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HELP Horrible cavitation 97 challenger single 787

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Lifted5.4Lariat

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When I punch it in the water it takes 15-20 seconds to get on plane and revs to 7k..

Impeller and wear ring are both new along with driveshaft and the carbon ring as well appear to be new. What else could it be?

Carbon ring has decent pressure against the flange deal. Tight Clarence between the impeller and ring.

Here's some pics.































Possible neoprene seal? Not really sure what else it could be..
 
So the carbone ring is new or just looks new? Dr Honda lists few things to try to verify the carbone ring by putting grease and that on the ring. Search the post here for them. RTV looks like some squeezed a little out of control and I see some small bend in the impeller other than that it looks ok.
 
The po replaced pretty much everything in the driveline inc the shaft, wear ring and I think he just filed the impeller smooth. I would assume he replaced the carbon seal. It has great pressure against the flange..
 
I have never removed the pump to see. It appeared to have tons of silicone so I don't know. Thought I'd let everyone else check out the simple stuff first.
 
All I know is it takes this thing forever to get out of the water. I can also see some air in the water on take off. The engine will rev to 7000 instantly and just stick there until it gets on the water in 15-20 seconds ten it will drop rpms and pull back up to 7k. There is maybe a gallon max of water after every 5 hours in the bilge.
 
You mentioned that the other owner replaced the wear ring the filed the impeller. So after that did the boat plane any faster after that? or did you buy it right after he told you he did all the work?

You can't judge the carbone seal on the picture. It could just be sucking air throught it when you hit the gas real fast. I know Doc says you put some waterproof grease on the carbone seal to verify if you have a the leak, but it cause the seal to wear down faster. You can put big zip ties in the boot to help apply more pressure, or if you have a mulit grooved driveshaft you can use the other grooves to apply more tension. Either way if one of those temp fixes help than you know you need a new seal. For like a $100 buck and few hours of work swap it out since your not sure if it was replaced.
 
Do you know what the procedure is for sliding the flange down on the shaft? It appears in the pics to have multiple grooves. Since it looked so new and was really tight against the flange I just went ahead and ordered the neoprene seal. I will put a heavy duty zip tie on the bellow to try and help as well once I get it back out on the water again.
 
your impeller looks ok, but, cant tell clearance on wear ring, couple of your pics looks like may be more than .040 clearance, although .040 is the max clearance, something is (fishy) with your pump looks like to me, sealer, looks like way to much, not sure if yours takes a seal or not, i would take pump off and see, your carbone seal looks ok, but, suspicious about that pump, bout 15 minutes, you can have it off, i know on my ski, there isn't anything, no seal, no sealer, just some orings on bailers and eng supply, doesnt cost anything to pull it apart ,
 
My pumps had nothing on them when I pulled them no seal or RTV. I added the neoprean seal just becuase it was apart. Griz400 is ringht it cost nothing but some RTV the worse case to put the pump back on. It might be hard to break the seal with all of that sealer might need to make the pry tool to break it loose.
 
i looked up some info on yours, it shows all challangers have a Neoprene seal, and some have what they call a spacer ring on ride shoe, so, without taking it apart, you wont be able to see it all, im guessin the Neoprene seal at the minimum, and they say to use a sealer called ultra black on the ride shoe if it has a spacer plate
heres a chart for diagnostics
POOR START, ACCELERATION OR PERFORMANCE OF BOAT
OTHER OBSERVATION POSSIBLE CAUSE REMEDY
Jet pump cavitation:
• Poor start/acceleration of boat • Trailing edge of impeller is
damaged
• Check/Replace
• Poor top performance of boat
and/or stator vanes erosion
• Leading edge of impeller is
damaged
• Check/Replace
Jet pump ventilation: • Pump improperly sealed to ride
shoe; insufficient sealant on the
ride shoe or missing neoprene
seal
• Check/Reseal/Install a new
neoprene seal
Engine RPM is high and boat is slow
to accelerate
• Through-hull seal around drive
shaft; air comes from inside the
boat
• Check/Replace
OR engine does not react quickly
when pushing on throttle lever
(assuming that engine is correct)
• Retaining screws of ride shoe or
sealing of weedless system
cable/housing; air comes from
inside the boat
• Check/Reseal
OR engine does not keep a steady
top RPM (assuming that engine is
correct)
• Retaining screws of intake grate;
air comes from inside the boat
• Check/Reseal
 
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Had a bad cavitation issue on one side of my speedster. Solved it by pushing the rubber boot towards the front of the boat about 1/2 an inch putting more pressure on the carbon ring and wear ring. I had tried a whole lot of other tricks before getting to this one and it was the simplest solution, for me anyway.
 
by looking at your 5th and 14th pics, looks like something on your hull has been re- glassed or something, think you need to tear it down, without seeing it all apart, hard to say, but by diagnostic chart, and the problem you stated, it points to through hull carbone seal area, and there is some new glass work, looks like anyways
 
I bet he had the repair done to the drive shaft insert. If the drive shaft freezes in place to the OEM insert you have to cut the old one out and epoxy the repalcement one in. Probably just need more tension on the boot. Also with those single engine ride plates sometimes need to be resealed if you have cavition you can't get rid of. Samething doesn't cost anyting but RTV to correct.
 
in picture number 12, what is the hole with cable in it >??? and should it have a grommet, ??? where is it at and is it the tunnel of water going to pump ??? if it is, then may be sucking air right there
 
I'll try putting more tension on the boot. The carbon seal is new I learned as it still has the beveled edge. So I will tighten it up some and try it and then try the neoprene seal if that doesn't fix it.
 
Pull the nozzle off the pump and check clearance of the wear ring back there, that could be part of your problem, but it sounds like the leak may be at the carbon seal, as bad as the cavitation sounds. You shouldn't be able to pull the seal back very easy from the flange if it has the right tension.
 
What would be the correct way of tightening the carbon seal since it already appears fairly new? Slide the frog flange back or loosen the bellows rear mount an scoot it forward? And put a big zip tie on a bellow to apply more pressure?
 
Why are you saying the carbon seal is new because it still has its beveled edge??

That's a load of bs right there. Just because it has material left on it doesn't mean it's sealing..... You any go on appearance.... Just because it looks good to go doesn't mean it is. Take my buddy for example. His ex looked great. Ever greater naked. (so I'm told). But then the burning started. Now he doesn't think so highly of her anymore......


If your unsure. Pull it apart and put new carbon seal, bellows boot. Stainless ring. And wear ring in. Oh and the o-rings. Put it back together with the proper neoprene ring and all it a day. I'd put money on it that's where your issues stem from.... Done and done. .
 
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If you want to put more tension on the carbon check and see if the driveshaft does'nt have another groove on it for the "c" clip to go into. Some shafts have 3 grooves.
 
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