What Causes Grease On the Inside of Boat Trailer Wheels

Published 05/28/2016

Question:

I recently replaced both inner/outer bearings, and rear seals, on my boat trailer this has been less than 6 months ago. Before each trip to the lake I would squirt a little marine grease into the port on the bearing buddy. I just noticed that grease was being expelled from the back side of the hub when I went to trailer my boat. A guy there said that I had blown my rear seals on the hubs which I recently replaced as mentioned above. He told me that I was greasing my bearing too much, thus causing the rear seal to blow out. Any truth to this? I am going to replace JUST the rear seals on the hubs, however I just want to make sure that this over greasinginch is in fact what the issue is. Please give me some insight on this?

asked by: Donald W

Helpful Expert Reply:

The guy you were speaking with was telling the truth. If the Bearing Buddies are overfilled, you will indeed blow out the grease seal. The excessive pressure will push the grease out through the rubber portion of the seal. Using a double lip grease seal that has a radial spring inside it which makes the rubber seal grip the spindle more tightly can help reduce the likelihood of the seal blowing out. Also, when adding grease, pay close attention to the piston surrounding the grease zerk. As the grease fills the hub cavity, the piston will move outwards. When it's extended fully, and the spring is compressed (see photo), the hub is full.

How did I learn this? Two days after I got my PWC trailer many years ago, I did the same thing you did. I've linked you to our selection of double lip grease seals.

expert reply by: Mike L