exhaust resonator failure.

[2001GTXseadooRFI]

So last weekend the exhaust resonator on my ski failed and I took on water and sunk. got the ski running again, flushed everything out as I should. Later on I found out why the ski took on water. So I know that it took on water because the seam failure and an additional hole the size of a quater in the elbow of the resonator formed. But my question is why? Is this something that can typically happen with an older machine? What could have caused this? i would think this was a perfect reason as why the exhaust should not be made of plastic. the spark plugs loaded up coming off the dock. So I stopped in shallow water area, changed the plugs. Got it up and running again. Then I started making a few quick passes to clear it out. I heard a pop, the engine died. exhaust smoke started comming up from the hood. I couldnt keep it running after that. I then heard water rushing in by the battery area and the rest was history. The best I can figure is that the exhaust system might have filled up with unburnt fuel/fumes as the ski was only running on one cylinder for a few minutes. Then when I got it going with fresh plugs and the hot exhaust mixed with the unburnt fuel, boom blown out exhaust. Any thoughts?

 

[Dr Honda]

it melted because it got hot. OK... I know that sounds obvious... but it shouldn't be hot. The cooling water for that is directly controlled by the regulator on top of the waterbox.

SO......

1) The feed tube to the reg is clogged
2) The reg has gone bad
3) The fitting on the pipe, that is fed by the reg is clogged. (It's a small orifice, and it can plug up quickly)

 

[fractus]

Looks very simular to mine. Is the $.25 hole on the elbow before it exits the transom? Did on mine.Had it happen to my 98 GTX-RFI. Had some weeds in the grate which I cleaned out. Made a 3mile cruise at about 40. Stopped to get some water, started taking on water fast. Tried to start it to make it to shore, would run a minute, actually not more than idle. I just happen to be at a park on the river; most of the river has trees/cliffs on both side w/o beaches. I didn't hit anything ski was running fine...Beached it the best I could in about 10" of water found and empty bleach bottle to prop up the back and bailed it out with a cup from the trunk. I didn't want to leave it overnight as it was getting dark and the campers I'm sure would have cannibalized it by midnight; although none would offer help. Called a friend that has a flatbed wrecker. Put it on a pallet and winched it. I was about 7 miles down river from home.
What I think happened is that some weed material got into the water injection into the exhaust and the plastic overheated and melted.
Check your water regulator, I believe there is a sticky on that...Sorry man for your loss.

 

[fractus]

Hey Doc.. I took me a while to type all this, seemed you beat me to it.:boxing_smiley:

 

[2001GTXseadooRFI]

Ok, good info. I can deffinately see what your saying. I'll give everything a good check and inspection before I re-install the new resonator. I have a few days before it arrives anyway. I'm not by the machine now. But when you say regulator on the water box. Are you rferring to the rave valve that's on the water box or is there something else? And yes the small .25 cent hole is in the bend/elbow leading to the exhaust port on the hull.

 

[Dr Honda]

.... But when you say regulator on the water box. Are you rferring to the rave valve that's on the water box or is there something else?

Well... sort of. The water regulator has the same top cap (Black with a red adjuster) as the RAVE valves on your engine. BUT... it is not a "Rave" valve.

A "RAVE" (Rotax Automatic Veritable Exhaust) valve, is an adjustable valve in the exhust that changes to port timing.


The thing on the water box is a water regulator and it changes the water flowing into the pipe.

 

[Minnetonka4me]

i have replacements if you need one...

 

[2001GTXseadooRFI]

Well I figured that. But having never taken the regulator off or apart. And by quick observation looking the same as the RAVE valve. That's what I went with. I have a look at it tonight. I'll have to check out my shop manual too and see how the regulator works.

 

[Rich B]

Can a bad RAVE result in high exhaust back pressures?