Challenger Pump Problems

[IDoSeaDoo]

Hey guys, I'm getting pretty discouraged with this boat. I finally finished rebuilding the motor, and that runs great. Got good compression on both cylinders, but am still investigating the 100degF EGT difference. No matter, the scope of this post is to address my propulsion issue. Since the beginning, I've had pretty bad cavitation with this boat. When I used to gun it from low speed, the engine would tach out and bounce on the stutter box until the boat speed had a chance to catch up. That was (I think) with a stock prop. Since then, that pump's wear ring, being old and brittle, started to come apart. I disparately tried getting the impeller off and ended up breaking two pretty large vices (of two brands, one Wilton, one Bessey). The prop is STUCK, and it will take nothing short of the highest ranking Jedi to "force" it off that hub. So I got another pump I had laying around, put a new wear ring in there and stuck the closest prop I had to the stock challenger stock pitch. It was off a 95xp and had the 10/22 pitch (challenger stock is an 11/21 I think). So there is a new wear ring, newish neoprene seal (I've had the pump off twice since installing it, but it was in good shape), good prop with sharp, straight blades (non-swirl), completely re-sealed/non-leaking weedless system, and an old-style driveshaft seal, like on the old 95's (not the carbon ring design). I don't think the driveshaft seal leaks air because it does not drip water, whereas the new carbon seal combo i bought from SBT leaked quite a bit.

So from stand still, when I gun it, it puts the nose of the boat in the air and pushes water for a good 30s while the engine STRUGGLES to plane it out. That is with just two ppl in there. The reason I say struggles is because it hits 7k rather fast, like at 3/4 throttle. I don't like running it that high when it's not planing, just feels wrong somehow, also I haven't fully broken the rings in yet. The boat will lose plane with me and another (about 350lbs combined) at 5k rpms, so it's either we putt around at idle, or haul ass. I feel that something is still wrong. There is no way anyone would buy a boat that ran like this. So what do you guys think it could be? Is the prop pitch that far off? Do ride-plates EVER leak? I mean, I suppose it's possible, but that sounds so unlikely! Could my driveshaft seal be leaking air, but not water? I'm almost at my whits end on this thing. I have a few more props I could try, like a 16/22 (or 23), a 17/23 skat trak swirl, a 17/25, a straight 17 and maybe some others. What should I investigate first? I feel that the boat is still "out-of-commission" at this point... HELP

 

[Guest_User]

the heavy challengers need full power to plane out quickly. if all is perfect you can get the boat to plane off with maybe 5k rpm, buts that takes a little effort.

did you ever check the depth of the engine as far as the carbon seal leaking... usually when new parts are installed and there is still an issue, the engine needs to be aligned...

for example, the PO on ours had a very bad cavitation issues that he just accepted, he did install new carbons/bellows/etc and rebuilt pumps with skat 17\22`s... the boat still cav`d like a pig...
"the real issue was the engine was to far forward and not enough Bellows compression to make a good seal..."

there is a procedure to follow in the shop manual to show free length of the bellows and compressed length comparison for proper carbon seal tension.

if your model calls for the carbon seal, then put back the carbon seal... when those bearing type seals fail, it`s down you go with leaving a large hole for water to come in when the attaching hose tears.

as far as rings, you want to give it throttle to put compression/gasses to force the rings outward for a good seal. do not baby that engine. Just don`t leave it at any one rpm level for to long when breaking in an engine...

first 20 minutes or so, run under 5K, let cool (heat cycles), after a cool down period, run up to 6k+, launching a little harder and pulling back the stick. never let it cruise at any rpm level yet...
let cool down another 20 minutes... after that run the engine and give it more WOT stabs getting on plane for a good few seconds and pull the sticks back and start to cruise at moderate speeds.
something like that ^^^. there are a few ways people break in engines, this is just pone example.


as far as your heat issue, water temp or exhaust temp, and also performance issue> How are the Raves??? clean and freely moving, are they adjusted correctly. this would also play games with that midrange transition if not set up correctly...

and that`s besides talking about any carb settings...

good luck!

note: get the right prop for that boat!
can you tell us what is the OEM number on the impeller?
remember to small of a leading edge pitch and the boat will blow out the impeller...

