2000 Gtx cavitation. New owner, please help

[Jayman51481]

Hi everyone. I am a new first time seadoo owner. I have a 2000 seadoo gtx millenium edition. It's the carbureted 951. I just bought from a friend for $1500. He is very mechanically inclined and took great care of ski. Motor was professionally rebuilt at 200 hours. It now has 250 hours. I test rode it and everything seemed fine. I had never really driven a jet ski, so I was very reserved and never jammed on the throttle. It ran great and topped out at 60 mph. Now that i am riding more I am noticing what I think is cavitation. From a dead stop, when I give it full throttle, the engine will rev up really high with no thrust. It's even worse when riding with passenger. If I accelerate slowly up to about 20 mph, i can then give it full throttle and it will pull hard to 60mph. And forget pulling a kneeboard or skis. It won't even get above 5 mph before it revs up. It is just when you load the engine hard from a dead stop, or do a hard 180 and try to accelerate fast out of it. Plenty of thrust at 20-60mph, just not on the low end. I've read all over the Internet and I think it's cavitating. Impeller looks great!! No ding, knicks, or pits. When I shine a flash light into the pump the space between impeller blades and wear ring looks to be about half a millimeter. Is that acceptable or should the tolerance be even tighter? What else could be causing this? Any tips or advice would be greatly appreciated.

 

[AdamXP800]

You should not be able to fit a dime in the space between the 2.

 

[Coastiejoe]

You have a cavitation issue. One of three places to look. 1). Something wrapped around the impeller if the drive shaft. But I doubt this is your issue as you didn't mention a vibration 2). Wear ring concern. The gap from the impeller to the ring should be NO MORE than the width if a dime. 3). Bad carbon seal / boot issue. It sucks air from inside the hull and outs air right where the impeller is. I'm betting number 3 is the issue. You can place two wire ties around the bellow and tighten them a bit. This puts additional pressure against the carbon seal. If nothing else this is a great test to do. If it works you know what your winter project is. Replace the seal and all of it components.

Based on your inspection of things, I'm thinking carbon seal.

When they go bad it will suck air out from the inside if the hull and put air right into your impeller. Thus,,, cavitation.

 

[summer]

Sounds like a wear ring to me. Have you noticed any water leaking inside the craft? Sometimes if the drive shaft seal is bad the pump will suck air out of the hull through this seal. Never experienced just read about it. One would assume if the seal was that bad you would also have a water leak.


Yeah what he said. Don't ya love it when a post appears as you are typing yours. :thumbsup:

 

[griz400]

the thickness of a dime is .053 of an inch as is too much, i prefer .020 or less, i use the delrin wear ring and they are like no clearance when installed, mine has lasted almost 2 years now and still less than .020 .. more like .015 or less --

 

[dustindu4]

Hey I've got the same ski as you and my wear ring was toast, but I was topping out at 45 mph. I swapped out the wear ring and now I'm in the low 60s. Since you're hitting 60s already it's hard to say it's the wear ring, but I think the most likely culprit. I'd buy one from SBT and toss it in anyway. Not that expensive and only takes a couple hours

 

[Jayman51481]

I'm going to try to put some wire ties around the bellow coastiejoe said, and if problem persists change the wear ring.

 

[dustindu4]

There is another possibility here, where there's a slight chance that there's an aftermarket impeller in there. The stock pitch for our ski impeller is something like 15/21. Solas makes a 13/19 pitch impeller which gives you a higher top end but destroys your holeshot.

I do think though that your ski might be fine. Don't forget that the GTX is the biggest ski besides the 4 person LRV. It's really heavy and isn't going to snap out of the hole like a 2 seater would, that's a lot lighter by design. Since it's your first ski I'm wondering what your basis for comparison is? If none of the fixes above improve your holeshot then it's probably normal

 

[- BiRkS_]

I highly doubt you would be reaching 60 mph with a bad wear ring. Sounds like a carbon seal issue.

 

[manolocross]

This is how you tighten up the bellow with the carbon seal. Look at where I put the yellow tie strap. Just loosen the pipe clamp closest to hull and try to move it forward. Then tighten tie strap behind it. Also don't forget to pump grease in pto zerk fitting. That also moves driveshaft closer to carbon ring! Had the same problem you did and this cleared it right up!!!

 

[Jayman51481]

Thanks for pic and explanation. I will try this in morning.

 

[Jayman51481]

While messing with the rear hose clamp and wire tie, I noticed the front hose clamp wasn't very tight. And the front of the bellows has a lot of play around the shaft. I would say it wobbles about a quarter of inch around shaft. I can see where it could definitely get air in there. Is this normal?

 

[Jayman51481]

Carbon seal bellows question

I noticed the front hose clamp on the bellows wasn't very tight. And the front of the bellows has a lot of play around the shaft. I would say it wobbles about a quarter of an inch around shaft. I can see where it could get air in there and cause some cavitation. Is this normal? What should I do?

 

[LouDoo]

Well as a permanent fix you need to rebuild the drive shaft, for a short term fix try fastening a couple of cable ties around the low part of the bellows.

Lou

 

[dustindu4]

and there's 2 threads on this because.............?

 

[manolocross]

Yes that wobble is normal. It's pressure towards front stainless ring that seals it!

 

[Coastiejoe]

I merged your two threads together..

 

[Jayman51481]

Thanks. Just put a wire tie on back of bellows. There is a lot more pressure on carbon seal and stainless ring now. Going to test it out right now.

 

[manolocross]

Post up results please!!!

 

[Jayman51481]

Happy with results. Rode hard for 10 minutes. Did lots of hard turns and full throttle starts. No cavitation. The true test of riding double or pulling tube/kneeboard/wakeboard is still to come. But with just me I couldn't make it cavitate.

 

[Coastiejoe]

Happy with results. Rode hard for 10 minutes. Did lots of hard turns and full throttle starts. No cavitation. The true test of riding double or pulling tube/kneeboard/wakeboard is still to come. But with just me I couldn't make it cavitate.

Amazing what a plastic wire tie can do isn't it,,,

 

[Jayman51481]

Behold the power of the wire tie and Internet!!

 

[manolocross]

Behold the power of the wire tie and Internet!!

Lets not forget the guy who gave you the knowledge and the very helpful pic of my very dirty inside of hull. My guess is it won't cavitate anymore. Until the boot looses its tension. Can be a few years though!!!!

 

[97Explorer]

Good info! I am wondering if I have the same problem with my 1997 Seadoo explorer. ....
I had the wear ring replaced and the impeller "looked new" according to the tech who replaced the ring. Still I am hitting the rev limiter when starting from a stop.

Looking in my hull I have a different seal arrangement with a big black rubber tube and a seal carrier with 2 seals And a bearing inside. There was some grease sprayed on the inside of the guard. Have a look at the picture. Any advice please?

Leigh


Sent from my iPod touch using Tapatalk - now Free

 

[- BiRkS_]

I've never worked on an explorer, but it seems similar to the old through hull fittings with carrier bearings. Basically pump the bearing carrier until you see grease seeping past the seal, then take it for a ride. If the cavitation goes away, or is less, then you need a new seal. Also it is good to check your driveshaft for excessive wear/missaligment as this could cause premature seal wear, ending up with another air leak.

Personally, I like these seals with the carrier bearings because as long as you pump them with grease every so often, they last forever, and wont sink your ski over night! (Have the original one on my '91 GT and it sits in the water all summer. Weeks sometimes with no supervision!)