Changing a Thruster Cartridge Seal

View example cartridge seals.

Cartridge seals are universal and fit on any shaft.

Replacing a cartridge seal requires removing the propeller.

To remove a cartridge seal, first remove the propeller following the instructions.

Next, grasp the cartridge seal and slide it off of the shaft. You may need to twist it a little to remove it.

To install a cartridge seal, make sure the O-ring and thruster tube are clean. Slide the cartridge seal over the shaft and make sure it seats. You will note a small amount of grease will be pushed out of the cartridge seal by the shaft. This is normal and the grease can be wiped away with a paper towel or rag.

Each cartridge seal has an index line that is aligned with a small hole that allows the oil to reach the shaft and lubricate the seals on each end of the cartridge. For maximum life, horizontal cartridge seals should be aligned so that the index line is pointing downward. The alignment of the vertical cartridge seal does not matter.

Note that the cartridge seals have a small white washer inside the end closest to the propeller. New cartridge seals include the washer, but you should check to make sure it is there when installing a new cartridge seal.

Old or New?

Current cartridge seals have a light blue tint. Older cartidge seals were green and will not fit on the Pro 4. Do not try to force an older green cartridge seal onto a Pro 4 shaft.