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  1. #1

    Messed up impeller low speed problem?

    Stupid me thought you checked the impeller from the back of the boat when I bought it. I just looked at it from the front yesterday and noticed that one blade has a nice dent in the leading edge and another several smaller ones and is slightly bent. The boat with a couple people planes very quickly and top speed is 41 with full tank and 2 people. However, it really sucks at low speed. At 4000-5000 RPM it is just moving like 5mph. Not until you get around 6000+ RPM that is gets up and goes. Would the buggered up impeller be the cause of the poor slow speed performance? Would a new impeller allow me be get out of the harbor at the 5 mph no wake speed without the engine revving so high?

    I'm thinking about getting the
    Skat Trak Swirl impeller. I read that Skat Trak does not manufacture an impeller with the correct pitch for the 14.5 boats such as my Challenger. According to Group K, they re-pitch to the correct spec for your boat. They seem to be about $50 more for the same impeller compared to other places. What do you guys think about the re-pitching thing? True or an extra way for seller to make extra off the sale? I read elsewhere that for best bottom and midrange performance the 14.5/22.5 was best. I wonder what Group K re-pitches them to???

    How long does the average Joe at home take to replace the wear ring and impeller? I noticed that the dealer labor cost for that job was $350. So I'm guessing it is about a 3.5 hour job on paper which means they probably do the job in about 1.5 hours. I'm guessing doing it for the first time at home would take something like 4-6 hours?

    I was looking up the Swirl impellers online and I think my Challenger may already have one of those. The blade is rounded out like in this photo. I think the stock impeller has a straing leading edge? If so, that may explain why it planes quickly?

    Last edited by PilotSmith; 02-09-2008 at 02:22 AM.


  2. #2
    Oopps , photo did not post on last post. Here is a photo of my acutal impeller. You guys think it is a Swirl? Can a buggered up one be fixed by taking it out and undenting it? Not sure how bad mine is as I don't know how much damage they can take before really messing up performance.
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    Last edited by PilotSmith; 02-09-2008 at 02:33 AM.

  3. #3
    Sure looks like a swirl to me...I'd say to pull it, send it to Impros & get it fixed or atleast get the pitch adjusted.

    It could be that it's too 'tall' of a prop (designed for top end) for your boat. The previous owner might have installed it & regretted it so he sold the boat. While you're in there, do your wear ring too.

    Couldn't tell you how long on your boat (never done one), I can pull the pumps on a Yamaha in about 20 minutes. The hardest part will be if the impeller is seized to the shaft.

  4. #4
    Jeepster's Avatar
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    On most Sea-Doo PWC and Jetboat, getting to the impeller itself and removing the pump is about 20-30 minutes max. the first time you do the job, once experienced, you can take the pump off in about 10 minutes....it is a very easy job.

    Check in the how to section i'm sure you'll find the info needed.
    Basically you remove the reverse bucket, then you remove reverse cable and steering cable from the venturi, then unbolt the complete venturi unit with 4 bolts (steering nozzle and cone shaped part), and finally unbolt the pump itself (containing the impeller and wear ring) again with 4 bolts, and pull that out as a unit.

    To get the wear ring off, (some older pumps have little screws that are screwed from the exterior of the pump into the plastic wear ring, so these might be removed prior to go to the freezer) put the complete pump into the freezer for about 30 minutes, the plastic wear ring will shrink in cold, and when you take it back out of the freezer, you'll be able to pull out the wear ring out of the pump by hand. For the impeller to be removed from there, you'll need to buy an impeller spline tool that you will slide into the impeller splines and put in a vise (to hold the impeller from turning), and on the other side of the pump you need to remove the cone and oil or grease,put in a big allen key to hold the bearing side, then you unscrew the impeller from the bearing unit of the pump.

    Then you have all the parts in your hands....i'd say total time would be maximum 30 minutes unless something is seized and need some WD-40 and some struggling a bit. Once you are there refill the pump nose cone with fresh oil or grease, but prior to that check the pump bearing for any wear, this is the time to change it if it is damaged.

    CIAO.

  5. #5
    The ski's have taken a "backseat" to the Corvette DarthAWM's Avatar
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    You should check with Impros they repair and repitch impellers would be much cheaper than buying a new one.

    I'll post a Impros link after I look it up

    Ok it was hard http://www.impros.com/

  6. #6
    That sounds pretty basic and quick! When I saw the $350 labor alone price to replace the impeller I thought is was a bigger job. I am only about 1/2 hour away from Impros so I will pull it out and let them take a look at it. If mine can be repaired that would be great. I think the pitch on it is fine as is. Once all the dings are out of the blades perhaps it should run even better. Does this look repairable?

