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Diagnosing Causes of High Exhaust Gas Temperature in Marine Engines

1. Increase in Engine Load-The fouling and the deformation of the ship's hull can increase resistance to a fairly great extent; liable to increase the engine load.
Damage to propeller blades due to drifting wood or going aground, can subject the engine to an increased load.
2. Fuel Valve/Supply -Exhaust gas temperature rises due to the enlarged nozzle hole of the fuel injection valve due to poor maintenance or inferior HFO supply.
3. Exhaust Valve Passing-Valve head or seat badly damaged/worn causing blow-by of exhaust gasses on combustion.
4. Fouling of Exhaust Gas Passageways-Combustion products build-up on the turbocharger nozzle and the surface of turbine blades, clogging the exhaust gas passage and reducing turbocharger efficiency.
Clogging also increases back-pressure in the passageways to the turbocharger, restricting the efficient removal of the gasses.
5. Fouling of the Scavenge Air Passageways-Fouling of the air-side due to oil mist on suction casing and the diffuser of the turbocharger.
Clogging of cylinder liner scavenge port by combustion products.
6. Leakage of the Scavenge Air.-Scavenge air supply can leak between the turbo-blowers and scavenge tableau, decreasing air supply pressure to ports.
7. Scavenge Fire-A fire occurs in scavenging chamber due to build-up of lube-oil being ignited by a spark from a blow-by of piston rings
8. Insufficient /Unsatisfactory HFO Treatment.-HFO requires extensive treatment through filtration, heat exchangers and centrifuging to remove water and particles.
9. Insufficient Air Supply to Blower-Blower compressor suction filters clogged
Insufficient air supply to blower
10. Exhaust Valve Timing Problem-This can be caused by timing gear slipping of hydraulic/pneumatic supply to operating components

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