Refurbing a Jet Ski/PWC impeller?

[tjs]

Anyone done this. Please do not say just to send it out to the “pros”. The only concern I have is that the impeller blades are on different planes. I already made a mandrel (old impeller shaft). The factory impellers are stainless but are magnetic, I will be using 312 filler rod and tig the blades up and then when I think the build up is high enough I will turn it back down to get the impeller to housing clearance I need. I have posted this on a PWC board and most think that this is rocket science and comment and have no idea what they are talking about and only regurgitate on what they read somewhere else on the interwebs. To me this just sounds like machining 101. You can see in the pic of the failure with 38 hours on this machine. I have a new shaft and bearing kit. Was able to clean up the seal area of the housing too. The impeller walked forward in pushed on the crank thrust bearing and now I have metal in my oil. So the engine is coming out of this thing. Bad design.
Thanks.
T.J.

[gambler]

you can do it! but take pics and let us follow along. sounds interesting. oh and have you figured out a way to prevent it from happening again?

[EddyCurr]

The factory impellers are stainless, but are magnetic. I will be
using 312 filler rod and tig the blades up

Magnetic properties for the impeller? This may suggest it is from
the 400 series or something fancier. 17-4 ?

Is 312 filler rod, one of the austenitic grades, a compatible choice?

.

[tjs]

Magnetic properties for the impeller? This may suggest it is from
the 400 series or something fancier. 17-4 ?

Is 312 filler rod, one of the austenitic grades, a compatible choice?

.

These impellers are made in japan. Not sure what they use and call it stainless. I was going to use 309 but it was suggested I use 312.

[EddyCurr]

Wonder whether the material can be narrowed down?
Metalurgical analysis on some scraps would get help get
there, but I suppose this is a cost.

For a lark, let's speculate that the impeller is 17-4PH
(precipitation hardening). Lincoln has this to say about
welding ...

Stainless Steels Welding Guide
By Lincoln Welding
Page 11 of 40 (pg 9 of printed doc)

If maximum strength is required in martensitic and semiaustenitic
precipitation hardening stainless steels, matching or nearly matching
filler metal should be used and the component, before welding, should
be in the annealed or solution annealed condition. Often, Type 630
filler metal, which is nearly identical with 17-4 base metal, is used for
martensitic and semi-austenitic PH stainlesses. After welding, a
complete solution heat treatment plus an aging treatment is preferred.
If the post weld solution treatment is not feasible ... (continues in doc)

.

[JoeLee]

I've done many of those impellers. That design is easier than some. The housings usually get the worst of the damage when you suck gravel through them. They do operate on close tolerances between the blade edge and the housing, but you can follow the existing edge. It should be an easy fix.
Do worry about the alloy too much. Those impellers are all garbage stainless and fall somewhere in the 400 series so any SS rod will work. The only difference would be color and I doubt your concerned about that. I don't think balance would be an issue either as long as you don't pile blobs of weld on the flats.

These are easier to fix............

JL....................

[JoeLee]

[JoeLee]

Wonder whether the material can be narrowed down?
Metalurgical analysis on some scraps would get help get
there, but I suppose this is a cost.

For a lark, let's speculate that the impeller is 17-4PH
(precipitation hardening). Lincoln has this to say about
welding ...

Stainless Steels Welding Guide
By Lincoln Welding
Page 11 of 40 (pg 9 of printed doc)

If maximum strength is required in martensitic and semiaustenitic
precipitation hardening stainless steels, matching or nearly matching
filler metal should be used and the component, before welding, should
be in the annealed or solution annealed condition. Often, Type 630
filler metal, which is nearly identical with 17-4 base metal, is used for
martensitic and semi-austenitic PH stainlesses. After welding, a
complete solution heat treatment plus an aging treatment is preferred.
If the post weld solution treatment is not feasible ... (continues in doc)

.

You don't need to be any where near that fussy with alloy TIG rod for prop repair. The Lincoln welding guide is for structural welding not chip filling on a propeller. The only thing I use the 17-4PH for is the real expensive SS props because the color blend is usually closer.
I've never seen a SS prop that was advertised as anything other than stainless steel. Basically SS props are the pot metal of stainless.
You can't classify them as any 400 series because the percentages of alloys vary so much

JL......................

[gambler]

joe lee, when can you fix my prop?

[JoeLee]

Any time you want..............

JL...............

[tjs]

Thanks for the comments and suggestions everybody. I appreciate it. Yes I agree that so called "stainless" material from overseas is not the greatest stuff. Hence I will use the 312 filler. I will post pics of the process when I get to it and hopefully this part of the issue will be a save.
Thanks again.
T.J.

[boslab]

If nothing else it will be a good bead running exercise, distortion probably won't be an issue as it's unrestrained, besides the flap wheel is going to get it, not a bad little bench job
Nice repair from joelee, looked really good
It occurred to me that on a leading edge that a harder alloy might be good, but I'm probably wrong, cracking may occur
Mark

[JoeLee]

The only thing you may eventually noticing with using the 300 series rod is that in time and depending on the iron content of the SS prop you may notice that the weld area will develop some surface rust where the filler meets the base metal. This is due to the iron boiling to the surface during the welding process. I believe it called carbide precipitation.
The 17-4 PH rod will actually reduce some of that as I think it adds a little more chromium to the weld area, you don't have to get that scientific with it!!
It's just a prop......... it's only going to get dinged up again. It's more important that it's properly profiled and balanced.

JL.................

[tjs]

I never updated this. I have been to busy out on my jetski after I fixed it. Here is how I did it.
I cut out the wear ring very carefully and found a company that sells replacements. The PWC crowd thinks this is voo doo and cannot be done.


Then I pressed the new one in.


Note new shaft and bearings and seals.

[tjs]

I then TIG welded it back up using 312 filler.


I cobbled up a tool post grinder out of junk. I used a foredom shaft grinder. And this is how I got it to where I wanted it.


Then did a final polish on the edges.


Nice finish.