What are the signs that a wheel bearing has been damaged by a pothole? And how do you inspect a seal on a wheel bearing hub unit?
To answer the first question, when a bearing hits a pothole, it actually causes a small indentation to one of the races. Over time that small indentation causes the grease to have turbulence over that area. This is what’s known as a brinelling mark. It’s where something very hard makes a mark in that race over time as the bearings go over it.
It churns up the grease and that mark can become larger and larger. So over time, this causes noise. This could be three days, or three weeks, or even three months, down the road depending on the vehicle, but the leading symptom is going to be noise coming from the wheel barring.There may be no detectable change in in play, or play in any which direction of the wheel, but it’s going to be very, very, noisy.
As for the second question about how to inspect a seal on a hub unit., the most important thing to remember is that there should be no leaking grease on the seal, especially on a modern hub unit. That may be a Gen 2, Gen 1, or Gen 3. If the seal is leaking, it’s a sign that the outside is coming into the bearing, because if the grease leaks out due to excess heat, which could be caused by brinelling inside of the bearing, it is a sign that the bearing has failed internally.
So any time you see any leaks, or any time you’re installing a wheel bearing, and the seal becomes dislodged from the outer race, the hub unit, or the wheel bearing needs to be replaced.
This video is sponsored by GMB.