Cavitation possible due to SC rebuild, or unrelated???

[ligiman]

Good day everyone. I have read these forums a lot, but I am now a member and my first post.

I have a technical question regarding a supercharger rebuild on my 2009 SeaDoo 230 Wake (twin jets). I recently took it to a local SeaDoo shop for a new port side starter relay after intermittently not starting and decided to get the superchargers rebuilt as I was not sure if it ever had been done (bought it at 170 hours and took it in with 196 hours).

After getting the boat back from the dealer, I immediately noticed the port engine increasingly had higher RPMS than the starboard engine depending on throttle. It was about the same at idle, and would climb up to a 700 RPM difference as I throttled more. (I remember that one side was often slightly higher than the other previously but nothing major, and it fluctuated, so I attributed it to weight distribution due to passengers.) Then, about 30 minutes of driving later, the port side started cavitating at higher RPMs. I took it back to the dealership wondering if it was a coincidence or related to the supercharger rebuild. They told me that could not be related to the rebuild and then proceeded to diagnose.

They eventually told me the reason it was cavitating was that my port side impeller was bent at an edge and that I needed to replace both impellers so that they match for $1500 (the guy I bought it from put some aftermarket stainless steel impellers on it, so it was not OEM).

I didn't want to drop another $1500 as I researched and found that you can get impellers replaced for a LOT less, and i took it back to the guy I bought it from (he has a pontoon dealership and jet ski/boat rental business with full service shop). He saw no damage to the impeller (he said they still looked brand new and wondered if I had even driven it much...) He even switched the impellers, and cavitation stayed on the port side, therefore eliminating a bent impeller as the cavitation cause.

He suspects the drive shaft seal, and has that on order, so that is where we are at with it, but I wanted to reach out to all of the experts here and ask the following:

A) is there any possible way that a SC rebuild or the work involved with it can cause or lead to cavitation? If so, I don't know if I really want to take it back to the SeaDoo dealership, as I am not sure I trust them, as they did not correctly diagnose the problem AND apparently didn't even inspect the impellers correctly (they told me they needed to replace both since they didn't know the make of the impellers, but I learned that they are stamped so that they COULD know that...)

B) has anyone experienced anything similar or have any suggestions on what could be causing the cavitation. FYI, both places said the wear rings looked good, so its not that either.

Anyway, I wanted to get another opinion from an objective third party if there was any thing that could be done wrong or incorrectly during a SC rebuild could cause cavitation at high RPMs.

I look forward to everyone's infinite wisdom!

 

[JoeZ]

The supercharger rebuild in NO WAY could have caused the cavitation. However, it is possible that you were down on power and didn't notice the problem until the rebuild brought your power levels up high enough to increase the symptoms.

$1500 for new impellers is crazy...we sell them for significantly less and the labor shouldn't be but a couple hours max.

I'd more trust the pontoon dealer, but always hard to know for sure without looking at it. Good luck!!

 

[ligiman]

JoeZ,

Thanks for that reply. That is great to know; I really didn't want to be forced to go back there and argue he said/he said on a non-bent impeller. I will check your shop out for any future DIY projects I can handle.

Thanks again!

 

[Joe Starbuck]

A properly executed SC rebuild, on an engine that was already producing good power, will not cause cavitation, as JoeZ said. However, if the cavitation turns out to be caused by the shaft seal, and that shaft seal is right below that SC, and they dropped that SC on that shaft seal, anything could happen.

 

[POPPS]

The guys are right,,,the SC has nothing to do with the cavitation,,,except that now that motor is working 100. % and any faults will now show,,.and 1500 to replace 2 props,,,is very heavyily insane,,,post a pic if the prop,,,impros can no doubt repair it like new,

 

[turbosl2]

Since I am in the process of rebuilding my chargers and own a challenger 230 with twins I am going with the diagnosis that the carbon seal was damaged mistakenly. To pull these chargers out I had to remove the exhaust on each motor and push them back 4”. Also as mentioned above the charger is right above the carbon seal and maybe as the tech loosened the last bolt it fell on it. It’s possible but it also has a protective boot on top of it. So the extra pump power (assuming you had a damaged charger impeller or slipping clutch) is just as possible. I just ordered upgraded +5mm carbon seal kits from green hulk. I have not installed them yet

 

[ligiman]

Thanks everyone for their input; it all makes sense that the 100% power is just letting existing faults be more apparent...

