Cavitation?

[Budman]

I bought a 2007 SX230 HO in July of 2019, so I`m new to the boating world. I had my boat out yesterday and we were up and down the lake pulling the grandkids on the tube for a couple of hours. We stopped a couple of times so that everyone could get in the water to cool down during this time and the boat ran great. We ended up going up into a little cove to have some lunch and when we headed back out to the main part of the lake to do some more tubing the starboard engine would rev up, but there did not seem to be any force from that side. I ended up looking to see if the cleanout plug popped out, but it was in place. I ended up pulling the plug to see if there was something wrapped around the pump shaft and I found a piece of weed stuck in there. I got the piece of weed pulled out and replaced the plug, but it still did not have any force, so we ended up loading the boat up and headed home. I ended up getting on the forum to see what I could find out as to what the problem may be and I see a lot of threads talking about cavitation. They are saying that it does not take much to get into the pump to cause cavitation, so my question is is how small of a piece of whatever can cause cavitation if it gets stuck in the pump? I looked back through the outlet end of the pump when I got home and I can see what looks like a little piece of a twig about 3 inches long and about an 1/8 of an inch in diameter back in by the impellers. Does anyone think that this could be causing the cavitation? if not, any ideas?
This is the only thing I could see.

 

[Babin Farms]

First off Welcome!!!

Any amount of debris can cause cavitation. I experience it most often in a situation like you, after sitting a while or floating and then fire the engines and get going. Did you have vibrations from one side or the other?? Another way to clear an obstruction is the reverse maneuver which is about a 50/50 shot at working most times.

https://jetboaters.net/threads/easy-way-to-clean-debris-out-of-your-jet-pump-without-pulling-plugs-or-going-in-the-water.16/

 

[Budman]

First off Welcome!!!

Any amount of debris can cause cavitation. I experience it most often in a situation like you, after sitting a while or floating and then fire the engines and get going. Did you have vibrations from one side or the other?? Another way to clear an obstruction is the reverse maneuver which is about a 50/50 shot at working most times.

https://jetboaters.net/threads/easy-way-to-clean-debris-out-of-your-jet-pump-without-pulling-plugs-or-going-in-the-water.16/

I did not not notice any vibrations. When I throttled up it just did not sound right, so I throttled back down right away. I ended up throttling up port engine and it sounded fine and had lots of thrust. I then throttled up the starboard side and the wash coming out of the pump sounded funny, and there was not much thrust. I did try the reverse maneuver a couple of times thinking there may be something in the pump, but it still did not have much thrust, so that is when I decided to pack it in for the day.

 

[Scottintexas]

I looked back through the outlet end of the pump when I got home and I can see what looks like a little piece of a twig about 3 inches long and about an 1/8 of an inch in diameter back in by the impellers. Does anyone think that this could be causing the cavitation? if not, any ideas?
This is the only thing I could see.

There is no question the "twig" in your pump is causing problems,

Pull the pumps, it should easy and every jet boater should be versed in doing them, then go back to the water, chances are you won't have any more problems,

Be sure to look at the link in my signature line below for known issues with your model boat, this along with our FAQ at the top of the page has many great pieces of advice to help you,



.

 

[Budman]

Thank you so much Babin Farms and Scottintexas for your inputs and advice. My wife asked me sunday evening when we got back home as to where I was going to take the boat to have it looked at, and I told her that I was not taking it anywhere, I was going to get on the forum to find out what the problem was. This site is so informative, I don`t know why anyone would take there boat to a shop. Not real sure on how much longer we`ll be keeping this boat because it gets pretty crowded with 6 adults and 5 grandkids at times, so the wife has been talking pontoon, but while I still have it, I`ll still be on here learning everything I can.

 

[HangOutdoors]

@Budman No shame in someone taking a boat to a mechanic or dealer for work and service. Some people are just not mechanically inclined and are intimidated by working on their boat. Which is Ok. For those that don't mind working on their own watercraft this site is invaluable when it comes to help, info and ideas!

