Temperature changes can significantly impact both sealed and non-sealed wheel bearings, affecting their performance, lifespan, and even leading to failure. Understanding these effects is crucial for proper maintenance and preventing costly repairs.

How Do Temperature Changes Affect Wheel Bearings?

Temperature fluctuations are a major factor in wheel bearing health. Extreme heat can cause lubricants to break down, leading to increased friction and wear, while extreme cold can thicken lubricants, hindering smooth operation and potentially causing damage upon initial movement. Both scenarios can compromise the integrity and longevity of your wheel bearings, whether they are sealed units or require regular greasing.

The Impact of Heat on Sealed Wheel Bearings

Sealed wheel bearings are designed for convenience, with pre-applied grease and protective seals. However, prolonged exposure to high temperatures can still pose a threat.

• Lubricant Degradation: Heat accelerates the breakdown of grease. As the lubricant thins out, it loses its ability to effectively cushion the rolling elements, leading to increased metal-on-metal contact. This friction generates more heat, creating a dangerous cycle.
• Seal Expansion and Failure: Elevated temperatures can cause the rubber or synthetic seals to expand. If the expansion is significant, it can compromise the seal’s integrity, allowing contaminants like dirt and water to enter the bearing. This ingress is a primary cause of premature bearing failure.
• Internal Component Stress: Extreme heat can cause the metal components within the bearing to expand. This expansion can lead to increased internal pressure and stress on the races and rolling elements, potentially causing deformation or even cracking over time.

The Impact of Heat on Non-Sealed (Greaseable) Wheel Bearings

Non-sealed wheel bearings, often found in older vehicles or heavy-duty applications, require periodic greasing. While they offer more control over lubrication, they are not immune to heat’s detrimental effects.

• Lubricant Evaporation and Washout: High temperatures can cause the grease to thin excessively, potentially leading to it being "washed out" from the bearing. This leaves the bearing vulnerable to friction and wear. The grease might also evaporate, reducing its protective qualities.
• Over-Greasing Issues: In an attempt to combat heat, some may over-grease these bearings. This can actually be counterproductive. Excess grease can create drag, generate more heat, and potentially push out existing seals if present, allowing contaminants in.
• Increased Wear Rates: Similar to sealed bearings, the breakdown of lubricant under heat leads to increased friction and wear on the races and rolling elements. This is especially critical during periods of heavy load or high-speed driving in hot conditions.

The Impact of Cold on Sealed Wheel Bearings

While heat is often the primary concern, extreme cold also presents challenges for wheel bearings.

• Lubricant Thickening: Cold temperatures cause grease to become more viscous, or thicker. This increased viscosity can lead to higher initial drag when the vehicle starts moving, putting extra stress on the bearing components.
• Seal Brittleness: Some seal materials can become brittle in very cold temperatures. This makes them more susceptible to cracking or damage when subjected to impacts or flexing, potentially compromising their sealing ability.
• Condensation Issues: Rapid temperature changes from cold to warm can cause condensation to form inside the bearing. This moisture can lead to rust and corrosion on the internal metal surfaces, even within a sealed unit.

The Impact of Cold on Non-Sealed (Greaseable) Wheel Bearings

Non-sealed bearings face similar issues in cold weather, with some unique considerations.

• Initial Start-Up Stress: The thickened grease in cold conditions can make initial rotation more difficult, leading to increased wear during the first few miles of driving. This is particularly true if the vehicle has been sitting for an extended period.
• Lubricant Displacement: While cold thickens grease, the act of rotation can still displace it. If the grease is too thick, it may not flow back into critical areas effectively, leaving parts of the bearing temporarily unprotected.
• Moisture Ingress: Similar to sealed bearings, condensation can form. However, in non-sealed bearings, any existing gaps or worn seals can allow this moisture to enter more readily, exacerbating corrosion issues.

Preventing Temperature-Related Wheel Bearing Damage

Fortunately, you can take proactive steps to mitigate the risks associated with temperature fluctuations.

Maintenance for Non-Sealed Bearings

• Regular Greasing: Adhere to your vehicle manufacturer’s recommended greasing schedule. Use a high-quality wheel bearing grease appropriate for your climate.
• Proper Packing: When greasing, ensure the bearing is packed correctly, avoiding overfilling. This allows the grease to function as intended.
• Inspect Seals: Always check the condition of the seals during maintenance. Damaged or worn seals should be replaced immediately.

General Care for All Wheel Bearings

• Listen for Noises: Pay attention to any humming, grinding, or clicking sounds coming from your wheels. These are often early indicators of bearing wear.
• Feel for Vibration: A wobbly or vibrating sensation in the steering wheel or through the vehicle can also signal a bearing problem.
• Regular Inspections: During tire rotations or brake services, have your mechanic inspect the wheel bearings for play or damage.
• Choose Quality Components: If replacing bearings, opt for reputable brands known for durability and performance.

People Also Ask

### What happens if a wheel bearing gets too hot?

If a wheel bearing gets too hot, the lubricant inside can break down, leading to increased friction and wear. This can cause the bearing to seize or fail completely, potentially leading to a wheel detaching from the vehicle, which is extremely dangerous. Overheating can also damage the seals, allowing contaminants to enter.

### Can cold weather damage wheel bearings?

Yes, cold weather can damage wheel bearings. Extreme cold can thicken the grease, causing increased drag and wear during initial movement. It can also make seals brittle and prone to cracking, allowing moisture and contaminants to enter, leading to corrosion and premature failure.

### How often should wheel bearings be serviced?

For non-sealed (greaseable) wheel bearings, service intervals are typically outlined in your vehicle’s owner’s manual, often coinciding with brake service or tire rotations, perhaps every 10,000-20,000 miles. Sealed wheel bearings are generally considered maintenance-free for their lifespan, but should be inspected for signs of wear during regular vehicle check-ups.

### What are the signs of a failing wheel bearing?

Common signs of a failing wheel bearing include a humming or grinding noise that changes with speed or when turning, loose or wobbly steering, vibrations felt in the steering wheel or floor, and uneven tire wear. If you notice any of these symptoms, it’s crucial to have them checked by a professional immediately.

Conclusion

Temperature changes are an unavoidable aspect of driving, and their effect on wheel bearings, whether sealed or non-sealed, should not