Impeller Advice

[Bill D]

So, my port side engine has always had a slight cavitation when I first accelerate. When I pulled the pumps, I inspected the impeller and found the cavitation spot in the picture below. Any suggestions? Does the impeller need to be replaced?

 

[swatski]

It has got to be missing sealant inside the pump/tunnel. I would bet it is the transom plate sealant gap sucking air, almost impossible to see until you pull it off, unfortunately. But that's just a guess.

I bet @WFO Performance would know! He has just blueprinted a @erj1452002 pump - work of art.

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[ISLANDRACING]

The leading edges of that impeller are SEVERELY beat up. That alone could cause cavitation. Also some mistake cavitation for an unbalanced impeller issue. While the pump is out, check for missing silicone in the tunnel area.

 

[tdonoughue]

I agree with @ISLANDRACING , of course. The nature of cavitation is that it is created at the edge (or before that in the flow path). The results of it appear where you indicate (where the bubbles pop). So, to answer your question, yes, I think you want to replace that impeller.

 

[Bill D]

Thanks for the replies. So my next question... Can the impeller blades be filed/ground/sanded down to remove the rough spots? I'm going to be looking into replacement impellers since it's probably time, but I would like to save these if possible.

I'll snap some better pictures tonight with my real camera. I was trying to zoom in on that little spot with the iPhone and it blurred things out a bit.

 

[Ronnie]

Check out impros.com in scal, I think they refurbish / rebuild impellers for $75 per plus shipping. I have heard that sbt (small block technologies) will send you refurbished impellers immediately if you send in cores for exchange purposes.

 

[swatski]

Thanks for the replies. So my next question... Can the impeller blades be filed/ground/sanded down to remove the rough spots? I'm going to be looking into replacement impellers since it's probably time, but I would like to save these if possible.

I'll snap some better pictures tonight with my real camera. I was trying to zoom in on that little spot with the iPhone and it blurred things out a bit.

Here is my advice: get new OEM impellers for $155 a piece, don't even think about it. You will thank me later.
PM me if you would like to chat. Yes, I do have strong opinions about this.
Here is the best source I ever found, if you call them (Amy) they may give you a partial shipping refund based on actual cost.
http://shop.powersportsparts4less.com/fiche_section_detail.asp?section=6386850&category=Boats&make=YAMAHA&year=2011&fveh=243076
#24 are the impellers.

If you do decide to refurbish, IMO you will be much better served by Skat, Glen is the man there.

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[Bill D]

get new OEM impellers for $155 a piece --

That's what i was afraid I would hear. Although, $155 a piece isn't terrible... I was thinking more like $300, which may be some of the aftermarket ones I have seen people purchase. I have to admit, I have been really curious what brand new impellers would do for my performance. I usually run about 48-49 mph. I guess it's a good thing I bought the impeller tool from Island Racing last time. Now I have an excuse to use it.

 

[swatski]

That's what i was afraid I would hear. Although, $155 a piece isn't terrible... I was thinking more like $300, which may be some of the aftermarket ones I have seen people purchase. I have to admit, I have been really curious what brand new impellers would do for my performance. I usually run about 48-49 mph. I guess it's a good thing I bought the impeller tool from Island Racing last time. Now I have an excuse to use it.

I think Solas have a merit in MR-1 boats, based on what I have read. I have no first hand experience but Solas even look like just a better version of OEM for the MR-1 pump. With the 1.8, the impeller design is radically different. I have a lot of first hand experience with those and feel very strongly that the 1.8 OEM impeller design is the best, especially for low end and cavitation issues. Longest blades, too. Not the smoothest running, but the best overall performers.

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[KXCam22]

Based on the pics, if it was my impeller I would clean up the edge with a file and fill the cavitation erosion spot with some jb weld. The get inside and fill any gaps and smooth out the tunnel with some 3m 5200. You can always buy impellers later if you are not completely happy. Cam.

