HOW TO GREASE AN OUTBOARD JET

How to Grease an Outboard Jet

An outboard jet engine can handle a great deal of abuse. However, there is one maintenance item that, if ignored, can result in a complete failure of the jet lower assembly. That item is the main bearings for the driveshaft in the jet pump.

Those bearings require a specific water-resistant grease after each and every use. Every time the pump is submerged you must add new grease to the bearings to expel any moisture.  

Thankfully, the Outboard Jet lower unit comes with an easy to access zerk fitting on the side of the pump, which is accessible without the need for any tools or disassembly. This zerk fitting is sealed with a rubber vent hose and is used to grease the driveshaft bearings inside the pump housing.

To properly grease an Outboard jet engine, you will need a low-pressure hand pump grease gun. This is a critical component that should not be skipped. Using the wrong grease gun will blow the seal out which will lead to premature damage. DO NOT USE A LEVER-TYPE GREASE GUN.  

The grease for lower pressure hand pump style grease guns as described above are like toothpaste. As grease is used from the tube you will need to slide the grease inside the pouch up towards the top. One method I prefer is, like toothpaste tubes, I fold the bottom over onto itself and use a wood clamp to hold it in place.

DO NOT USE AN ALL-PURPOSE MARINE GREASE. 

The type of grease to use in an Outboard Jet is Quicksilver or Mercury 2-4-C. The previous grease type specified was Lubriplate 630-AA. You may still see this grease type specified in older manuals, but the type specified by the manufacturer was changed in a notice published on their website in March 2015.

1. Remove the vent hose from the zerk fitting on the side of the jet.

2. Place a clear sandwich bag over the vent hose outlet and zip it closed.

3. Pump grease into the fitting on the pump using the low-pressure grease gun until old grease is forced out of the tube.

4. Continue pumping until excess grease starts to exit the vent hose into the bag.

5. Remove the bag from the outlet tube and inspect it for moisture. A small bit of water is normal. The objective is to purge any moisture from the bearings to prevent damage.

6. Reconnect the vent hose onto the grease fitting.

Inspecting the contents of the sandwich bag each time will give an indication of the conditions inside the bearing housing. An increase in the moisture content purged each time is an indication that the seal is beginning to leak. If the grease becomes a dark gray color the driveshaft bearing should be inspected.

On the opposite side of the jet pump from the grease port, there is a small weep hole. This hole is useful to determine if the bearing seal is properly functioning. If you see grease coming from this hole then unfortunately one of the grease seals has failed. This doesn’t mean you can’t use the jet anymore but you need to focus on having the seal and possibly the bearings replaced. If the seal has failed you will need to diligently purge water from the pump each time you use it.

Regularly greasing the Outboard Jet pump will keep the bearing operational for years. Making it part of your routine to add grease after each will let you know the moment you experience any issues with seal failure.