Oil on spark plug in Cylinder 1 (215 HP SCIC)

[dootndo2]

The motor is backfiring at 5000 RPMs. Not 4500 or 5500, but right around 5000 RPMs. It was reproducible numerous times (by tech). The boat was taken back to the shop to determine there was a fouled plug. The plugs were changed out and the boat water tested again. Still backfiring. The techs then looked at the new plugs and determined that there is oil on the plug in Cylinder 1.

At this point, they can't definitively say what is wrong with the motor without taking off the headers. They said that it is likely a valve seal leak or a cracked piston ring, but who knows. But it could be a scratch on the cylinder wall or a problem with the piston.

Other things to note is that the compression on Cylinder 1 looks normal and the boat runs normal (with the exception of the backfiring at 5000). I never drive the boat at 5000 RPMs because it generally hasn't cleared plane well enough to be manuverable. I usually idle around up to 3000 RPMs, use full throttle to get out of the hole and then generally cruise between 6000-6500 RPMs. It is very possible that it has always backfired and I just didn't notice it. So I plan to take it out and drive it to see if I can tell that there is a speed improvement and/or if there is a backfiring issue.

The boat has 112 hours on it and I'm concerned in two ways.

1. Not fixing it and having some type of major failure while on the water.
2. Dropping another $1500 to find out that they still can't figure out what the issue is.

I have met with another close by dealer and am working on building a case with Seadoo for their help/support. I really love the boat, but I don't want to have to drop $1500 in maintenance a year for this thing. It's just crazy.

I'm looking for ideas, suggestions, feedback, or experiences in dealing with Mother Seadoo (the company) to get these issues resolved.

Here is the history here:
http://www.jetboating.net/jetboating/common/forums/threadview.aspx?forumid=1&page=1&threadid=15581

And as always, thanks!

dootndo2

 

[dootndo2]

The motor is backfiring at 5000 RPMs. Not 4500 or 5500, but right around 5000 RPMs. It was reproducible numerous times (by tech). The boat was taken back to the shop to determine there was a fouled plug. The plugs were changed out and the boat water tested again. Still backfiring. The techs then looked at the new plugs and determined that there is oil on the plug in Cylinder 1.

At this point, they can't definitively say what is wrong with the motor without taking off the headers. They said that it is likely a valve seal leak or a cracked piston ring, but who knows. But it could be a scratch on the cylinder wall or a problem with the piston.

Other things to note is that the compression on Cylinder 1 looks normal and the boat runs normal (with the exception of the backfiring at 5000). I never drive the boat at 5000 RPMs because it generally hasn't cleared plane well enough to be manuverable. I usually idle around up to 3000 RPMs, use full throttle to get out of the hole and then generally cruise between 6000-6500 RPMs. It is very possible that it has always backfired and I just didn't notice it. So I plan to take it out and drive it to see if I can tell that there is a speed improvement and/or if there is a backfiring issue.

The boat has 112 hours on it and I'm concerned in two ways.

1. Not fixing it and having some type of major failure while on the water.
2. Dropping another $1500 to find out that they still can't figure out what the issue is.

I have met with another close by dealer and am working on building a case with Seadoo for their help/support. I really love the boat, but I don't want to have to drop $1500 in maintenance a year for this thing. It's just crazy.

I'm looking for ideas, suggestions, feedback, or experiences in dealing with Mother Seadoo (the company) to get these issues resolved.

Here is the history here:
http://www.jetboating.net/jetboating/common/forums/threadview.aspx?forumid=1&page=1&threadid=15581

And as always, thanks!

dootndo2

Any thoughts on this? Thanks in advance.

 

[seadoosnipe]

I think your totally right... I don't want to sound like I'm not concerned, but like you said, has it been there the entire time you've been running it? Why I say that is cause I'm the first one to say when I'm out, I have to listen so intently to the motor, all the time to see if I'm hearing something I shouldn't. Not just the boat or ski, but my motorcycle too (I no longer have the bike though). It's like trying to hear or find something, that might not even exist.

But, like you said, I would def hate to not look into it, then have major engine damage down the road. These supercharged motors are super powerfull. They do not like to work at low rpms. As you increase throttle, you increase boost off the supercharger. Over time, parts begin to wear. So, the boost you had at 5000 rpms a few years ago, may not be the same now. Of course, with all the sensors, adjustments are suppose to be made to keep the fuel/air systems running efficiently during operation. But, I sometimes have problems believing all that stuff works exactly like it's said to.

The motor is suppose to take care of itself. I don't know if you have to worry about a major problem because the engine managment system should warn you before you reach the "critical" stage. I dont' have the $1500 bucks to spend, just to get the answer that I don't want to hear. "I'm sorry, but we still can't find a problem"... But, they are going to keep your money.

If you've done compression tests and they are all good, no obvious leaking of fluids and the motor sounds to be running well at other speeds, then I don't know if I'd make a fuss over it. The way you describe it, at an exact rpm, makes you wonder if there is some sweet spot where the engines management system is in between adjusting for proper fuel/air flow, just enough to cause a slight miss.

There is really no "miracle" answer for your question. And I'd have to be there to understand exactly how important the problem sounds, but from your description, it doesn't sound to be a real major problem. No codes?.. Or any other problems but from what you hear, or feel. Of course, if you are persistant to a repair facility that there is a problem, I'm sure they'll dream one up for you, to get that money. Oil on a plug, or in a cylinder.......yeah, right. There is oil on the walls of all three cylinders.