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  • motor won't start

    Have 9l XP with 587 motor. Craft sat for couple of years. Won't start.

    Have done all the usual diagnostics. Stop switch, lanyard switch, fuel, spark plugs and wires etc. Have also swapped out coil, cdi, rectifier, rev limiter. Still nothing.

    Can find two obvious problems with motor.
    Compression is very low 70 in rear/ 90 in front. Also appears to be a oil leak comming from someplace.

    Under crank, motor seems to want to start--smoke comes from exhaust--but won't start.

    On Seadoo net suggestion was made that one cause of non start could be a brass gear on the rotary valve. Would appreciate more information on this. Is it something that can be done with the motor in the craft, or will the motor have to be pulled.

    With low compression, I know motor will require at least a top end rebuild--most probably a replacement motor. Since any replacement uses the existing rotary valve components, would like to know extent of starting problem before decision made to go for a replacement.

    Any help appreciated

  • #2
    Glad to see you here!

    OK, first things first - ditch that gauge! From what you posted about how it was acting, it is completely unreliable for diagnosing this problem. If you go buy another, make sure that you #1, have the correct length fitting on the end for your engine - and #2, get one with the Schrader valve on the end of the tube, not up by the gauge. These two things will help insure you get reliable, accurate readings.

    As far as the compression, if they truly are at 70 and 90, there is a pretty good chance the it would at least start and run on it's own, if that was the only problem. I suspect it is not, however.

    For the oil leak, where can you see it coming from? You oil system consists of three parts: the tank, the pump, and the reservoir in the case. If your tank is leaking, it is most likely to be at the seams of the plastic tank, or at the line fittings. It's pretty easy to wipe everything down and watch where it leaks from. If it's the pump or lines leaking, same deal - wipe it all clean and see what gets oily. Lines are known to break at the very tips - they can get hairline cracks that leak under pressure. Your oil reservoir in the case keeps a static supply of oil to lubricate the rotary gears and shaft. If that is leaking internally, you get fouled plugs, a ton of white smoke while running, etc. It it's leaking externally, it will be at the two large oil line fittings going into the case.

    The brass rotary valve gear is meant to be stripped to save the other internals, in the event the engine seizes or debris stops the rotary valve while it's running. The shaft/brass gear assembly can be changed while the engine is in the hull, however it requires a special puller to do so. Many dealers can do this for you if you choose to have it done.

    You are right - if your engine really does have compression that low, you need at least a top-end rebuild. If you also need bottom-end service, you have already surpassed the cost of a complete engine from us. And yes, we do include new rotary gear/shaft assemblies. The only things you use on our engines are the external accessories - the manifolds, pipe, carb(s), rotary valve, etc.

    It is also possible you have blown out an internal oil seal from the reservoir - if you are getting heavy smoke, or see oil spitting out the plug holes while cranking, this is a good indicator.

    Comment


    • #3
      Bryan,

      Oil leak seems to be external. Oil collects on bottom of hull. You are probably correct in that leak comming from a hose. Leak minor problem.

      With regards to rotary gear, is there any way I can isolate that as my problem?? With the motor in the boat, if I take the dual carbs and intake off can I see the problem??

      I have a clymer manual. I would appear that the motor has to come out and crank remover to replace the part???

      Also, on you installation instructions, you indicate a degree wheel. Just where does a weekend mechanic like me get something like that?? Any other special tools needed??

      Thanks, Tom

      Comment


      • #4
        You can tell if the rotary gear has jumped timing at all by measuring the valve timing, as you mentioned, with a degree wheel. Most dealers stock them, we sell them for $10 - it's a minor part. It's basically a hard plastic 360 deg. compass that fits snugly on the rotary shaft so you can measure the timing easily, as shown in my instructions. Basically, all you need to do is follow the instructions to check your timing - place the Front (#1) piston at Top Dead Center, then measure where the top part of the valve hits in relation to 0 deg - the bottom of the front intake port opening. If it's not at 115 deg +/-5 deg., then you have slipped intake timing, and the gear is most likely stripped.

        No, the motor does not need to come out to replace the gear, but you do need a Sea-Doo rotary shaft puller to get it out. If you determine that your gear is bad, and you want to have a dealer do a top-end on the motor or whatever, then the dealer can quickly remove the assembly for you.

