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How warm is normal for boat trailer wheel bearings? My trailer is 15 months old, so almost new, and after about 30 minutes driving the hubs are warm to touch. The trailer is for a 4.2m boat, so no great load. The dealer says the wheels spin well, with no noise, so therefore no problem. I took the cap off one hub and confirmed that there was grease in there, although it was a grey colour, not the blue/green I am used to with boat trailer bearings. On a subsequent 2 hour trip, I found the cap had pushed out of the hub and was close to falling off. With further travelling it was still being pushed off the hub. The bearings on my 16 year old trailer are always cold, even with heavy loads.
How warm is too warm?
Why would the cap be pushed off the hub?
Many thanks

Hi there,
One would expect trailer bearings to be lukewarm after a long journey. Heat is the result of friction, so further investigation will be recommended. If they are taper roller bearings, there should be the smallest amount of play present, so the adjustment might need checking to make sure it's not too tight. Also the type of grease is just as important as the amount of grease present. You may wish to clean out all the grease and put some new grease in. The fact the caps are coming off could be a result of the hub heating up and changing size, or the cap has been deformed upon the first removal and needs a bit of adjusting to make it tight again.
Does the trailer have brakes?, this could also be a source of heat if they are sticking.

The dealer recently replaced the hubs and bearings on the trailer and the problem appears to have gone.