Issue with Bearing Buddy Leaking Grease from Overfill Port

Question:

I put bearing buddies on a travel trailer,with rubber caps. I usually just ran short trips up to 200 miles. Recently I traveled down the blue ridge from Virginia to Georgia, stopping and camping every 30 - 50 miles, staying from 2 to 7 days. During that trip we had some freezing weather. Grease began coming out of one bearing buddy, from the overfill relief port. The port was barely covered with the rubber cover. Before the end of the trip, 3 bearing buddys were doing this. The 4th only let out 2 small spots I wish I could send pictures, but cant. I removed the bearing buddys after deciding they would do more harm than good. My opinion is that the grease expanded. I often check the hub temperatures when traveling, and they never got hot. I never had to do any heavy braking that would cause extreme heat. Have you ever heard of this or can you explain why this happened?

asked by: David

Expert Reply:

Generally speaking bearing grease has so little water in it that significant expansion due to freezing temperatures is unlikely. Higher operating temperatures within the hubs while underway would potentially thin the grease but again not cause much in the way of expansion of its volume.

Typically Bearing Buddies are used on boat trailers to keep water out of the hubs. Since boat trailers are not often used in extreme cold weather this may be why we have not heard of thermal issues like this.

The most likely cause for the seepage of grease out of your Bearing Buddies is overfilling. There seems to be a natural tendency (for all of us!) to think: "if some grease is good, more must be better".

I suggest you take a look at your grease seals and brake assemblies to make certain that no grease has found its way into your drums and brake pads. Grease on your pads will require you to replace them - and the inner grease seals as well if the pressure from the Bearing Buddies has blown them out.

In your particular case I think you did the right thing by removing the Bearing Buddies and replacing them with standard grease caps.

expert reply by: Adam R