Hello all.... i need some help with a 96 GTX with cavitation issues. The ski has a new aftermarket wear ring that was recently replaced. I did this to decrease the cavitation about a month ago, but it didn't help. Today I pulled the wear ring, pump, shaft, etc. from ski. I checked to make sure the shaft had both bumpers on the ends and added grease and a neoprene ring to improve sealing and hopefully eliminate cavitation. Instead, it's now much worse. The ski will barely start off and get on plane. I'm at my wits end with this one. Any help would be greatly appreciated. Also, I checked the grate and shoe for an area with an air leak and found nothing. TIA
1996 GTX Cavitation Issues
- Thread starter cal31967
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gazzaskirepair
Active Member
What’s the gap between impeller and wearing 
Use a feeler gauge to measure
Is this a new ski to you, was it running correctly before ? Have you checked impeller size to confirm correct one installed
Use a feeler gauge to measure
Is this a new ski to you, was it running correctly before ? Have you checked impeller size to confirm correct one installed
First off.... then engine is indeed hitting the rev limiter correct? I can't see how grease would help seal the neoprene sealing ring and sealing that area shouldn't be an issue at all with a new ring. Was the Aftermarket wear ring the same length and is the clearance in the tolerance range? Correct impeller? Is there a lot of noise when you try to accelerate. Pictures would be cool.
Try blowing air into the partings around the ride plate to see if there are any leak paths. Please Post your findings.... this is indeed strange.
Try blowing air into the partings around the ride plate to see if there are any leak paths. Please Post your findings.... this is indeed strange.
GGuillot
Well-Known Member
I've experienced this with both of my skis this season. On my 97' GTX I had a bent driveshaft causing too much wobble at the bellow and water was getting in. If you remove the driveshaft and roll it on a flat surface you can tell it it's true or not. Or on the hose, rev it and watch the bellow and shaft movement.
On my 96' GSX, just last week for the first time I started getting a cavitation issue. I got home pulled the jet pump, disassembled, inspected the bearings, refilled the oil, and regreased at the pto. Went out today and it's resolved. What was it? not exactly sure, but the oil seemed a little low when draining it.
Low oil in the pump and a bent driveshaft can be easy to overlook, but in my experience it's been exactly my issue causing cavitation issues.
On my 96' GSX, just last week for the first time I started getting a cavitation issue. I got home pulled the jet pump, disassembled, inspected the bearings, refilled the oil, and regreased at the pto. Went out today and it's resolved. What was it? not exactly sure, but the oil seemed a little low when draining it.
Low oil in the pump and a bent driveshaft can be easy to overlook, but in my experience it's been exactly my issue causing cavitation issues.
AKnarrowback
Well-Known Member
I have a 97 GTX that was reving too much on the low end and had no "hole shot". After making sure the impeller, ring, neoprene seal, impeller boot, drive shaft and thru hull bearing/seal (carbon seal) were all good I still had the reving problem. I took the entire rear end ride shoe assembly apart and found the factory sealant had seperated from most of the plastic, the seal had 100% failed on the wedge piece in front of the pump. After cleaning out all the old sealant, prepping all the surfaces and using "right stuff" to reseal all the parts the reving problem was gone.
I have resealed my 97 GTX and 94 XP ride shoes due to low end reving problems. In both instances the finished result was very noticable and worth the time to do the work. To add, I was very suprised at how little sealant was used on both machines from the factory. The XP had air channels from the nozzle area straight into the intake in front of the impeller as assembled at the factory.
I would strongly suggest cleaning and resealing the ride shoe components. Don't be afraid to use extra sealent when reassembling. On my XP I'm probably going to destroy the ride shoe if I ever have to pull it out again, but I was 100% sure there would be no air leaks when I was done. Just be sure to check the entire pump intake for sealant that bulged out and could cause a disruption to the water flow before the impeller, smooth things out before the sealant sets up.
I have resealed my 97 GTX and 94 XP ride shoes due to low end reving problems. In both instances the finished result was very noticable and worth the time to do the work. To add, I was very suprised at how little sealant was used on both machines from the factory. The XP had air channels from the nozzle area straight into the intake in front of the impeller as assembled at the factory.
I would strongly suggest cleaning and resealing the ride shoe components. Don't be afraid to use extra sealent when reassembling. On my XP I'm probably going to destroy the ride shoe if I ever have to pull it out again, but I was 100% sure there would be no air leaks when I was done. Just be sure to check the entire pump intake for sealant that bulged out and could cause a disruption to the water flow before the impeller, smooth things out before the sealant sets up.
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How difficult was it to remove the shoe and what sealant did you use going back? Got any pictures?
