550 takes on water but can't find where

I live on a small lake and one of the residents always sees us riding year round. Last weekend he asked me to take a look at his ski to figure out where water is coming in. I asked him a few questions and here is what he told me:

Its a JS550 that leaks water whenever the ski is running and the throttle is open. He replaced all of the hoses but doesn't know where the water is coming in from. He said he can't see where water is coming in. When the ski is sitting in the water, it does not leak. Only when ski is running and throttle is open.

Im thinking maybe the waterbox or waterbox hose on each end might be cracked/broken?

Any other suggestions? The water is 46 degrees so I would like to have a list of things to check before getting in and trying to troubleshoot it. Thanks for the help
 

Big Kahuna

Administrator
Location
Tuscaloosa, AL
Check the stock bilge. The hose comes up by the electical box to a plastic fitting and then down to the strainer. If the hose and fitting fall over and lay in the bilge it will let water into the engine bay.
 
Location
Delaware
Can't you try back flushing first to see where it's leaking? Easier than putting in the water and running with hood off up against a dock, etc.

Otherwise I'd just check all water connections for tightness and then if they leak.

Could have a bad exhaust hose or coupler somewhere but I'd suspect he'd have more issues than just water intake.

Maybe he didn't winterize and water froze and cracked something.
 
could also be thru hull water supply line.aluminum tube with plastic jacket corrodes and breaks or leaks.
check all your lines,exhaust hoses etc..
not too much on those boats
 
I will for sure check the hoses, connections, bilge, etc but figured I would ask if anyone else had a similar issue before I went to go look at it. Boats are simple and I've had a couple but seems like its a mystery as to where the water is coming in. He's had a couple other guys look at it.
 
Like Kahuna said make sure the bilge hose loop rises above the level of the lake water. Otherwise it will siphon INTO your engine compartment.
 
the bilge would not backflow with motor running as venturi at pump nozzle sees low pressure and would vacuum water out..
it would do it with motor stopped which is not what op indicates.
op,also check that pump nozzle has the needed shroud over bilge outlet and if nozzle has been bored that extention tube is still in there.
 
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