Can't get pump back in 96 GTX with Neoprene seal

[Lothsahn]

I took my pump out and replaced both the wear ring and impeller, because both were bad in my 1996 GTX.

I used the delrin wear ring from osd marine here: OSD Sea Doo DELRIN WEAR RING - 2 STROKE 140mm [OSD2332] - $36.99
I also bought a neoprene seal from them.

I installed the wear ring with the non-flat (grooved) part facing the hull, as instructed. However, when I put the neoprene seal in, I couldn't get the pump to seal flush against the backing plate. Even after tightening all the bolts, there was a small gap in the two lines at the top that feed the cooling water to the engine. I could feel the rubber o-rings with my fingers.

I removed the neoprene seal and everything went together as expected.

Did I do something wrong? Is my model incompatible with the neoprene seal?

 

[GGuillot]

Did I do something wrong? Is my model incompatible with the neoprene seal?

It should not matter, the neoprene seal is thin and compresses. Can you post a pic? Maybe the delrin has something to do with it, makes a difference which way it's installed in the pump housing.

 

[Lothsahn]

I'll try to get a picture of it currently installed. I installed the delrin with the ridge facing the ski. The flat side of the delrin was facing away from the ski towards the output.

Is there any problem if I don't install the neoprene seal? Will it cause cavitation? I'd rather not pull it all off again if it'll be fine.

 

[Mraw]

You need the seal or some black rtv or you will have cavitation. Although if you want you could just try it. I lost my black rtv and was in a rush to get in the water, a bit of cavitation on take off but wasn't too bad.

 

[Lothsahn]

Attached images of the pump install. Seems like there's still a small gap between the two engine coolant water lines. If the Neoprene seal is in there, it does smush down, but it makes the gap worse.

Maybe I didn't get the delrin wear ring all the way in? I put it in the freezer and it slid right in. There was no corrosion or deformation of the hub, and the clearance between the impeller and wear ring was great.

Unfortunately, as recommended by OSD, I put a very thin RTV silicone between the wear ring and the hub. I took a single drop and spread it out evenly with a toothpick, but I think it's still glued in nonetheless...

I put new o-rings in when I reinstalled the pump, but if the gap in those lines gets enough that air can come in, that may cause the engine to get insufficient cooling and overhead, right?

 

[mikidymac]

I would suspect the delrin wear ring. Another reason I only run the OEM ones in my skis.

 

[Lothsahn]

I would suspect the delrin wear ring. Another reason I only run the OEM ones in my skis.

From the pictures I sent, do things appear to be assembled right, or is there more of a gap than normal?

 

[mikidymac]

There really shouldn’t be a gap. The neoprene seal basically compresses to nothing so if that caused an issue I think something isn’t right.

 

[racerxxx]

How far is the wear ring protruding from the pump? That's where I'd look. The OEM wear rings have a small thin lip that will dig into the neoprene seal, this is something the aftermarket delrin ones don't have. I wonder if the place that manufactured yours makes theirs a tad longer and is trying to eliminate the need for the neoprene seal?

 

[Lothsahn]

The Delrim had a quite well defined ridge/groove that would push into either the hull or the neoprene seal. The non-oem plastic one (from the previous owner) I took out had no such thing--just a flat surface on both sides.

I have a picture from when it was disassembled, but it doesn't show the groove or alignment of the wear ring to hub very well at all. I've attached it.

I just took it out in the water and the cavitation problem is *massively* better--but that would be expected. The old hardware was all worn out.

The old wear ring had more than a 40mm gap between impeller and ring, the old impeller was chewed up on the leading edge, and there was no neoprene seal or silicone on the old wear ring. I also replaced the carbon ring.

With all the new hardware installed, It was an absolute blast, and it didn't cavitate in hard turns. If I floor it from a stop, the engine revs up, I get instant acceleration and it "feels right". I do notice that it seems like the engine hits the rev limiter for about 1/8 of a second, then the RPM's drop slightly as it "catches" and accelerates as expected. The "over-revving" happens between 5 and 10 mph and is fully gone by 10mph.

At this point, unless someone's going to tell me that this is going to somehow harm my seadoo, I think I'm just going to leave it. If there is any unexpected cavitation, I think it's quite small. Probably beats the effort of tearing everything apart...

 

[etemplet]

If you have a problem with the length the o-rings will not seal for the pump output or the siphon tubes for the bilge suction boxes. You should not get an over-rev condition but as you say it is up to you to fix or not.

 

[AKnarrowback]

I try to avoid aftermarket wear rings since they always seem to have a fitting problem. However, OSD is a good group so I'm guessing you have a good ring.

I would double check the length of the ring against the one you pulled out if you still have it. If it is the same length, down to the hair, then I would double check and make sure the new ring is fully seated in the pump and that no foreign material is pinched between the pump and ring preventing full seating.