 

[sunbyrned]

Agreed with all of the above. I have found though that the reverse/forward/reverse, etc. maneuver kicks that stuff out most every time. Pulling the pump is one of the first things I learned how to do on my boat. (Pulled out a 3 inch twig. Ha!) Here’s the tutorial I watched to do it. If you take it to the shop, you may not get your boat back this summer. You can knock this out in 30 minutes or less.

 

[Budman]

You are right HangOutdoors. This site is invaluable for help and ideas. You are also correct in there is no shame for someone taking a boat to a mechanic if they are not mechanically inclined, or intimidated by working on there boat. I guess by turning wrenches on things from bicycles to bulldozers about my whole life and not being afraid to tear into things, so I think that is just part of life and I guess I forget of those that are intimidated by doing it.

 

[Budman]

Thanks for the vid Sunbyrned. It looks easier to do than what I figured it would be. I know what I`ll be doing when I get home from work today.

 

[HangOutdoors]

As a caveat, there are members here who don't mind helping someone local. I have already installed Trim Tabs, twice, and Cobra Jet Steering as well on Forum members boats since they didn't have the tools and were nervous. The sudden look of panic and fear when I bust out the drill and get ready to drill their hulls is priceless. I enjoy working on boats.

 

[sunbyrned]

In addition to learning how to spit that stuff out, one tip I’ll give to try to avoid sucking the stuff up is to turn your engines off if you are ever idling, such as stopping to pull up bumpers or something.

 

[Budman]

I learned that lesson the first time we tried our hand at tubing sunbyrned. After sucking the tow rope up, I shut the engines down any time I stop. I would guess that when I sucked the stick up in was when I started the boat back up after we ate lunch that day because we were only setting in about 4 to 41/2 of water. Another lesson learned, never stop and eat lunch in 4 feet of water.

 

[sunbyrned]

This makes me wonder if when anchored, would it be beneficial to put the levers in reverse to shut the gate. Wonder if this would help prevent debris collecting there. In addition, I have a new place to launch my boat, but unfortunately it is full of sticks and stuff and I always have to spit them out when I get to the main water. I’m thinking of designing a deflector to push debris away while in reverse. I think that’s when I’m picking the stuff up.

 

[Budman]

I was anchored with the bow of the boat facing shore, so I had to back away to leave. I did notice that when backing up, the water out in front of the boat was all muddy and churned up. If you design a deflector, keep me posted on what you come up with. I was thinking of doing the same, so I`ll keep you posted if I would come up with something.

 

[Budman]

Thanks to all for all of the input for my dilemma. Pulled pump last night when I got home from work to find this little piece of wood stuck to the impeller just like in the video sunbyrned sent me, who would have thunk something that small would cause such a problem. Now I know that it does not take much to cause cavitation.

 

[sunbyrned]

Thanks to all for all of the input for my dilemma. Pulled pump last night when I got home from work to find this little piece of wood stuck to the impeller just like in the video sunbyrned sent me, who would have thunk something that small would cause such a problem. Now I know that it does not take much to cause cavitation.View attachment 154512

Nice!

 

[Scottintexas]

it doesn't take much to cause cavitation but luckily it doesn't take much to fix it either,

as far as size goes, that thing is a redwood, something as small as a toothpick lodged between the blade and the wear ring can cause issues, luckily most of the small stuff gets chopped up and spit out


now consider that second bilge pump w/high water alarm,

.

 

[russbly]

Would cavitation cause the RPM's to bounce? My starboard side TACH bounces, I don't know if that makes sense. It eventually seems to catch and then we are gone.

Or would the bouncing be engine related?

Thanks,

 

[okula225]

Would cavitation cause the RPM's to bounce? My starboard side TACH bounces, I don't know if that makes sense. It eventually seems to catch and then we are gone.

Or would the bouncing be engine related?

Thanks,

Did you happen figure this out? Mine is experiencing the same issues currently.

 

[HangOutdoors]

Sounds like heavy cavitation.