RTG engine overheating: causes and what to check
Record the symptoms first
- Exact alarm text and when it occurred, plus whether the engine derated or shut down.
- Coolant temperature trend, engine-room temperature, ambient conditions and time of day.
- Load and duty before the alarm, and whether other RTGs had the same alarm.
- Coolant level, visible leaks, and the condition of the radiator and fan.
Causes and what to check
| Cause group | What happens | What to check |
|---|---|---|
| Heat rejection | The radiator cannot shed heat | Radiator and charge-air cooler fouling (dust, salt, debris), fan operation and drive, shroud and seals |
| Coolant circuit | Flow or coolant quantity is wrong | Coolant level and leaks, water pump, thermostat, hoses, coolant condition |
| Heat generation | The engine works harder or burns less cleanly | Load, air filter restriction, fuel quality and injection, turbocharger, exhaust restriction |
| Engine-room airflow | Hot air recirculates or fresh air cannot get in | Louvres and ducting, doors and covers, fan direction, spacing from other heat sources |
| Sensors and alarm limits | The alarm is early, late or false | Sensor accuracy and wiring, alarm limit against manufacturer data and site conditions |
Engine-room airflow: the cause that is easy to miss
A radiator can be clean and an engine can still overheat if the air that reaches it is already hot. Blocked louvres, recirculating hot air and covers left closed all raise the temperature around the engine. If several RTGs show the same over-temperature alarm, look at airflow and alarm settings before suspecting each engine.
Check the alarm before the engine
Confirm the reading with a second method, such as a calibrated thermometer or the engine controller's own data. Then compare the alarm limit with the manufacturer's data and your site conditions. A limit that does not suit the site causes repeated alarms and unnecessary stoppages, and a limit that is too high can hide real problems.
Repeated engine-room over-temperature alarms across a group of RTGs were traced to a sensor limit that did not suit the site, combined with poor air circulation, and corrected fleet-wide.
Worked example (illustrative)
| Step | Answer |
|---|---|
| Problem | Several RTGs raised engine-room over-temperature alarms in hot weather. |
| Why 1 | Engine-room air temperature reached the alarm limit. |
| Why 2 | Hot air was recirculating and fresh air flow was limited. |
| Why 3 | Air circulation had not been checked since the layout and covers were changed. |
| Why 4 | The alarm limit and airflow were never reviewed for the site's hot season. |
| Root cause | No review of alarm limits and airflow against site conditions. |
Prevention
- Clean radiators and coolers by condition, not only by hours.
- Review alarm trends monthly and compare RTGs against each other.
- Set alarm limits using manufacturer data and site conditions, and record the reasoning.
- Add a pre-season check of cooling and airflow before the hottest months.
Frequently asked questions
Why does my RTG engine overheat only in hot weather?
Higher ambient temperature reduces the cooling margin. A radiator that coped in cooler months may be marginal when it is fouled, airflow is restricted or the alarm limit is close to normal running temperature.
Can a faulty temperature sensor cause an RTG shutdown?
Yes. A faulty sensor, damaged wiring or an unsuitable limit can trigger a derate or shutdown. Verify the reading with a second method before changing the engine.
How often should an RTG radiator be cleaned?
It depends on dust, salt and debris at your site. Set the interval from inspection results, and shorten it where fouling appears quickly. Follow the manufacturer's guidance as the baseline.
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Last updated 14 October 2026. These guides explain a method and give examples. Always follow your equipment manufacturer's manual, your site procedures and applicable regulations.