atomization,
- high viscosity or poor quality fuel,
- incorrectly timed fuel pump,
- ow compression pressure due to chocked scavenge port, the air is escaping past piston during compression
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- Engine overload due to hull fouling, propeller obstacle, or bad weather
- Scavenge fire
- Early opening of the exhaust valve
- Fouling of T/C
- Poor quality of fuel used and improper purification
- Fuel regulating shaft stuck at maximum position
Exhaust temp. high in one unit
- Faulty pyrometer
- Leaky exhaust valve
- Early opening of the exhaust valve will cause a loss in power since pressure is released too soon (due to the loss of heat energy in the combustion chamber, this energy will increase exhaust temperature).
- Specific unit’s scavenge port dirty, so less amount of scavenging air is delivered thus scavenge pressure low
- Scavenge fire in a specific unit
- In case of late ignition, power is lost since the fuel is not burned correctly to transmit power at the most effective part of the stroke. Combustion may continue during the expansion stroke and may be incomplete, giving loss in energy produced, high exhaust temperature, and smoke.
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- excessive injector spring setting,
- poor atomization,
- high viscosity or poor quality fuel,
- incorrectly timed fuel pump,
- low compression pressure due to chocked scavenge port, the air is escaping past piston during compression
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Action
- Inform bridge
- Check and adjust scavenge air pressure and temperature
- Check and adjust fuel viscosity, injector, pump.
- Check fuel regulating shaft position
- Reduce RPM if bad weather exists.
Reasons For Abnormal Smoke in exhaust
- Overloaded running condition
- Scavenge fire
- Increase fuel temperature or fuel viscosity
- After burning
- Contaminated fuel
- Too low turbocharge RPM
- Injector fuel not atomizing the fuel completely
- Compression pressure too low due to leaky piston ring or exhaust valve