loss of thrust on 1996 Sea Doo Challenger

[Scubadave16]

My boat was running pretty well at the end of last year. This spring I put it in the marina and it seemed to idle fine. When I gave full throttle, it got up to 7000 RPM and initially got on plane, then when I turned sharply, I felt "something" and lost most of my thrust. The engine still gets up to 7000 rpm, but only get maybe 15mph. It seems that there is a lot of turbulence around the rear of the boat. At first I though the reverse "gate" had slipped down, but when I reached down it was moving normally. the boat moves pretty much normally at idle or slow speed, and the engine revs up normally. I am able to put it in reverse, but not much thrust there, either. it runs smoothly, just has no thrust. Initially I pulled it out of the water and shined a light up the pipe. nothing seems wrong with the impeller and nothing is stuck in the intake. Any ideas?

 

[Roush2]

Did you take a good look at the wear ring?

 

[snikwad003]

Your drive shaft seal could be a source of cavitation also, or the splines could could be stripped on the driveshaft.

 

[mikidymac]

The most common cause of this is a worn or damaged wear ring as Roush said. Get under the boat with a flashlight and look from the front back into the impeller. If there is more than the thickness of a dime gap between the impeller and housing it is shot.

 

[Scubadave16]

The most common cause of this is a worn or damaged wear ring as Roush said. Get under the boat with a flashlight and look from the front back into the impeller. If there is more than the thickness of a dime gap between the impeller and housing it is shot.

Would the loss of thrust happen suddenly, though? I would think that wear would cause a gradual loss of power. I guess I have to pull the thing out again to check or can this be done while it is in the water?

I am sure there are threads on this, but is that a do it yourself repair or am I looking at another summer missed waiting for the local shop to fix my boat?

 

[mikidymac]

Actually no. When the OEM ones get really old they blow apart almost instantly with no warning.

 

[snikwad003]

The wear ring is a pretty simple job that can be done with the only special tools being a impeller tool and a pop off tester to be certain the pump is sealed

 

[Chester]

Would the loss of thrust happen suddenly, though? I would think that wear would cause a gradual loss of power. I guess I have to pull the thing out again to check or can this be done while it is in the water?

I am sure there are threads on this, but is that a do it yourself repair or am I looking at another summer missed waiting for the local shop to fix my boat?

You most likely picked up some debris for it to happen suddenly. A small stick stuck to the front of your impeller will cause you to have no thrust above idle. Crawl underneath and have a close look at the impeller all the way around. If nothing is there, put it back in the water and try it again. Many times just the act of putting the boat back on the trailer will wash out the stick.

Chester

 

[Scubadave16]

You most likely picked up some debris for it to happen suddenly. A small stick stuck to the front of your impeller will cause you to have no thrust above idle. Crawl underneath and have a close look at the impeller all the way around. If nothing is there, put it back in the water and try it again. Many times just the act of putting the boat back on the trailer will wash out the stick.

Chester

Thanks Chester. I run it in lake Michigan. very clean water over sand bottom and usually over 10 feet deep. I pulled the boat out originally and looked in the intake and impeller outflow. didnt see anything stuck in there. I will admit I didnt CLOSELY inspect the wear ring. guess I pull it out again!

 

[Scubadave16]

OK thanks for the info. I got a tiny endoscope and poked it up the jet outflow. sure enough, as you said, there is a large chunk missing from the wear ring- see photo below. So now I have to decide if this is a job I can tackle. So assuming I do, are there any recommendations on which impeller/ring i should purchase. I am assuming that if i tear the whole pump apart, I should replace the impeller. or should I? Is there anything else I need to replace while i'm in there? I am more concerned with low end power than speed. not sure if that makes a difference. I normally run the boat in rougher open water in Lake Michigan, so top end speed is not usually an issue whereas getting up on plane is. any advice will be much appreciated.

 

[snikwad003]

Yep that ring is trashed. The OEM rings are preferred by most but there are a few people that have good luck with the elcheapo blue ones, I personally have one aftermarket and one OEM in the same boat and plan to look at the difference after use here soon. If the impeller is chewed up then now is the time to change it. You have many impeller options, new solas/skat, reconditioned/repitched OEM, any impeller that gives you great gains on one side will cost you on the other side. If you have nasty gouges on your impeller shaft or your pump has water in it you should probably rebuild the pump.

 

[pawn]

Scuba: replacing the wear ring was the easiest thing I've done on my old boat. I've followed the advice on this forum about using OEM parts though. I suggest you do the same in lieu of trial and error.

 

[mikidymac]

THe little bit in your picture the impeller looks ok.

I wouldn't worry about replacing it unless it is chewed up. Even then they can be refurbished by Scat-Trak for about $100. If your boat is twin engine I would get two wear rings and think about doing both. It is a very easy DIY.

 

[Scubadave16]

Thanks. The question is will I get better low end acceleration with a new impeller? Since tearing it down already it seems like now would be the time. Was looking at Solas 15/23 available on Amazon. Of course I don’t know what I have now so hard to compare

 

[mikidymac]

It might be a little better but nothing spectacular. Seadoo did a pretty good job of selection impellers on their stuff.

Keep in mind if it's a twin engine you have to do both and some have a different impeller to keep it running straight.