If the ring is a hair long I would either get an oem liner and replace the one you have or, if the liner is a plastic material, lightly sand the end down until you have proper fitting. Now if you sand it you are not going to have a uniform end so a seal of some type will be needed. Neoprene rings do compress to a very thin layer, but to help you I would suggest a VERY light bead of the proper silicone. I say very light because too much silicone makes pulling the pump back off a real chore.



"Right stuff" is the only sealant I use on my DOOs since it sets up fast, makes an excellent seal and is easy to scrape off if you do pull things apart.

Do some more digging before you run it. The dimensions are a hair off but running it "as is" is going to leave the pump further back. Most likely not a problem, but the drive line length and "slop" in the forward/back movement of the pump impeller shaft were all designed with specific dimensions in mind.

BTW - There is a difference between "cavitation" and "aeration" (spelling?).

Cavitation = rough surface causes bad water flow. Aeration = Air is getting into the water flow from an external source, like spinning your tires on ice. Both feel the same but have different root causes.

Let us know how things work out.

 

[Lothsahn]

I try to avoid aftermarket wear rings since they always seem to have a fitting problem. However, OSD is a good group so I'm guessing you have a good ring.

I think so too. The old blue plastic ring was crap and while it had ZERO wear marks, it had variation of ~.030 inches in thickness (defective from the factory). The new OSD one was perfect clearance just barely scraping the edge of the impeller when it installed. You could hear the slightest faint scratching sound as you rotated the impeller, all the way around the whole ring.

I suspect I didn't get the ring fully installed. I wasn't aware of the tight tolerances and I pushed in easily in by hand (I had put it in the freezer). I thought that banging on it with my palm was sufficient, but I now realize I should have used wood and a mallet. I bet you anything that's the problem. Since I put a small amount of silicone on the ring, I suspect I can't move the ring now that it's installed.

Not a mechanic. Live and learn.

If the ring is a hair long I would either get an oem liner and replace the one you have or, if the liner is a plastic material, lightly sand the end down until you have proper fitting.

This is a great suggestion. Is there some way to ensure that I sand it evenly around the whole ring? I don't want to create a gap that makes the aeration worse. I will use the neoprene ring after sanding it.

Do some more digging before you run it. The dimensions are a hair off but running it "as is" is going to leave the pump further back. Most likely not a problem, but the drive line length and "slop" in the forward/back movement of the pump impeller shaft were all designed with specific dimensions in mind.

Okay. The pump's coming off. I'm not going to mess up my driveshaft or engine due to laziness. Wish I could go back in time and tell me from 3 days ago what to do differently.


Thanks for the clarification on aeration vs cavitation.

 

[AKnarrowback]

Live and learn my friend.

Always give the liner a light tap in to seat it in the pump, even after putting it in the freezer. You do not need to silicone the liner in place, once the pump is tightened down the liner is pinned between the pump and hull so it's not going anywhere.

As for sanding it? No good suggestion there. Even at my most creative level of winging it I doubt I could sand one evenly. If shipping is fast enough I'd order a new one if you have to really work things around.

Not that knowing the technical name between the two isn't so important, but I have seen people get led in the wrong direction or try the wrong fix with pump performance. Knowing when to look at impeller damage - vs - a bad liner - vs - an air leak into the pump - vs - the wrong impeller pitch is important when figuring out poor or a change in performance.

 

[Lothsahn]

Got the pump out.

Attached some pictures of my pump. I felt the back of the wear ring (from the bottom side of the pump), and I don't feel a gap. Took a bunch of pictures--you can see the lip on the delrin wear ring (my previous wear ring didn't have a ridge like that).

I looked through the impeller and spun it around, and there's definitely no gap between the wear ring and the bronze casting all the way around. It looks like it's fully installed. For good measure, I malleted it with a wood block, but it didn't move.

Note: The picture of the hull looks like the plastic is cracked on the bottom left, but it's not. They're just scratches and shadows interacting weird.

Is the wear ring protruding more than other wear rings? Where would you go from here?

 

[mikidymac]

I have never seen a wear ring come to a point like that. I still suspect the ring.

 

[Lothsahn]

I have never seen a wear ring come to a point like that. I still suspect the ring.

Wonderful. Could I cut it down with a razor blade? Any way that I can make this work without removing and replacing the ring? I put red loctite on the impeller and a very thin layer of silicone between the wear ring and housing as instructed and the impeller was an absolute PITA to get out the last time.

 

[Lothsahn]

Took it all apart, found a little debris sitting at the bottom of the hull. There was a little bit of silicone crumbles and dirt in there. Got it nice and clean, then blew it out with a leaf blower. Put it back together today WITH the neoprene seal, no sanding or cutting of the wear ring.

No gaps! Gonna take her out to play now...

Thanks again for all the help @mikidymac, @AKnarrowback , @GGuillot, @Mraw and @etemplet !