 

[IDoSeaDoo]

Engine and pump were both aligned. I aligned the pump by eyeing the alignment shaft coming through the Thru-Hull-hole. I tried to get it as centered as I could, and it's pretty darn close. Then I aligned engine so that it slides right it. I still used the old style seal. I did have the engine too far forward before though, as you said, and the whole shaft would travel fwd and allow water everywehre. Since then, I've slid the motor back as far as possible, but haven't tried the carbon seal again. I guess that will be my first order of business. Do you guys think I should change the neoprene seal after I remove pump, or are those good as long as they're in one piece? Has ANYONE ever had a problem with a Challenger's ride plate allowing cavitation?

 

[Guest_User]

def use a new neo seal...
any possible air leak source can cause cavitation.
driveshaft: are the rubber bumpers on the driveshaft on each end prior to installation? the drive shaft should be able to move a bit and not be solid or bound, but to much travel with cause issues...

 

[Coastiejoe]

Carbon seals are crucial to help eliminate cavitation issues. If everything else is right, I would be shocked a new seal doesn't fix the issue. As long as the shaft is not all pitted up.

 

[IDoSeaDoo]

bumpers are/were on. it was a new carbon seal, but the motor was too far fwd. are you guys suspecting that the old-style seal is allowing air past? I made sure that the seal lips sit on the flat part of the drive shaft (and not in one of the 0-ring grooves) It's pumped full of grease and all...

 

[Guest_User]

bumpers are/were on. it was a new carbon seal, but the motor was too far fwd. are you guys suspecting that the old-style seal is allowing air past? I made sure that the seal lips sit on the flat part of the drive shaft (and not in one of the 0-ring grooves) It's pumped full of grease and all...

I don`t suspect that is the issue right now, but you do need to get the right pitch prop back in there...
what is the OEM number off the original impeller?

 

[IDoSeaDoo]

can't know for sure as it's still seized tight to the old pump. all i can say is that its a SS Swirl type prop. i believe it's stock b/c I remember seeing stock props for challengers on ebay and they looking like the one I have. that prop is pretty chewed up though. I've sharpened the blades as well as I could, but I can't compenasate for the 1-2mm bite a rock took out of it with the PO. The one I have in there now is pretty clean with sharp leading edges, but straight, not swirl blades. my buddy suggested that maybe I'm not cavitating anymore, but rather just not pushing enough water to plane the boat out? like the pitch is not aggressive enough? could this actually be an issue? I thoguht a lesser pitch prop would shoot me up to plane faster and just eat away at top speed...

 

[Coastiejoe]

For whatever reason, finding your OEM pitch/size seems to be a hidden secret.

If you feel all is right including the shaft and seal, then I am guessing the prop is spinning to fast due to an incorrect pitch. If you could finding something more aggressive, it would be worth a try...

 

[IDoSeaDoo]

I guess this comes down a question on the principle of pump operation: if I have a prop that is underpitched, could that increase my time to reach plane?

 

[Coastiejoe]

I guess this comes down a question on the principle of pump operation: if I have a prop that is underpitched, could that increase my time to reach plane?

Absolutely,,
You will spin REAL FAST but not really go anywhere.

Think of a fan. If the blades have a minimal angle, it will spin just fine but not push too much air. Increase the angle and you will increase the air.

With props and impellers, as you increase the angle you move more water but also increase the working load. So,,, there is a happy medium where you will still be at or near the max RPM's but also get good performance.

If you use too steep of an impeller you will move TONS of water but not have the horse power to turn the prop enough to get performance..

Make sense?

 

[IDoSeaDoo]

Yep. So my next step is then to try a defferent pitch prop. I guess the RPMs will tell me if it's too steep or not. Good thing it's not too hard to remove I still feel better with the older-style seal on there. I don't think it will ever seize up, as I grease it regularly. Anyone have a good reason why I should go back to the carbon type seal? I'm not excited about the fact that it leaks by design. If I go camping, I wouldn't want my boat to sink overnight...

 

[Coastiejoe]

From what all I have read the carbon seals produce better performance results.

The older style work fine, carbon work better is how I understand it. Keeping it greased is thenkeybtonit working well.

 

[Coastiejoe]

I found many sites that sell the OEM impeller. Just none that have the size.

Seadoo has done a very good job in finding the right impeller for each of their skis and boats. You need to be able to reach max RPMs within a 100 or so to get the best over-all performance based on the factory engine.

You can change the pitch to improve bottom end torque and gain your out of the hole and pulling performance but it comes at a cost in losing some top end speed for example.

 

[IDoSeaDoo]

According to Skat-Trac...

I found many sites that sell the OEM impeller. Just none that have the size.

Seadoo has done a very good job in finding the right impeller for each of their skis and boats. You need to be able to reach max RPMs within a 100 or so to get the best over-all performance based on the factory engine.

