Announcement

Collapse
No announcement yet.

back piston blown apart

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • back piston blown apart

    What would cause the back piston to blow apart?
    It is a 580 white engine the year is 95. My friend was riding and it made a load pop then started losing power. Got half way back to the dock and then it stopped. The front piston looks good except for the extra metal in it from the back piston. He is going to order a rebluid engine but is there another problem we should look for before installing the new one? any help would be nice. thanks jkool

  • #2
    oil pump or premix?

    Did it ingest water?

    How are the carbs, have they been rebuilt and cleaned since he has had it?

    Comment


    • #3
      oil pump, Don't think it had water in it but I didn't flush all the time for him he did once in awhile but it run for about 4 hours that day it died. He didn't redo the carbs but the guy before him did. It was getting oil because the tank was half full and we filled the day. But that doesn't mean the back was getting the oil. He did get alot of weeds in the prop so I thought he fried the crank.

      Comment


      • #4
        seperate the drive shaft from the engine........see if the driveshaft spins with ease disconnected from the engine. How much metal we talking? I have never seen a piston just blow apart, they usually just lock up. Does the rear piston move, could of snapped the rod.........ya really need to tear it down and inspect the lower half also.

        Comment


        • #5
          the shaft spins fine the engine is out and broken down in the lower half the back rod is locked up the front looks great. the bottom half of the piston is gone makes a good ash tray though. I thought the bottom froze and cocked the piston a little and it hit the bottom case but it sounds odd though.Its all apart and ready for swap but I was wondering if its because of oil maybe we should block it and go with pre-mix but I think the oil pump is fairly new 2 or 3 years old. Who knows what the other guy really did to the ski he sent it to the dealer all the time.

          Comment


          • #6
            In my honest opinion......if you don't know what he did to it, block the pump, rebuild the carbs and make sure there is no blockage in any of your fuel or water lines.. If the driveshaft spins on the pump, it's not the pump.

            Comment


            • #7
              One last question, is that a single or dual carb, and how many turns out are they if it's dual(the low speed and high speed circuits)?

              Comment


              • #8
                Its a dual carb but to be honest I have no idea how many turns out it is it ran and if it runs we don't play with them at all untill we have to rebuild the engine btu we are use to kaw 550 and 440 so they are pretty basic to play with. We have had them since 76 the one 440 is and 78 and 86 550 they are just more fun but the sit down are good for relaxing to use. I have to look into rebluiding the carbs and blocking the oil maybe it will be easier and safer. But the ski ran great all summer just fowled the plugs if the kids started it. A least my gp800 runs good.

                Comment


                • #9
                  95......what moedel sea_doo?

                  Comment


                  • #10
                    How long did ir run before it took a crap, and did was this just today? Did it run ok in the past?

                    Comment


                    • #11
                      what do you run for oil? have you mixed brands? i have found in my shop people who have added different brands of oil, the oil is not always compatable, and a chemical reaction can occur,and the oil will gel (especially with seadoo mixed with other brands.) how does the bottom rod bearing look? if it is a lack of oil problem the rod will be bule looking and brings cooked from lack of lube. these are the first to get oil in your motor. i have seen many busted pistons from age, fatique,abuse, too much tolerance, cheap pistons ect. again its hard to say with out actually seeing the motor. i would definatly remove the oil inj. good luck with your doo. zig
                      please visit my link with pics of my many parts for sale

                      http://pg.photos.yahoo.com/ph/radracingpics/my_photos

                      email radracingpwc@aol.com

                      Comment


                      • #12
                        The lack of oil did not cause this problem.

                        What breaks piston skirts is usually either crappy pistons, or lots of piston to clyinder wall clearances, when the rod is still intact.
                        Bill O'Neal WCM
                        <a href="http://www.watercraftmagic.com" target="_blank">www.watercraftmagic.com</a>

                        Comment


                        • #13
                          I think the clearance might be the problem.The rods still look good but the back got a little metal in it and froze. we were going to redo the top end at end of season because we thoght the rings might be bad. But a little too late in this case. The plugs were getting real wet and hard to start had to keep changing them or drying them with the old lighter trick. I guess we should go and order the new engine. Hopefully it's a good core with the semi pitted head and cylinders. Thanks for the info guys.

                          Comment

                          Working...
                          X