POPPS, interestingly (or suspiciously?), I suggested to the seadoo dealer early on in the discussion that we just repair the portside impeller, and she gave me a line that you can't repair impellers because then there is more gap between the impeller and the wear ring, and so you just need to replace it. I think she was dead set on getting some more money from me

turbosl2, that is also helpful to know as you have a similar boat, and what could have possibly happened. I think trying to prove that to the seadoo dealer AND even wanting them to work on it again is a losing proposition so I think I will just let the dealer I trust and who also suspects the seal take care of that and just cut my losses. Good luck with your SC rebuild; I hear it is pretty complicated, precision work.

I tell you, finding a mechanic you can trust is as valuable as a good wife...I have the good wife, and I'm thinking/hoping I found the trusty mechanic with the pontoon dealer...

Happy boating this weekend to everyone!

 

[turbosl2]

Thanks everyone for their input; it all makes sense that the 100% power is just letting existing faults be more apparent...

POPPS, interestingly (or suspiciously?), I suggested to the seadoo dealer early on in the discussion that we just repair the portside impeller, and she gave me a line that you can't repair impellers because then there is more gap between the impeller and the wear ring, and so you just need to replace it. I think she was dead set on getting some more money from me

turbosl2, that is also helpful to know as you have a similar boat, and what could have possibly happened. I think trying to prove that to the seadoo dealer AND even wanting them to work on it again is a losing proposition so I think I will just let the dealer I trust and who also suspects the seal take care of that and just cut my losses. Good luck with your SC rebuild; I hear it is pretty complicated, precision work.

I tell you, finding a mechanic you can trust is as valuable as a good wife...I have the good wife, and I'm thinking/hoping I found the trusty mechanic with the pontoon dealer...

Happy boating this weekend to everyone!

Haha your right on with that! I do all the work myself and it’s a PITA but at least it gets done right. PWC muscle has been awesome with the rebuilds. I sent them to them because I needed new impellors on the chargers and didn’t have 2 used ones. Both had touchdown.
Also impellors can be fixed and pitched. There is a company on the forum that does them. Glen perry in CA if I recall. Google it. I think this is the company.
Contact Us
He did my PWC impellor and repitched as well for my needs. He can repair any damage and balance them. He’s like a god for impellors on jet pumps. The gap the dealer is talking about is just a $40 wear ring. You should not have to throw any pump impeller away.

 

[turbosl2]

Services

 

[MacSeaDoo]

If you can, crawl under and snap some photos of the impeller as if your wear ring and impeller are damaged/worn, any further amount of troubleshooting is a waste of time.

Replacing the SC has nothing to do with the carbon seal and I can't see how you could damage it unless intentional.

What can damage it pretty quick is running the engines out of the water for any extended period beyond idle. When I say extended, I mean anything beyond 1 minute at idle. If you run up the rpms you can lower that damage time to under 30 seconds.

If the carbon seal leaks water in, it will leak air through the seal when the pump creates a vacuum on the feed side. Air can compress and cause cavitation.

A go pro is a great diagnostic tool here. I have a flat panel LCD flashlight and I just drop it down looking at the carbon seal a video a run. Pretty easy to see it leaking on video.

 

[ligiman]

MacSeaDoo,

thanks for the info. The impeller and wear ring have been inspected and they are fine, but your other advice is a great excuse to buy a GoPro!

FYI, the only time I run the engines out of water is to very quickly crank it and rev it to blow any water out (2-3 seconds maybe?). Is that a good or bad practice?

Thanks.

 

[MacSeaDoo]

Personally reving the engine anything beyond idle is unnecessary and just accelerate wear on the carbon seal.

The only thing you might be doing is reducing the amount of water in the exhaust can. The can is aluminum and you will never completely empty it without running it hard for a much longer period then would be practicable.

When I pull my Speedster out, I flush it at idle until I get cold water from the Intercooler vent line, then shut it down.