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How to Install Marine Bearing Seal

by | Dec 2, 2018 | Technical Guides | 2 comments

Easy Steps to Install a Marine Bearing Seal Correctly

Grease is applied to a marine seal and bearing for one reason only: to reduce friction. Friction produces heat, and excess heat, through incorrect installation, destroys bearings.

Wow, you said I must apply marine bearing grease to lubricate the seal!

If you own a boat trailer, this is the most important video you must view to help prevent being stuck on the side of the road.

Is it true that poor installation practices reduce the life of bearings by up to 40%?

Watch the video and discover how to correctly grease your seals and extend the life of your bearings.

Australian Marine Bearing Seals

Rubber marine seal and stainless outer ring

  1. Firstly, applying grease to the Australian marine seal significantly reduces heat-causing friction. Surprised?
  2. Secondly, the ID of a Marine grease seal is a shrink-fit and very tight fit on an axle.
  3. Thirdly, the ID of a marine seal does not spin; only the steel OD of this seal spins.

The connection between the rubber seal and the stainless metal housing creates friction.

The rubber seal has two lips on the inside. Apply ample grease to these lips to significantly reduce friction and increase bearing life.

As a result, water ingress does not continue to be a significant problem.

In 90% of cases, marine grease is not applied to the inner lip of a marine seal. Grease prevents air from being sucked into the bearing cavity when the hot wheel hub is immersed in the cold seawater.

A greased marine seal provides an additional barrier to help prevent water ingress. It also offers corrosion protection.

Oil Seal

Proper installation of any seal requires lubrication on the machined steel surface.

Couplemate sells NSK bearing kits and seals.

Bearing Buddies

Can the over-lubrication of bearings by boaties fix the water problem in the grease? How?

New grease pushes the old marine bearing grease through the back grease seal.

axle JackThis method is dangerous and should be avoided.

  1. The ideal amount of grease in your bearing cavity is approximately 50%.
  2. As the bearing cavity heats up, excess grease spills over the inside of your wheel.
  3. Excess grease is ‘flung’ onto the road surface during transit.
  4. Grease stains on the springs, wheel rims and undercarriage of your boat trailer are almost impossible to clean.

Inspect every bearing set for carbon black in the grease, then correct the adjustment.

On one occasion, I was preparing my boat to return home to Brisbane at the Hawkesbury River. While checking the bearings, I found one bearing journal so worn that it would not have successfully made the trip back.

Disaster saved me from checking my bearings before the long trip home.

Buy Australian Made Replacement Galvanised Dic Rotors below

Frequent Bearing Checks

Increasing the frequency of bearing checks reduces disasters.

Over time, the outside casting on your bearing wears, creating carbon black. Worn bearings also cause heat and accelerate bearing failure.

Are your bearing buddies being stolen? Maybe they are not being taken, find how why.

Please leave a comment if you found the above tips helpful. I would love to hear from you if you find errors or disagree.

Finally, another good article is on why caravan and boat bearings fail.


  1. BoatMate Trailer

    What a great site, glad I found you. You’ve already provided some great advice!

  2. Alan Murrie

    While checking the bearings, I found (on) ONE bearing journal so worn; it would not have successfully make the trip back.
    I guarantee you bearing failure IF you expect your bearings to last forever and ignore critical checks.


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