cavitation at 67-6800 RPM, worse w/heavier the load

[adamsrotors]

you may have seen my issue post, after ripping off my rudder in some shallow water...
most of it has been fixed/repaired, yet I'm still experiencing some cavitation at higher RPM's that prohibits me from coming to full plane with a full boat.

this past sunday I was out with 6 people total and it was really struggling.
there is a high/loud hum or whine at 67-6800 PM and has a hard time getting out of the hole and up to speed.
I feather the throttle a bit and fight thru it, and it happens...eventually. we take off an all is well.

now days before, it acts fine...me and a buddy out only for testing purposes after the initial tear down, stick removal, and new cobra jet fangs & planning surface were add. almost unnoticeable really.
then yesterday after the issue with 6 people, me and 2 others (3 total this time) little issue but works fine, enough...really no struggle at all, only the sound for a quick few seconds, as it comes to plane.

clearly it's struggling with more weight on board.
...it's an impeller issue, right?

click HERE fo a video of the impeller after initially removing it to get the stick out.
does this look right? is there a uniform bend I'm not noticing that shouldn't be there or something?

 

[anmut]

My first question is: Are we talking about 6 tweens or 6 adults. Six, 200lb adults is 1200lbs - that's some no bullspit weight. If you had an uneven bow/stern distribution I could see some slip and struggle from a single engine pump on a 19' boat.

 

[adamsrotors]

^ I get your question (3 grown men & 3 hot chicks) but it's not just that.
been out with them before and out with a full 7-8 passengers and no issue prior to the "bad day" we had.
and regardless, this sound is new.

 

[Scottintexas]

I wonder if the force of breaking the rudder (articulating keel ) dislodged the ride plate enough to loosen the sealant and now your sucking some air at higher loads.

When I had my cavitation issue it was because of loose or missing silicone in the housing area. I would have to feather it to get it up to speed otherwise I had loud sounds and vibrations. Some of my sealant was loose, it looked ok but wasn't sticking so you could pull it away with your fingers,

I would start by pulling the impeller, make sure it's clear of debris and look at all your silicone to make sure nothing obvious and go try it again at the lake, if it's still doing it I might silicone over every thing that wasn't flush and see if that helps.


.

 

[adamsrotors]

^ well I did pull the impeller...did you click link for video?
where am I looking for the silicone exactly? any photos would be a HUGE help.

 

[2kwik4u]

Here's my writeup on resealing the intake tract on my '17 AR190.

https://jetboaters.net/threads/hero-or-zero-resealed-my-jet-pump.17845/

Made just as much of a difference as the L13 did. Cost like $10 I think, and has lasted two years. I pulled a tube this weekend with 4 fullsized adults, and 4 kids under 10 in the boat with no cavitation issues.

 

[Scottintexas]

^ well I did pull the impeller...did you click link for video?

apologies, was confusing your issue with another member who just joined having impeller issues,

here's my post about my issues,

https://jetboaters.net/threads/cavitation-missing-sealant-in-pump-grate.884/

 

[adamsrotors]

so doing this AND a cone should be great, right?

I'm on it...thanks. I'll be doing this when my cone finally arrives.

 

[adamsrotors]

what's the best product to use here? you guys both used two different things?
I have time to order online, so lmk.

 

[2kwik4u]

so doing this AND a cone should be great, right?

I'm on it...thanks. I'll be doing this when my cone finally arrives.

I did the cone first.....and it helped....then I did the tunnel seal....and it helped. Neither were like "OMG what a huge change", but I can't cavitate my pump (that sounds dirtier than it probably should) without significant effort now. Have to apply all the throttle in a hard over turn at 30mph to get it to cavitate.

 

[2kwik4u]

what's the best product to use here? you guys both used two different things?
I have time to order online, so lmk.

My loctite is 2yrs old now, with just a few spots missing from original application. Picked it up at Home Depot i think.

General recommendation is the 3M 5200 sealant.

I don't think either will steer you wrong. Choose which you can get your hands on. Worst case it all falls out and you put another $10 of goop on it

 

[adamsrotors]

to be clear this is all done from under the boat thru the grate?

 

[adamsrotors]

completed the re-seal. no difference.
boat performs completly normal w/1-3 people. 4-5 it's struggling...6+ it's bad and almost never comes to plane.

 

[2kwik4u]

completed the re-seal. no difference.
boat performs completly normal w/1-3 people. 4-5 it's struggling...6+ it's bad and almost never comes to plane.

Next step is to make sure you have the proper clearance between the impeller and the wear ring. I think 0.030in is the spec, but you'll want to double check.

I'm getting close to out of ideas here.

My 190 can get on plane with 2 adults, 6 teenagers, and 3 coolers. It takes longer, but it'll get there.

 

[adamsrotors]

anybody take look at my impeller video? does that look normal?

 

[Peter simon]

I am not an expert, but after looking at the video i think it might be bent. Our lake, Lake Wylie in NC/SC has had the dam gates open the last few weekends and there has been a ton of debris. I went 1.5 years never even opening the cleanout and now I am surprised as how small of a branch/piece of wood causes the cavitation. Sometimes its not even caught between the impeller and the tube around it. I have noticed we are more likely to pick up debris when the front of the boat is loaded heavier.

 

[adamsrotors]

sending my impeller and wear ring in to impros after a nice long convo about it all...should be fixed up fairly quick and for fairly cheap too.

 

[ellj]

@adamsrotors was the issue wear ring or impeller?

 

[adamsrotors]

both...they replaced the ring and repaired the impeller. they're killer to work with too.