You can change the pitch to improve bottom end torque and gain your out of the hole and pulling performance but it comes at a cost in losing some top end speed for example.

According to Skat-Trac, the OE impeller was a 11/22 http://www.skat-trak.com/seadoo_app2.html
According to the part number, the impeller I have is a 10/22 http://www.seadoosource.com/impellerref.html

Hard to believe that one degree on the leading edge would cause such a difference...

 

[Coastiejoe]

I would agree. One degree will make a difference but I would not think to the degree that Wouk justify the issue you are having.

Maybe someone with similar issues will chime in and add their thoughts.

In boats, one size difference normally affects the RPMs 200 to 250 RPMs just to give you an example.

 

[IDoSeaDoo]

No, I can hit 7k rpms for like 30sec before it gradually starts to plane out

 

[Guest_User]

No, I can hit 7k rpms for like 30sec before it gradually starts to plane out

787`s correct? I`m going to take a stab at this and say the transition of when the Raves open could be screwing you up. I can feel when the raves open, it`s like a small shot of NOS, zoom and I`m gone, but when you throttle back, you can get in that zone where the valves open/close/open close and watching the tach drop off and rise with rpm.

Now maybe with gradual speed increase your not getting the valves to open or it`s in that transition that`s keeping the boat from getting on plane below 6k rpm, then the rpms jump to 7K when the valves pop open...
maybe^??

I found this reference chart:

http://www.seadoosource.com/impellerref.html

here is another:

http://www.solas.com/newweb/pwcproduct/search/brand.asp?FkindNo=F23&SwType=1


it looks like the OEM impeller for your boat is 204160027

 

[IDoSeaDoo]

Hmm, but that would explain things only if I wasn't able to attain those RPMs. If I'm spinning the prop at 6k or 7k, it should push the boat accordingly, raves or not. Somewhere, I'm either still pulling air, or it's just not pushing enough water. I'm leaning with the former. The following is my known list potential sources of cavitation:
Wear Ring
Pump Seal (neoprene)
Impeller blades not sharp
driveshaft seal
weedless system leak
rideplate

Are there any more? I feel like I've attended to all but the rideplate. I have a hard time believing or envisioning where it could even pull air from...

 

[Guest_User]

IDoSeaDoo, would this impeller work out for you? 204160050 These were OEM on our 98 challenger 1800.
I`ve since replaced them with Solas 15\23 Concords after I puked a driveshaft and killing the splines in one of the impellers.

 

[Guest_User]

Hmm, but that would explain things only if I wasn't able to attain those RPMs. If I'm spinning the prop at 6k or 7k, it should push the boat accordingly, raves or not. Somewhere, I'm either still pulling air, or it's just not pushing enough water. I'm leaning with the former. The following is my known list potential sources of cavitation:
Wear Ring
Pump Seal (neoprene)
Impeller blades not sharp
driveshaft seal
weedless system leak
rideplate

Are there any more? I feel like I've attended to all but the rideplate. I have a hard time believing or envisioning where it could even pull air from...

well for giggles did you check the clearances between the impeller and wear ring, maybe it`s just to large and your whizzing that 10\22 non swirl... I believe the non swirls has less overlap and that could be an issue as well...

choosing the right impeller is tricky...
hahah I cheated, I called Dave over at Impro`s and he selected the 15\23`s after I told him what I wanted from the boat... speed increase is silly, loading the engines more for a few mph wasnt worth it... light weight jetski`s with less surface tension are different.

 

[IDoSeaDoo]

Not sure, it's a different part number than the one that they call for on the single 787. What's funny, is they used different props between 96 and 97 on these challengers. I wonder why. It sucks that noone knows their pitch. With this difference between 96 and 97, I wonder which one Skat Trac posted that 11/22 spec about... It is a pretty prop though, what would you want for it?

 

[Guest_User]

Not sure, it's a different part number than the one that they call for on the single 787. What's funny, is they used different props between 96 and 97 on these challengers. I wonder why. It sucks that noone knows their pitch. With this difference between 96 and 97, I wonder which one Skat Trac posted that 11/22 spec about... It is a pretty prop though, what would you want for it?

pm sent, lemme know...I`m not trying to sell ya an impeller, just helping a fellow boater out!:cheers:
I think the 050 is a 15\23, I think...

 

[SKETSEA]

The challenge single 800 is 17 22 swirl.

 

[IDoSeaDoo]

The challenge single 800 is 17 22 swirl.

Is that from the factory? Where did you get this info?