How to Tell Whether a Radiator Is Failing
The answer to how to tell whether a radiator is failing usually lies in the machine's own behavior: oil or water temperature climbs above its usual level, performance drops, or wet marks appear under the radiator. In this article we match symptoms to likely causes and show the order in which to run the first checks.
Rising temperature: the earliest warning
Temperature is the data that best shows the health of a cooling system. If, under the same load and similar ambient conditions, you reach a temperature you have not seen before, the radiator is no longer rejecting heat as well as it used to.
A slowly rising temperature generally points to fouling, while a sudden jump points to a fan, pump or flow interruption. To make this distinction, it helps to keep a record of the machine's normal operating temperature; for limit values, always rely on the data from the equipment and radiator manufacturers.
Symptom, likely cause and first check
| Symptom | Likely cause | First check |
|---|---|---|
| Temperature rises over time | Dust, oil or lint buildup on the fins; restricted airflow | Inspect the surface and the air inlet and outlet path visually |
| Temperature jumps suddenly | Fan stopped, pump or valve problem, flow interruption | Confirm the fan is turning, power is reaching it, and there is flow |
| Dripping or wet patch | Loose connection, worn seal, crack in the housing | Wipe the area and watch it cold; find the point the leak comes from |
| Low flow, system working hard | Internal blockage, dirty or aged oil, saturated filter | Check the filter condition and the appearance of the oil; compare the inlet-outlet temperature difference |
| Fan noisy or vibrating | Loose mounting, damaged blade, bearing wear | Check the fan mounting and blades with the fan stopped by hand |
| Recurring crack at the same point | Vibration, rigid mounting, wrong support | Inspect the mounting points and vibration isolation |
Carry out the checks in the table cold and de-energized, taking safety precautions. After finding a suspicious point, it is better to make a single change and watch the result than to hide the real cause with several interventions at once.
Fan and electrical side
In fan-cooled oil coolers, the problem is often not in the radiator itself but in the fan or its supply. For DC fans the voltage (12 V or 24 V), and for AC fans the mains voltage (220 V or 380 V), must match the label. Low voltage slows the fan down, and a reversed direction of rotation disrupts the direction of airflow.
When the fan turns but air does not pass through the radiator, a protective grille, a cover or an incorrectly fitted air duct may also be the problem.
Cracks caused by vibration
Continuous vibration can produce fatigue cracks in soldered and welded areas. The symptom is usually a small, constant leak; it disappears temporarily when wiped clean and then shows up again.
In such a case, sealing the leak alone is not enough. The root cause is that the mounting transmits vibration or that a pipe is straining the radiator. For details on mounting orientation, see the article on radiator mounting and the importance of maintenance.
When is expert help needed?
In the following situations, limit your own intervention and ask for an expert assessment:
- If the leak comes from a crack in the housing or from a weld area
- If the temperature does not drop despite cleaning and a fan check
- If the system is under pressure and a connection needs to be opened
- If the color, smell or fluidity of the oil has changed noticeably
Never work on a system under pressure before it has cooled and the pressure has been released. For regular inspection steps, see the radiator maintenance guide.
Next step
If the fault cannot be repaired or the application conditions have changed, you need to know the equipment's oil flow rate, temperature and working pressure to choose the right replacement. You can see the fan-cooled options on the fan-cooled radiators page, and for product selection and technical information you can contact us.