 

[Bill D]

I took some more detailed pictures of the leading edge of the impellers. Looking more carefully, there are multiple cavitation marks on the port impeller. The spot I tried to picture earlier is by far the worst, but in better light, there are more spots. Let me know if you guys think these pictures confirm the "need a new impeller" diagnosis.

 

[swatski]

I took some more detailed pictures of the leading edge of the impellers. Looking more carefully, there are multiple cavitation marks on the port impeller. The spot I tried to picture earlier is by far the worst, but in better light, there are more spots. Let me know if you guys think these pictures confirm the "need a new impeller" diagnosis.

Doesn't look terrible, but it does look like some cavitation pits. I would pull the transom plate, I bet there is a gap between the plate and the transom and even a small gap would explain your findings. Just don't loose the little dowels between pump segments or strip any of those long bolts, I always worry about that (but never had a problem, yet).

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[Bill D]

I caught that when I pulled the pumps this time. I didn't know that those pins came out. They're only $1.25 from the link you provided earlier. I'm going to order some when I order the new impeller. Just in case.

I don't like the cavitation spots, so I'll likely order a new impeller for the port side. I also want to experiment with trying to clean up some of those burrs. I hate that there are two different impellers. Knowing my luck, the starboard pump will be the next to suck something up. Lol

 

[swatski]

Found it for you, finally.
This is for a ski, so a little different, and from greenhulk (I don't like anymore) but relevant:
http://www.greenhulk.net/forums/showthread.php?t=117375&highlight=transom+plate

Just the FIRST post, shows you how the factory left a gap! and use the 5200 -- this is permanent, I can't think of any reason you would want to be pulling that part up again.

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[Bill D]

I'll pull that apart and check it out. Since I've had the boat, I've done minimal investigating around the pumps. I pulled the pump after I got the boat just to make sure I knew how to do it. Then last year I pulled it apart and opened the cone for fear of rusty bearings. Seems logical that I should do a little more unbolting this year.

Thanks @swatski!

 

[dan144k]

@Bill D
Also consider that in an emergency to save a weekend or a trip, either impeller will most like work on either side. You may just not have optimal performance, but the boat will still go.

I know because I used starboard impeller on my port side, yamaha stock impeller, when my solas impeller blew up. Worked great for everything, except had too much cavitation for surfing with ballast.

 

[ISLANDRACING]

I also want to experiment with trying to clean up some of those burrs.

Yes the edges can be "filed" ... but what about balancing after you remove metal from the blades.

 

[Bill D]

Yes the edges can be "filed" ... but what about balancing after you remove metal from the blades.

That is where things get outside of my abilities. (And beyond my desire) I ordered a replacement OEM port impeller last night. I also ordered 4 of those little dowel pins to keep on the boat in case I ever lose one. Total cost was around $180, but I'll call Amy and see if she'll give me a break on shipping.

I'll take some pictures of the intake and transom plate area for feedback. Priority #1 now is to figure out where the cavitation was coming from so I don't ruin my new screw.

I really appreciate all the input given so far.

 

[Bill D]

While waiting for my new impeller to arrive, I decided to go ahead and get the old one off of the shaft. I used the Drive Shaft Holder that I purchased from Island Racing months ago and what I have dubbed the "Swatski wrench" which I was able to scoop up on Amazon this week. I put the shaft holder in a vice and it came off relatively easy. Especially considering it had been on there for 5 years and over 300 hours. I didn't need a cheater pipe or any lubricant.

 

[Seadeals]

Adding to this post: I finally experienced sustained cavitation after ingesting some debris. I pulled the plug and only found reminants of a leaf. After three reverse moves and nothing foreign left, it still cavitated until fully on plane (7500-8000rpm).

I suspect it chewed up a stick. You can see the damage strangely on the trailing edge. It must have been caught in the fixed vanes aft and chopped by this blade.

With another boat day approaching, I figured I would experiment on it. With a little mallet work and a tiny bit of filing, it did eliminate the cavitation. I will definitely refurb this winter; just undecided if I should get a spare for our upcoming boat vacation.