1996 Seadoo Challenger huge Cavitation issue.

[Little Dipper]

I need some help!! Please!! I have a 96 Challenger 787. new pump, new wear ring, new OE 271000660 impeller. It will not plane out hardly at all. I go it two a couple out of like 50 tries. It will plow till around 15MPH the pump will blow out air and cavitate badly. Also I'm taking on water but see no hull breach and the carbon ring seems to seal fine. I bought this for myself and my 10 year old son to enjoy but he just told me he doesn't even want to get back on the boat. So I am determined as ever to figure this out and get it back on the lake to enjoy. I can really use your help. I have read other cavitation issue threads but I just need some advice on my specific setup. would a different pump setup be better like different pitch impeller? The engine seems to have quite a bit of smoke to like its running rich but has plenty of power. I have no idea what is excessive or not. Any help would be greatly appreciated!

Thank You!!

Monte (Little Dipper)

 

[JBoss]

Did you replace the neoprene seal before putting the pump back on?

 

[mejim707]

I need some help!! Please!! I have a 96 Challenger 787. new pump, new wear ring, new OE 271000660 impeller. It will not plane out hardly at all. I go it two a couple out of like 50 tries. It will plow till around 15MPH the pump will blow out air and cavitate badly. Also I'm taking on water but see no hull breach and the carbon ring seems to seal fine. I bought this for myself and my 10 year old son to enjoy but he just told me he doesn't even want to get back on the boat. So I am determined as ever to figure this out and get it back on the lake to enjoy. I can really use your help. I have read other cavitation issue threads but I just need some advice on my specific setup. would a different pump setup be better like different pitch impeller? The engine seems to have quite a bit of smoke to like its running rich but has plenty of power. I have no idea what is excessive or not. Any help would be greatly appreciated!

Thank You!!

Monte (Little Dipper)

You say you're taking on water, how much? Is it filling the bilge are or just a few cups? The scupper on these can leak water into the boat and then drain through the center cargo area into the bilge. Especially if you're sitting. It should seal but could allow water to pass by.

 

[Little Dipper]

The water has come up to the bellows over the bilge pump. I realize it will not plane out with that much water. Originally after I bought the boat.... found freeze plug on bottom of exhaust had a hole. I had it welded. It still is taking on water. When sitting at dock I would just look in the engine bay to see If i can see water coming in...I could not. I wonder if water could come in through the bilge port outlet at the stern. Maybe its back feeding into the bilge pump and in boat.

 

[Little Dipper]

Did you replace the neoprene seal before putting the pump back on?

Yes JBoss.. I installed a new neoprene seal between pump and shoe housing. One thing I haven't done is put any additional silicone to seal it up better. Also the shoe plate around the hull has little gap between plate and hull through the pump inlet where the debris grate is. I have not put any silicone in that gap where the shoe plate meets the hull to make it a smooth surface. Any advice about that?

 

[mikidymac]

Don't put silicone on the neoprene seal.

If you are taking on water and getting cavitation it is your carbon driveshaft seal.

 

[Little Dipper]

Don't put silicone on the neoprene seal.

If you are taking on water and getting cavitation it is your carbon driveshaft seal.

Would you be able to physically notice a leak around the carbon seal like water intrusion?
I have thought about that but I didn't see it leaking so I dismissed it. I appreciate your help!

 

[mikidymac]

Sometimes they only leak when running. Sometimes the leak air into the pump and cause cavitation but don't leak water into the hull. So go figure.

 

[Little Dipper]

Sometimes they only leak when running. Sometimes the leak air into the pump and cause cavitation but don't leak water into the hull. So go figure.

ok,,sounds good... i will replace it...thanks for your help.. I will let you know!

 

[mikidymac]

I would inspect it before just replacing things.

 

[Little Dipper]

I would inspect it before just replacing things.

If its not leaking water but possibly only air..what are the signs of a carbon ring that i should look for?

 

[mikidymac]

See of the boot has tension on the stainless hat. Look for wear on the face of the stainless hat and carbon ring.

If you want to replace it as preventative maintenance since you will have it all apart I like the ones from OSD. It is a complete kit and the stainless hat is thicker to put more tension on the carbon ring but also can handle more heat.