        As far as other tools needed to remove and install a 580, they are all listed in the back of the guide. Nothing special other than the degree wheel.

        [ February 19, 2001: Message edited by: Bryan Glynn - SBT Webmaster ]

        Comment


        • #5
          Bryan,

          Thanks for getting back to me so quick.

          As you can appreciate, given the age of this craft, I don't want to create a money pit. If I had this problem on my 98XP or my kids SPI's I would probably be putting an order in for a SBT replacement motor.

          As far as rebuilding the top end of the 9l XP. All I really need are standard rings. I have pulled the head and domes--everything looks good. I would figure with a good honing, I could probably get away with replacing just the rings. I have already rebuilt a Kawasaki 650 top end with good success--I know I could do my Seadoo's top end.

          The rotary valve replacement has me concerned. Now I know that I can get the degree from you if necessary. The puller could be a problem. I will have to check to see if I can obtain (rent) one from a local dealer or have him pull it for me.

          In your last post, you indicated that the gear can be removed with the motor still in the craft. My Clymers indicated that it is necessary to remove the motor and split the crankcase in order to remove the gear. Who is correct--I hope you are??

          I would love to get this ski back running, but I would hate to put good money into a bad cause. If I can do most of the repairs myself, it is cost effective. To put $800 to $l,000 into a ski that has a value of less than that flys in the face of common sense. An sbt rebuilt in an ll year old ski is hard to justify.

          Can (or should) a weekend mechanic attempt the replace the rotary valve gear?? Does it involve removing the crank??

          Comment


          • #6
            It only involes unbolting the carb, and the intake. The cylers assumes that you will not have access to a puller - and you probabyl won't, as it's a special order Sea-Doo tool at best - and no dealer is going to stock it, besides in their own tool collection. Don't even consider the gear job until you verify timing - it could very possibly not be the problem. Who knows what your ocmpression really is - maybe it's more like 40 psi! You need to #1, get a good gauge and do some testing - then #2 verify your valve timing before considering anything else.

            Comment


            • #7
              One thing you should note: Even though it is possible to remove the shaft assembly while in the hull, if it is indeed stripped, you will need to open the case to replace it, as the crank gear and case needs to be well cleaned of the brass filings before the new brass gear is installed.

              Comment


              • #8
                Tom,
                For several reasons, I think you need to decide if you want this ski running or not, and are willing to buy the SBT replacement motor.
                Speaking from vast experence with these older Sea Doo's, I can say with complete confidence, that you would be money ahead to replace that motor.
                If you pulled the head and "everthing looked fine" and by that I mean no scoring, no broken rings, no apparent problems, then your motor will not pump less than around 140-145 lbs on a good guage at sea level.
                Sea Doo uses great rings, and even when they are completely worn out, they still pump good numbers. If your guage is accurate, there is damage that you are not seeing. The difference in replacing the top end and replacing the whole motor, is not worth the hassels, nor the ruined parts when a crank bearing lets go. If there is enough wear and tear on your motor to need to replace the top end, then I'll guarantee that your bottom end is about done and ready to come apart.
                If you want to avoid a money pit, get the new motor. Spend a little more now, and aviod re-spending in the near future. How much is your summer fun worth ?
                Bill O'Neal WCM
                <a href="http://www.watercraftmagic.com" target="_blank">www.watercraftmagic.com</a>

                Comment


                • #9
                  Thanks Bryan and Bill for the information. I will have to mull over your advice.

                  Tom

                  Comment


                  • #10
                    Try some ether, spray some in each plug hole and then re-install really dry/clean plugs and see if it catches. If it does, then I'd say you have a big air leak at the mag side crank seal or an intake gasket failure. Your first problem sounds like an air leak.

                    Comment


                    • #11
                      Steve, Have already tried ether--nothing.

                      Unfortunately, it probably a timing problem. Since the motor has never had the flywheel off, it is most likely the rotary valve gear since that also controls timing. once I get my hands on a "top dead center gauge" I will have a better idea as to my problem. Thanks for your input.

                      Comment


                      • #12
                        You don't need a TDC for that - you can use a screwdriver, or anything else that size - the tolerance is +/- 5 deg, and you can get it more than accurate enough by hand to time the rotary valve. Download the timing guide in the tech section for a walk-through.

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