    Since the 1st run I replaced the spark plugs with new ones properly gapped. Also replaced the airbox that prior owner drilled out with many 1" holes. Took it out yesterday. Ran perfect, unlike 1st time out were the motor stopped running twice, this time ran smooth entire time. We went 50 miles over about a 3 hour period. Perfect SoCal day in mid 70's, 3mph wind, glass calm ocean. We had a blast. Had 4 people total in boat. (I'm 170 and passegers were 140'ish.) Took 5 seconds to plane vs 2.5 seconds with 2 people in boat. Here is speed info:

    2 people: 41.1 mph
    3 people: 40.0 mph
    4 people: 38.7 mph
    Perhaps it will pick up a little extra speed with a new or repaired impeller? Even if not it was fast enough to keep us entertained. Sure rides much nicer than our inflatable boat!

    I also did some work to insulate the engine noise. Still noisy but MUCH better than the first time out. In fact, it was quiet enough this time for me to notice a rattle in the left mirror I need to fix. This time I noticed more exhaust noise vs engine noise the first time out. I will add a little more sound insulation as time permits but it is now tolerable.

  7. #7
    Impros's Avatar
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    That is totally repairable, and the cause of the performance issues you're describing.
    I'm not sure why the dealer would charge so much to pull the pump and impeller, but our cost is 1/3 that, including changing the wear-ring.
    It is a pretty simple job for most people to pull the pump. The impeller and wear-ring are a little more difficult for a person with no tools or vice, but also do-able. It's just time, but you'll learn a lot about the driveline.
    David

    Quote Originally Posted by PilotSmith View Post
    That sounds pretty basic and quick! When I saw the $350 labor alone price to replace the impeller I thought is was a bigger job. I am only about 1/2 hour away from Impros so I will pull it out and let them take a look at it. If mine can be repaired that would be great. I think the pitch on it is fine as is. Once all the dings are out of the blades perhaps it should run even better. Does this look repairable?

    Since the 1st run I replaced the spark plugs with new ones properly gapped. Also replaced the airbox that prior owner drilled out with many 1" holes. Took it out yesterday. Ran perfect, unlike 1st time out were the motor stopped running twice, this time ran smooth entire time. We went 50 miles over about a 3 hour period. Perfect SoCal day in mid 70's, 3mph wind, glass calm ocean. We had a blast. Had 4 people total in boat. (I'm 170 and passegers were 140'ish.) Took 5 seconds to plane vs 2.5 seconds with 2 people in boat. Here is speed info:

    2 people: 41.1 mph
    3 people: 40.0 mph
    4 people: 38.7 mph
    Perhaps it will pick up a little extra speed with a new or repaired impeller? Even if not it was fast enough to keep us entertained. Sure rides much nicer than our inflatable boat!

    I also did some work to insulate the engine noise. Still noisy but MUCH better than the first time out. In fact, it was quiet enough this time for me to notice a rattle in the left mirror I need to fix. This time I noticed more exhaust noise vs engine noise the first time out. I will add a little more sound insulation as time permits but it is now tolerable.

  8. #8
    1996 Sea Doo Challenger (787x1)
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    Aside from that one big gouge on the lower (in pic) blade, my "original" impeller (which turned out to be a Skat-Trac Swirl) in my new-to-me 1996 Challenger looked pretty much the same as yours...and it got me a smidge over 45 MPH by GPS. I replaced the wear ring and got a new Swirl, and actually lost top-end; only 41 + MPH. I'm guessing the impellers can be pretty dinged up and still do a good job.

    Glad to hear you had similar experiences with the "noise abatement". I did 60 miles in mine on Saturday---with the most "stuff" mashed in there, and is sure was a lot nicer to ride in. I'm looking forward to hear how that pourable foam works out for you.

  9. #9
    Quote Originally Posted by Steve762us View Post
    Glad to hear you had similar experiences with the "noise abatement". I did 60 miles in mine on Saturday---
    Have you figured out your gas mileage? I think I got less than 3mpg on Saturday. Then again the kids were WOT for about 40 of the 50 miles we did so I am sure that didn't help. About the only time not WOT was for 8-10 miles in the no wake zone of the harbor.

  10. #10
    1996 Sea Doo Challenger (787x1)
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    Quote Originally Posted by PilotSmith View Post
    Have you figured out your gas mileage? I think I got less than 3mpg on Saturday. Then again the kids were WOT for about 40 of the 50 miles we did so I am sure that didn't help. About the only time not WOT was for 8-10 miles in the no wake zone of the harbor.
    I've done two GPS measured runs (39 miles & 61 miles) and refill quantities suggested around 4 miles/gallon...this was starting with full 27 gallon tank, and just me onboard (~200 lbs) along with about 30# of tools/possibles stuff. I normally run it just below half throttle, which puts me around 35 GPS MPH. As a boating noob, I have not a clue whether this is respectable or horrible mileage.

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