Diagnosing a faulty wheel bearing can sometimes be tricky. Unlike other car components, wheel bearings don’t always present with obvious symptoms like excessive play in the wheel when you grab it. Many Subaru owners, and drivers of other vehicles, often find traditional methods of checking for wheel bearing issues unreliable, especially when trying to diagnose the problem while the bearing is still on the vehicle. This is where a simple infrared temperature gun can be a game-changer for Car Wheel Bearing Diagnosis.
For those struggling to confirm if a wheel bearing is failing, especially when noises are subtle or difficult to pinpoint, this guide provides a straightforward method using a temperature gun. This technique has proven highly effective in identifying problematic wheel bearings by detecting temperature differences.
Here’s how to diagnose car wheel bearings using a temperature gun:
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Drive to Warm Up the Vehicle: Begin by driving your vehicle to bring it up to its normal operating temperature. This ensures the bearings are also at a working temperature, which is crucial for accurate readings.
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Measure Hub Temperature with an Infrared Thermometer: Using an infrared temperature gun, aim the laser as close to the wheel bearing hub as possible. For steel wheels with exposed axle stubs, target the stub directly. If you have aluminum wheels, you can typically pop off the center cap for access. Alternatively, for a quick check through aluminum wheels, aim through the wheel slots towards the rotor near the hub/bearing. Take multiple readings (around 5) to get an average, noting the highest and lowest temperatures, as rotor temperatures can vary significantly from the center outwards.
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Compare Readings Across Hubs: Once you have readings for each wheel hub, compare them. The key indicator of a failing wheel bearing is a significant temperature difference between sides.
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Identify the Faulty Bearing: In most cases, a temperature difference of 20-50 degrees Fahrenheit or more suggests a problem. The wheel bearing on the side with the higher temperature is likely the one that is failing. In the example below, the passenger side reads 96 degrees Fahrenheit, while the driver’s side is significantly hotter at 127 degrees. The rear bearings are much cooler at 74 degrees. This indicates a likely issue with the driver’s side front wheel bearing.
Important Consideration: Before diagnosing wheel bearings, ensure that your brakes are not dragging or seized, as brake issues can also cause elevated hub temperatures. Rule out brake problems to ensure accurate wheel bearing diagnosis.
In the vehicle diagnosed in the images, the subtle growling noise was only noticeable after snow tires were installed, making it difficult to distinguish between tire noise and a wheel bearing issue. This temperature method provides a clear and definitive diagnosis even when auditory symptoms are ambiguous.
This temperature check method provides a quick, reliable, and non-invasive way to perform a car wheel bearing diagnosis, saving time and guesswork in automotive maintenance. It’s a practical approach for both DIY enthusiasts and professional mechanics.
