1998 GTX Limited Pump Rebuild

[amcreativ]

Hey guys!

Last year, there were so many amazing people on here that helped me get my 1998 GTX Limited back up and running after the countershaft balance blew through the block. You all helped me get the new motor in, dialed in and had a great rest of the riding season.

This year I am looking to do my wear ring. I am planning on buying the OSD Master kit #3 for 1998 2-stroke 155mm pumps. However, I have heard some conflicting information whether the wear ring they provide is better than a Delrin or not. I've watched and read some tutorials that said to avoid the OSD rings and stick with the OEM, which I assume is Delrin. Either way, I am getting the full kit.

Could someone please advise?

 

[SabrToothSqrl]

I like the delrin ones. they don't split apart and end your day like the oem ones when struck.

 

[amcreativ]

I like the delrin ones. they don't split apart and end your day like the oem ones when struck.

Exactly what I was looking for! You're not the only one to say get a Delrin ring instead of the "upgraded" OSD ring.

 

[mikidymac]

I go the other way. The OEM style ones are less likely to damage the impeller because of the soft rubber and are better for small objects. They only really blow apart from old age or major damage. It's all a personal opinion.

 

[SabrToothSqrl]

I go the other way. The OEM style ones are less likely to damage the impeller because of the soft rubber and are better for small objects. They only really blow apart from old age or major damage. It's all a personal opinion.

Usually I see the black OEM ones split from sucking up a rock or stick, and they usually have "no go power" in the water after that. It's kind of a once and done scenerio.

You're correct that a delrin one might allow more impeller damage, but from what I've seen over the years, the prop usually comes out with just scratches. The delrin one for me was the one because I'd rather lose just a bit of performance than lose my day on the water. (Unless you're packing a spare ring or jet pump).

But yea, it's personal preference... and where do you run? Suck up a lot of small rocks? Lots of branches? Never sucked anything up? I used to carry a spare jet pump when I had 4 951 skis. I could swap a pump on the trailer in minutes, as they were all the same across 4 different skis.

 

[mikidymac]

Usually I see the black OEM ones split from sucking up a rock or stick, and they usually have "no go power" in the water after that. It's kind of a once and done scenerio.

You're correct that a delrin one might allow more impeller damage, but from what I've seen over the years, the prop usually comes out with just scratches. The delrin one for me was the one because I'd rather lose just a bit of performance than lose my day on the water. (Unless you're packing a spare ring or jet pump).

But yea, it's personal preference... and where do you run? Suck up a lot of small rocks? Lots of branches? Never sucked anything up? I used to carry a spare jet pump when I had 4 951 skis. I could swap a pump on the trailer in minutes, as they were all the same across 4 different skis.

Most lakes we run are just sand but my wife decided to run my 01' XP up onto the rocks in Laughlin last year and I was able to fish out two good size river rocks out of the pump and no damage to the wear ring but bent a blade on the impeller so we finished our weekend trip. Yes, on long weekends I take along new OEM wear rings, LOL.
The only OEM ones I have personally seen blow apart were really old. If I was going on the cheap or just wanted an emergency backup then I would recommend the delrin.

 

[amcreativ]

Usually I see the black OEM ones split from sucking up a rock or stick, and they usually have "no go power" in the water after that. It's kind of a once and done scenerio.

You're correct that a delrin one might allow more impeller damage, but from what I've seen over the years, the prop usually comes out with just scratches. The delrin one for me was the one because I'd rather lose just a bit of performance than lose my day on the water. (Unless you're packing a spare ring or jet pump).

But yea, it's personal preference... and where do you run? Suck up a lot of small rocks? Lots of branches? Never sucked anything up? I used to carry a spare jet pump when I had 4 951 skis. I could swap a pump on the trailer in minutes, as they were all the same across 4 different skis.

I run big lakes, fresh water. As far as I know, I have never sucked anything up. I'm seeing a very small gap of light between the prop and the wear ring now. I bought this ski used last July, ran it all last summer, noticed a few slips that seemed like cavitation towards the end of the summer. It doesn't appear to be in bad shape, just ever so slightly worn. There is a black wear ring in there now of some sort. I have no idea when the previous owner changed it last.

What I do know is that before I winterized it, in the nose cone, was a tiny bit of water and that's it. Nothing else. Bearings don't seem damaged, they have zero play, but I still might do them any way with the OSD master kit. I filled it up with the recommended oil before putting it away. I haven't had it on the water yet, because even though daytime temperatures have been 70's here and there, the water is still very much only 40's or 50's.

 

[mikidymac]

Should be fine. The rule of thumb is any gap larger than the thickness of a dime is an issue, you are going to see light through the gap.

 

[SabrToothSqrl]

You'll know when the wear ring gives up. You'll hit 7200 RPM and feel like it's got no GO.

