Impeller Bearings

[Ernie]

Hey Guys I pulled out the impeller shafts today because I do get cavitation and wanted to check the impellers and housings. It looks like the Starboard side impeller housing has some wear so Im just going to replace both sides with new impellers and housings. The boat is 10 years old with about 160 hours on it.

I pulled off the bearing caps and there is no sign of water and there is grease in the cap but not much on the bearings. Here are a couple of pics so you can see what I mean. I may just take it to a PWC place and have them pull off the bearings to check and repack them. This is the port side but the starboard bearings look the same.

What do you guys think?

 

[Bruce]

I think you should either leave the bearings alone or change them.

Here is my thread on changing them with helpful contributions from others https://jetboaters.net/threads/chan...-and-switching-to-oil-bath-lubrication.10155/

 

[Ernie]

Wow Bruce thats crazy but props to you for posting and going through that. I think I will just take the shafts and have them checked out.

 

[Ernie]

So I pulled off the impellers and the front seals look good no leaking but because of the age and hours I think I will still have them checked out and repacked.

 

[ISLANDRACING]

there is grease in the cap but not much on the bearings.

Typical of the OEM grease. Use the LIQUID PUMP GREASE !!!

 

[Ernie]

Typical of the OEM grease. Use the LIQUID PUMP GREASE !!!

Just how would someone add this grease? Should everything be cleaned out first and add new seals?

 

[Bruce]

You can not get to the more forward of the two bearing back there without removing the bearings from the housing. At that point you might as well replace them.

Then you can either use Island Racing's magical slurry or an oil bath. I decided to use an oil bath but if I had not I would have used the Island Racing product.

 

[Ernie]

Hey Guys Im trying to put the shafts back in with new impeller SS housings. It seems the new impellers are going to rub inside the new housings is this normal at first or is there a trick to getting them lined up so they dont rub? Should I just put everything together and then install it all in one piece instead of a section at a time?


Thanks for any help.

 

[Bruce]

Where did you get the SS (stainless steel?) housings?

There is a spec for a gap measured by a feeler gauge between the impeller and the housing. That spec is in the owners manual. There should be a gap.

I reassemble the pump with RTV between the sections and moly grease on the spline of the shaft then slide the entire assembly into place.

 

[KXCam22]

Can you explain further. You have new SS impellers AND SS housings? Cam.

 

[Ernie]

No Im sorry to confuse its all stock from Yamaha. I meant aluminum .

 

[Bruce]

The impeller clearance specs are in this thread https://jetboaters.net/threads/impeller-gap-010-good-or-bad.9484/ . The only way I know to measure the clearance is using a feeler gauge with everything reassumed.

 

[Bruce]

No Im sorry to confuse its all stock from Yamaha. I meant aluminum .

Funnily enough the Yamaha housings are aluminum with a stainless liner.

So you have new impellers and housings with old bearings? I would change the bearings if you are going to replace everything else. Getting the impellers off is the hardest part.

Do the impellers slip into the housing?

 

[Ernie]

Put it all together first and it all seems ok. Im at 0.30mm or .012 less than spec but it clears fine. I talked to a local PWC shop about the bearings and he said they pull the caps off every year and check for water when they winterize . There was no water in mine so per his advice I cleaned out the old grease as best as I could and worked new grease down into the bearings and refilled the caps and put on new O-rings. I got the grease from that Redi-driver place and it looks and feels like the same stuff. I will pop the caps back off in the fall to see how it looks.