So here are some pics from the ride shoe as well as the wear ring. I also meant to tell you guys that the ski was much louder than normal when I removed the seat during operation. A loud rattling sound. About to check the pump now for oil.
the wear ring went in very easily when I replaced it. I didn’t have to freeze it - slid right in. Now I’m questioning this. Also, you can see from the pics the impeller has low clearance near the outside of each blade but the inside has a considerable gap. I don’t have a feeler gauge to verify clearance but will pick one up today. I also checked the bellow and that appears to be ok. Pic attached of it as well.
the wear ring went in very easily when I replaced it. I didn’t have to freeze it - slid right in. Now I’m questioning this. Also, you can see from the pics the impeller has low clearance near the outside of each blade but the inside has a considerable gap. I don’t have a feeler gauge to verify clearance but will pick one up today. I also checked the bellow and that appears to be ok. Pic attached of it as well.
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I would be very concerned about the wear ring just slipping in. Did you put some sealant on the outside diameter of the wear ring.? My preference is loctitite 609 Cylindrical Parts Retaining Compound. I buy only the OEM Wear rings because for the difference in price I'm getting a quality product that offers the best fit and performance. I find that at times so of those slide into the pump bore.
Wear ring impeller clearance looks pretty good from the pictures. If your impeller is not slipping on the shaft I"d consider looking into the ride plate or shoe... whatever they call it. So the fact that your problem got worse to me is telltale evidence that you have an air leak. The pump became more efficient and now the cavitation is worse. I'm not a boat guy... just the mechanical stuff but you have a possible leak path that needs to be investigated. Good Luck !!
Wear ring impeller clearance looks pretty good from the pictures. If your impeller is not slipping on the shaft I"d consider looking into the ride plate or shoe... whatever they call it. So the fact that your problem got worse to me is telltale evidence that you have an air leak. The pump became more efficient and now the cavitation is worse. I'm not a boat guy... just the mechanical stuff but you have a possible leak path that needs to be investigated. Good Luck !!
gazzaskirepair
Active Member
A hacksaw blade is 15 thou so can be used as a guide
AKnarrowback
Well-Known Member
Doing the work was easy. The toughest part was getting #47 out and in because the studs go through the hull and the nut/washer inside isn't the easiest to get to.
I removed and resealed 18, 34 and 47. 34 was the piece that fell out, the seal had failed all around.
Permatex "the right stuff" works really good. It is easier to remove if you have to go into things again, but it still makes a strong seal, and it sets up pretty quick.
I did not get any pictures. I did thoroughly clean all the plastic and hull surfaces. I roughed up the plastic with sand paper, I used a surface finishing disk on a 90 degree die grinder to remove the shine off the gelcoat where the sealant would go. Do a really good job off "degreasing" anything off the surfaces so they are good and dry. Use a little more sealant than you think you need then add another 25%. Slap the whole thing together and wipe off all the extra that squishes out, make sure to get underneath, reach into the pump intake area and smooth out any extra globs.
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Update. The shoe was looser than I thought. Took it off, cleaned everything thoroughly, used 4200 and reinstalled. I also found out the oring on the jet pump had slipped out during installation and allowed water into the pump. Drained, rinsed, refilled and reinstalled. Sealed tight now. After doing all this, I believe the bellow is the issue. Mine doesn’t fit up snug against the stainless ring which holds the c clip on. I think it’s sucking air there. Not sure why it just started, but I assume a new one would put some pressure on the stainless ring and seal it? Any thoughts would be appreciated. TIA.
AKnarrowback
Well-Known Member
GGuillot
Well-Known Member
It shouldn't slide in that easy, but I've only used OEM wear rings. Usually requires reasonable force with a heavy hammer and a piece of wood like a 2x4 to bash it in.
For reasons I don't fully understand, once the oil leaves the pump and it takes on water, cavitation occurs. I've had this occur to each ski, my 97' GTX and 96' GSX, removal, inspection, and refilling with oil cleared it up.
Will this work on a 96 GTX?
gazzaskirepair
Active Member
Have you checked your engine alignment
Looking at the pic from underside it looks like the engine is to far left
Looking at the pic from underside it looks like the engine is to far left
gazzaskirepair
Active Member
It looks terrible
The book says every pump removal to check alignment but I think that’s not required but at least every second or third pull of jet pump
I think the engine mounts reduce in height over time
The book says every pump removal to check alignment but I think that’s not required but at least every second or third pull of jet pump
I think the engine mounts reduce in height over time
gazzaskirepair
Active Member
If it’s a dealer that did the work and had the pump or engine out confirm they did it
Or why they didn’t
Or why they didn’t
Thanks for the advice!
gazzaskirepair
Active Member
Special tool sorry
gazzaskirepair
Active Member
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