Blown Motor 587 White Case Rear Cylinder

[Joe Snuffy]

Hello,
I was reading on your forums that a lot of Sea Doos engine failure happens on the rear cylinder as mine did. The rod broke off near (needle bearings closest to crank) the needle bearings leaving the part which goes around the needle bearings in place and leaving a gap where the top of the rod use to connect to it. At that point it put a hole in the side of the cases, did damage to the cylinder sleeve, and destroyed the bottom of the piston. My question is based on what I read that most engine failures are caused because of a bolted on component other than the engine. Both cylinders looked to be shinny with no signs of oil starvation on them. I have 1 carberator on the engine so I don't think it was the back cylinder being to lean. I think it might have been the oil pump which I am eliminating and going to pre mixed fuel after rebuild. Any guidance and knowledge would be greatly appreciated.

[ February 17, 2004, 08:28 PM: Message edited by: Joe Snuffy ]

[stevepaulus]

IMO, if it was the oil pump......both cylinders would show signs.

Shinny....as in washed clean...pics would be nice.

Could have been sveral things, need a description of what the pistons look like...vertical grooves, scoring.

Like i said, pics would be nice if you can get some posted.

[Bill O'Neal]

Most of the rod failures are caused by water or condensation being present inside of the motor and the resulting rust that accumilates on the rod bearings. These engines will run for awhile until the rust pitting causes the bearings to overheat and then come apart, breaking the rod.

The reason that it was the rear rod that broke is because everytime you shut that motor off, the rear piston was in the down position, uncovering the exhaust port. When the exhaust port is uncovered, there is noting to stop the condensation from the muffler to travel back up the pipe and settle in the rear cases.

Using fogging oil after each ride will greatly reduce the chances of getting a rusty crankshaft and a costly rebuild. One element of fogging oil is a water dispersent and the protective coating that it leaves on the metal parts.

I would guess that you did not fog your motor regularily after riding your ski?

If the oil pump failed, both pistons would have siezed long before the crankshaft took a dump.

[ February 18, 2004, 08:40 AM: Message edited by: Bill O'Neal ]

[Joe Snuffy]

Bill,
Thanks; I purchased the ski with the blown motor and based off what you said it makes since that the condensation/surface pitting on the rear portion of the crank had occured. The motor had very low hours as-far-as I could tell by looking at it the paint which was original and still bright white with not much signs off built up oil on it. The inside of the motor also looked very much like new such as cylinder walls, wear on wrist pins, the good side of engine on both ends of rod looked like new, oil build up/depoists in case halves was also very nominal. When I placed the old rings back into the cylinder to check the gap it was pretty small around 10 thousants I would guess. I will purchase fogging oil and use it regularly on all my water toys, Thanks for the tip and help.
ps I don't think sending pics would help in this situation the cylinder walls were in very good shape as-well-as the good piston the tore up piston was in good shape also for what was left of it neither had scaring from oil starvation. The good piston can be viewed however on ebay I am selling it item number 2986692228.

[Bill O'Neal2]

Now all you need to do is call Ericka at SBT and order another motor!

[Joe Snuffy]

Bill,

Like Ihave heard others say I wish I had found this place sooner. I have almost completed re-building my blown engine. It doesn't have any guarantees and the crankshaft I put in it is questionable at best. On a positive note I almost have everything I need to complete a good core minus the cylinders which I think I will have soon (within 2 weeks). I will then order a motor from you/SBT and put it up for later this summer because I have a sick feeling that the one I built might not even make it through the summer or I will be riding around waiting for it to fly apart or get me stranded somewhere. If I could give anyone LESSONS LEARNED that is reading this I will have more money in the questionable motor as I could have purchased a guarenteed motor from SBT not to mention all the positive comments I have heard from other skiers on this forum who have a SBT Motor in their ski. When I got into building my blown motor everything just kept snowballing meaning I needed this widget to fix that widget and they all are expensive widgets. This site is awesome I am telling all my friends about it and any jet skier I see on the lake it will give them piece of mind, save them money, and give them a realistic learned by trial and error knowledgeable opinion.

Thanks
Joe

[ February 19, 2004, 05:28 PM: Message edited by: Joe Snuffy ]

[Bill O'Neal]

Joe,
Yes I find it difficult to rebuild a motor in my shop and save money over just picking up the phone and calling SBT and ordering one, plus they give the best warranty in the business.