Islandia cavitates when launched- just fine after half hour...

[huskercheesewi]

First off- bought my Islandia this spring, and I have to say its been the best purchase we have made as a family! It has truly been a summer to remember as a family...

Okay so lately, when I launch the boat and idle out past the wake zone and put it under power it cavitates. I get 6k+ RPMs, but no power. I have been thinking maybe I just sucked up some weeds so I kill it and drift a while- then jump in to clear any debris and there is nothing on the grate.

I fire it up after we all swim for a while and take off like a rocket. This has happened the last 3 times now, all on different lakes -- cavitation at first and then fine sitting in the water for a while.

Any ideas?

Thanks - you guys are awesome! Happy boating!!

Nate

 

[Dr Honda]

I've been thinking about your problem... and it just doesn't make sense. I'm thinking you are getting something over the grate in the no-wake zone... and when you shut off the engine, to check it... it just falls off before you get to it.

Next time it happens... kill the engine, and rock the boat a little... then try to go again.

The thing is... the things that lead to cavitation don't just go away.

 

[huskercheesewi]

Well that's definitely encouraging, thanks for the feedback. I was thinking maybe there is some type of seal that once it was wet that is somehow reduce the amount of air that would be allowed through the pump.

So just so that I understand, if it is an impeller that needs to be changed or the ring is bad etc.- then it will always cavitate... therefore if it cavities intermittently then it is some type of blockage?

 

[Dr Honda]

Yes... generally... if you have cavitation from high clearance in the ring... or a messed up impeller... you will normally always feel it. It will be worse at high loads, and low speed.


Since the Merc boats have an enclosed pump housing... the only seal that could leak, would be from the gearbox. And, if that was the case... you would leak out the gear lube... but you still probably wouldn't draw air. Speaking of that... have you checked the gear box oil? (just to make sure it's clean)

On the Rotax boats... there are a bunch of places that air could leak in at. (Carbon seal, Boot, Hull fitting, around the ride shoe, base of the pump) That's why we separate the 2 power systems.



BUT.... with that said... I'm going to look over the parts diagram to see if there is anywhere that could draw air.

 

[185utopia210]

When we get cavitation, and its usually from going slow in a weedy zone; I just reverse it for a couple seconds, then shut it off, wait 5 sec and its always good.