For the jet ski parts referenced, we will be using all WSM parts unless clarification is given.
Jet pump maintenance is an often overlooked aspect of owning a jet ski, and like owning a trailer and having trailer bearings replaced, jet pump bearings need to be replaced as well. Issues that can arise if not maintained is water infiltration, loss of lubrication, bearing wear, and of course total bearing failure where the driveshaft seizes up all together. When water infiltration in the jet pump happens, the grease is then displaced and lubrication is minimized. Because of this, the bearings will start to rust, overheat, and eventually fail.
Depending on your year of Yamaha VX you could have 1 of 2 different jet pump designs (2020 has a single piece pump design with the wear ring integrated into the pump). With either design the process is basically the same.
Tools Needed
-Blow Torch
-12 Ton Press
-1 1/16″ Wrench
-Vice
-Allen Key Set
-Impact Gun
-Driveshaft Holding Tool
-Bearing Press Tools
-1/2 Socket Set
Where To Start?
To start this process first we must remove the pump.
For 2016-2019 the process is the same, we can just remove the rear bucket (2 12mm bolts on the side and then push it out of the way)
Remove the cone (2 12mm bolts on the top and bottom of the cone, then push out of the way. Keep the 10mm for the steering attached as they tend to break depending on the level of salt corrosion).
Then remove the 2 12mm for the pump hanging bracket, and then the 4 14mm bolts for the pump
Once removed you should be able to pull the pump out of the wear ring housing (Some may require more creativity as they can be well sealed, and you may need to use a ratchet strap or something else to help pull it off the jet ski.
2020 pumps are exactly the same to remove, except for the fast that you have to remove the whole pump with the wear ring
To do this there are 5 bolts in the back that have to be removed, in addition to the hanger bracket mentioned before.
After this the pump should come out with the driveshaft attached.
Disassembling The Jet Pump
Disassembling the pump itself is a bit of a process.
First we need to remove the nose cone. To do this there are 3 allen key bolts that must first be removed. After the allen bolts are removed, there is a tab on the side of the cone that a flathead screw driver can fit in. Use this to carefully pry the cone off the pump. Do not score the mating surface of the cone. If it is not budging, you can carefully tap the nose cone with a hammer (not hard), to try and break up any corrosion that is keeping it in place (carefully, you do not want to break the cone).
With the cone now off, we have access to the inside of the pump, where you will see a large nut.
Next is to remove the impeller.
If the jet pump isn’t to old or corroded, sometimes you can easily get the impeller off just by heating up the impeller with the torch (don’t leave in one spot, you just want to get it warm to make it easier to break loose), and then put the close end of the 1 1/16″ on the impeller, and get your impact gun on the nut on the other side. You want to have the impact hit the nut clockwise (the impeller is a righty loosey thread). The can get the impeller off easily without too much effort if it’s not stuck on.
The alternative and safer way (which won’t damage the nut threads if stuck on)
is to use a bench vise, driveshaft tool, and the 1 1/16″ wrench
Again heat up the impeller with the torch
put the end of the driveshaft in the driveshaft holding hex tool, and then clamp it together in the vice
You are then going to use the 1 1/16″ wrench to turn the impeller clockwise loosening the impeller (this may take some torque if it is stuck on).
Pressing Out The Bearings
Once the impeller is off, we can press out the bearings
The easiest way to do this is to use a 12 ton press (The one from harbor freight works just fine).
First remove the nut from under where the nose cone used to be on the pump (you will need an impact wrench to do this)
Place the pump with the driveshaft facing up on the pressed
We will press directly down onto the driveshaft, pushing the shaft along with the bearings out the bottom of the pump
Once done you will have a shaft with 2 bearings and a sleeve in the middle at the end.
We will then use the press again,
pressing the driveshaft out of the bearings
Put the bearing end of the driveshaft on the top (where the threads are)
we will press down on the threaded end, pushing out the driveshaft.
This will leave us with a sleeve (we will reuse, and 2 bearings).
Cleaning Up The Pump
We now need to clean beforehand for the new bearings and grease
We first need to clean all the old grease out (feel free to use brake clean, or whichever cleaner that is aluminum safe for this method of grease cleanup)
After the grease is gone, we will clean the mating surfaces (For this a green scotch brite pad is great, just something to remove any corrosion or residue to prep for assembly).
We will also do the same to the driveshaft to remove anything that may cause sealing issues.
Assembly
Assembly starts by pressing in the 2 oil seals provided in our bearing kit
We use Part # 003-627 from WSM
These oil seals will go under the impeller, and the orientation and order does matter (I will include a picture for which order they go in below).
Used a large socket or seal installer tool to press them in, you do not want to damage the seals so be careful.
Next we need to install the bearings.
First we will put one ball bearing over the threaded end of the driveshaft along with the spacer (This will require the press to get on, it is a snug fit, lube bearing with marine grease prior to pressing in)
We will then again use the press, along with proper size bearing installers to press the bearing, and driveshaft assembly into the pump (the long end of the shaft facing down through the pump).
Once the driveshaft/bearing assembly is in, we will fill the cavity with the spacer with yamaha’s EPNOC grease or equivalent (some builders will use a grease and gear oil mixture as well).
after epnoc has been filled in the cavity, we will then press on the final ball bearing (again, lube the bearing with marine grease prior to pressing onto the shaft).
We then finish the assembly of the pump by putting on the washer and nut, then tightening to 50.9 ft/lbs .
After this we apply the other 20g of the EPNOC Grease into the cap, lube the seal, and then reinstall the cap (apply loctite 572 or equivalent to the bolts and tighten).
We then put the whole assembly back on the vise for the impeller
Apply loctite 572 on the impeller threads (do no forget the washer under the impeller)
Then tighten the impeller counter clockwise
This needs to be tightened to 81.1 ft/lbs
After this we are done, and the pump is ready to reinstall 🙂
I will update this guide over time, and make it more detailed and add more pictures
If there is ever any questions, or you need a better explanation, don’t hesitate to ask
Thank You
Evolution