 

[amcreativ]

So this is what the ring and impeller look like on this '98 GTX Limited. I had it out on the water today and she definitely doesn't have the get up and go and top speed it had at the beginning of last summer. With each ride at the end of August into September 2020, I kept losing more and more top end speed.

Starts fine, runs fine, no bog or hesitation. Just not the same ooomph it had.

 

[mikidymac]

It really doesn't look that bad to cause t to be getting slower and slower.

Are you still reaching max rpm and it just isn't going like a slipping clutch or is it struggling to reach full rpm?

 

[amcreativ]

It really doesn't look that bad to cause t to be getting slower and slower.

Are you still reaching max rpm and it just isn't going like a slipping clutch or is it struggling to reach full rpm?

I’m definitely not making max RPM. 6000 if I’m lucky. Before it started to drop, I was getting 7050 and 57-60 mph. Now it’s cruising full throttle around 5980 and 44 mph. It was dropping with each ride last September before putting it away.

Did a compression test at the end of last summer. Borrowed it from a friend so I’m not sure on the accuracy. Mag was 125 and PTO 135. This is a CVTech short block remanufactured motor.

It feels like it shoots out of the gate not too bad, but it’s almost like it hits a wall at 6000 and has no more to after that like it used to.

 

[mikidymac]

Sounds like you have an engine going south. This is not pump related.

Perfect compression is 130 with an accurate gauge. The 10 psi difference is more concerning and usually as symptom of a piston going.

 

[SabrToothSqrl]

yeah, that's not a wear ring problem. it's a horse power problem... :-/

on a perfect day under perfect conditions a (OEM) 951 will hit 7k under load and about 60 mph. in a GTX. assuming you've sacrificed the appropriate gifts to the bilge gods.

 

[amcreativ]

yeah, that's not a wear ring problem. it's a horse power problem... :-/

on a perfect day under perfect conditions a (OEM) 951 will hit 7k under load and about 60 mph. in a GTX. assuming you've sacrificed the appropriate gifts to the bilge gods.

Which I hit mostly all last summer no problem after the rebuild. After a month and a bit is when it started slowing down. Bummer. I'll probably sell this thing at a discount and cut my losses. It's been a money pit even with a new motor.

The new motor is still within it's 1-year warranty. I might rip it out and send it back to them.

 

[amcreativ]

I did just notice a significant exhaust leak at the manifold and tuned pipe. Seems like the gasket has failed or perhaps wasn't installed correctly. There isn't any smoke, but it does appear to have water coming out from it and down onto the carbs. Just trying to wrap my head around this instead of a failing motor, hoping maybe it's something so silly.

 

[mikidymac]

That is a sure way to kill a 951 and a very common spot for water ingestion. Seadoo even developed "The Diaper" for this very reason.



You also need to make sure you have all the rubber flaps on the intake to keep water out.

 

[amcreativ]

That is a sure way to kill a 951 and a very common spot for water ingestion. Seadoo even developed "The Diaper" for this very reason.
View attachment 53214


You also need to make sure you have all the rubber flaps on the intake to keep water out.

Yeah I'm aware unfortunately. The flaps are intact and the diaper is as well. I have a new gasket on the way and will follow the torque sequence as laid out in the manual. I'm also going to rip the carbs off and have another rebuild done with genuine parts. If it still seems low on horsepower, it's going back to CVTech for warranty inspection.

 

[SabrToothSqrl]

I put 01+ exhaust manifolds on all my 951s I personally owned. Hard to find anymore, but they use a rubber gasket and recessed area vs the 98-00 version. While they are technically interchangeable (with correct gaskets). it's a hassle to find the preferred one. you gotta look REALLY close on eBay/photos.

Wish I never sold my best 2 skis . I told the guy if he ever thought about selling them to call me first.

 

[amcreativ]

I put 01+ exhaust manifolds on all my 951s I personally owned. Hard to find anymore, but they use a rubber gasket and recessed area vs the 98-00 version. While they are technically interchangeable (with correct gaskets). it's a hassle to find the preferred one. you gotta look REALLY close on eBay/photos.

Wish I never sold my best 2 skis . I told the guy if he ever thought about selling them to call me first.

I too wish I had the exhaust manifold with the rubber gasket. When I bought the short block from CVTech last summer they sent the original style and the rubber. That's when I discovered the newer units had that style.

I'm still going to rebuild carbs, rebuild pump and see what happens. Fuel lines and the rest were done last summer. The motor has maybe 40 hours on it, if that, it went in the ski in August, it was off the water by mid September. It was about a month old and it started to lose RPM and speed. It was running 7050 RPM at 60 mph at it's peak. Now it's 5900 RPM and 44 mph. It has a 1-year warranty, so if it comes down to it, it's going back.

 

[amcreativ]

Best of news! A new exhaust gasket and a pump rebuild and it instantly came back to life today. Over 60 mph and I believe I saw 7080 RPM on the tach at one point. For sure around 7050 RPM where it usually cruises at full throttle.