Marine Main Engine Exhaust Valve Leakage, Exhaust Temperature & Cylinder Condition Tool

Cylinder EGT • Temperature Spread • Exhaust Valve Leakage Evidence • Compression Pressure • Pmax • Fuel Index • Trend Rate • Scavenge-Normalized Compression • Cylinder Condition

Marine Main Engine Exhaust Valve Leakage, Exhaust Temperature & Cylinder Condition Tool

Screen main-engine cylinders for abnormal exhaust temperature, gas-sealing loss, exhaust-valve leakage patterns and combustion imbalance. Simple mode evaluates one suspect cylinder against engine/reference values. Advanced mode compares every cylinder using current and reference EGT, trend rate, compression pressure, peak pressure, fuel-index deviation, thermocouple confidence and direct valve-leak evidence.

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Fast suspect-cylinder screen: 12 inputs.Use readings taken at stable, comparable load. Temperature alone does not prove exhaust-valve leakage. The tool strengthens or weakens the valve-leak pattern using compression pressure, peak pressure, trend, fuel-index context, thermocouple confidence and direct leakage evidence.

TemperatureMean / reference / trend deviation

PressurePcomp & Pmax comparison

DiagnosisValve-leak evidence + alternatives

Suspect Cylinder Snapshot

Current cylinder exhaust temperature°C.

Engine average exhaust temperature°C at the same stable load.

Healthy/reference temperature for this cylinder°C from sea trial, shop test or known-good comparable-load trend.

Prior temperature reading°C.

Running hours since prior reading

Current compression pressure Pcompbar(g).

Engine/reference compression pressurebar(g) at comparable load.

Current peak pressure Pmaxbar(g).

Engine/reference peak pressurebar(g).

Cylinder fuel-index / load deviation% versus engine average. Positive = more fuel/load command.

Direct exhaust-valve leakage evidence

Exhaust thermocouple confidence

Engine / Reference Basis

Engine load% MCR or comparable load basis.

Engine speedrpm.

Scavenge-air pressurebar(g), common to the test point.

Barometric pressurebar absolute.

Scavenge-air temperature°C, recorded for context.

Reference basis

User-Entered Diagnostic Thresholds

These are screening thresholds, not maker alarm settings. Replace the demonstration values below with the engine maker, vessel SMS or fleet-condition thresholds used for this engine and load range.

EGT review deviation°C vs mean or cylinder reference.

EGT strong deviation°C.

EGT trend review rate°C per 100 running hours.

Pcomp reduction review% below cylinder reference.

Pmax reduction review% below cylinder reference.

Fuel-index deviation reviewabsolute % from engine average.

Maker absolute EGT limit (optional)°C. Enter 0 to disable this check.

Cylinder Condition Register

Enter readings from the same stable operating point. Pcomp/Pmax references should be from comparable load and engine condition. “Valve evidence” is direct observation/testing evidence and is deliberately kept separate from temperature/pressure inference.

Use	Cyl.	Current EGT °C	Reference EGT °C	Prior EGT °C	Hours since prior	Pcomp bar(g)	Ref Pcomp bar(g)	Pmax bar(g)	Ref Pmax bar(g)	Fuel-index dev. %	Valve-leak evidence	Thermocouple

Condition / Verification Checks

Readings taken at steady comparable loadEGT, Pcomp, Pmax and fuel-index data represent a stable point rather than manoeuvring/transient operation. Exhaust thermocouples cross-checkedSuspect temperature channels have been checked against swap test, handheld method or other vessel procedure. Indicator / pressure equipment condition verifiedPressure transducer/indicator cock/PMI system is suitable for cylinder-to-cylinder comparison. Fuel injection condition consideredInjector, fuel pump/control and injection timing remain alternative causes of abnormal cylinder temperature. Gas-sealing alternatives consideredPiston rings, liner condition, cylinder cover/gasket and exhaust valve are considered when compression falls. Common air / exhaust path consideredScavenge-air cooler, turbocharger, ports and exhaust backpressure are reviewed if several/all cylinders move together. Valve actuation / timing checked where relevantHydraulic/electronic actuation, closing, spindle motion and timing are considered for suspect units. Trend and follow-up inspection plan recordedThe condition result will be compared with subsequent readings or physical inspection, not treated as a one-point diagnosis.

Diagnostic boundary: the leakage score is a structured evidence screen, not a probability of failure and not a substitute for the maker’s troubleshooting procedure. High EGT can also arise from injection faults, timing, unequal load, restricted gas flow, air-side problems or a faulty thermocouple. Low compression can also result from piston rings, liner, cylinder cover/gasket or other gas-sealing defects.

Technical basis: cylinder exhaust-temperature deviation is widely monitored as an engine-condition signal, while compression and peak-pressure measurements provide additional evidence about gas sealing and combustion. A leaking exhaust valve can produce rising exhaust temperature and reduced compression, but the same measurements are not uniquely diagnostic. The tool therefore combines multiple relative indicators and direct valve evidence rather than assigning a fault from EGT alone.

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