97 XP piston seized. What to do? (pics)

Note: This site contains eBay affiliate links for which SeaDooForum.com may be compensated
Status
Not open for further replies.

homerson

Member
I have a 1997 Sea Doo XP. I bought this ski used, in June and have run it for about 10 hours. One trip out it started having reduced performance and could sputtered around. I read about the crappy default fuel lines so I decided to replace them hoping this would fix the issue. I also put on a carb primer kit, and cleaned out the carbs a bit, they were not bad but had a little gunk in them. The next trip out it started out well and was doing quite well for an hour or so, then is suddenly lost power, stuttered a bit and then died. Trying to start it I just got a click.
So that was the end of that day on the lake. I took apart the drive shaft in the back and looked to see if a bearing had seized, no it looked like it could use a little more grease but otherwise wise was fine. I took off the top end and saw the problem immediately. The second piston had some shards on the top of the piston and you could see it was very dry in there. It was running lean in that cylinder for sure, the other one looked ok.

You can see in the pictures one cylinder looks ok in that it has oil in it the other is dry and the top fo the piston looks scared up. The head also has pitting. I'm trying to figure out how this happened? What could cause one cylinder to not get oil? When oil injection fails does it usually do so only in one cylinder? I'm assuming the best approach here is to rebuild the top end, and flush the crank case incase any other shards got down in there. Would you all agree?

IMG_1464.jpgIMG_1465.jpgIMG_1466.jpgIMG_1467.jpgIMG_1469.jpg

Also I looked in the manual and I can not find the part in the image below. I removed the cap and oil shot out. It looks like an after market thing but no clue what it is for.
 
IMG_1471.jpg

Above is the part I was talking about. What is this for? It comes from the oil filter to the bottom of the engine.
 
IMG_1473.jpgIMG_1476.jpg

Above is the largest 'chunk' that we found in the cylinder. IT was on top of the piston and is not magnetic any ideas where it could have come from?
 
Last edited by a moderator:
Actually, for clarification, the last piece is metal, but its aluminum. Cast aluminum to be exact, but its not a piece of the piston, as it looks to have had a point at one time, like the end of a gear or something. We pulled the valves on the top of the cylinder, looked all around, and I can't see anything that broke off anywhere.....

I am friends with homerson, and we worked on this together tonight....

Any help or opinions are greatly appreciated.
 
Hi Shane! My fist guess would be that you are looking at a piece of piston. Possibly part of a skirt, or worse if something got caught in the block & broke something away there? You might as well tear it down & see what you have. In a two stroke the bottom half needs to be as clean, or cleaner than the top half, so most of what you are seeing came from the basement of your engine first. In other words, its probably going to be a mess down there.... IMO, anytime the top end fails, its important to pull the engine & split the block. then you can inspect & clean everything. Even if it doesn't need it, it doesn't cost much more. Just a couple extra seals & gaskets. However, if you find more things in the case (and I am guessing you will) that will save all your money spent on repairing the top end. I have some pictures of an engine I rebuilt 6 years ago, were only the top piston ring land broke off & appeared to go out the exhaust. Very little damage upon initial inspection. Split the block & it was disgustingly dirty. Small fragments that would have destroyed the rebuild and possibly the bearings If I would have left it. Been tearing them all apart after seeing that.
 
it looks like someone has removed the line to the rotary valve oil bath and added that fitting to add oil if needed. do you have two lines coming from the bottom of the oil tank, and another that runs up to the top near the cap? the line with the filter on it should go to your oil pump at the front of the engine. assuming the oil pump is getting oil, and the coupler between it and the flywheel is fine, and the oil pump is working, the only way for one cylinder to not get oil while the other does, is if the oil line from the pump failed/cracked/fell off, or if the check valve that keeps the pump from sucking air back into the line failed. my bet is that the oil line fell off or broke on that cylinder, which caused your oil starvation. OR, previous owner removed the oil system and didn't tell you to premix....
 
I's do not believe that is oil starvation. Am I correct that that motor has 2 carbs? My guess is that cylinder 2 was running lean and that caused the failure.
 
it is a two carb system, and the plug does indicate a lean environment in that Cylinder. We have inspected the oil lines and they have not fallen off.

My goal is to number one fix it, which sounds like pulling the motor (ugh) and number two keep it from happening again, which vdubn suggested going to premix and bypassing the oil injection all together.

What would one expect a repair like this to cost at a shop?
 
it looks like someone has removed the line to the rotary valve oil bath and added that fitting to add oil if needed. do you have two lines coming from the bottom of the oil tank, and another that runs up to the top near the cap?

What is odd about this cap is it has a hose like fitting like you would attach something to it, it comes in after the oil filter and when we first opened it oil shot out of it. Now that the engine has seized the line is empty of oil. Why would you add oil in at this fitting instead of the oil tank? I've called the previous owner to ask but no reply yet.
 
It doesnt make alot of sense to bypass the oil tank for the rotary valve and still have the oil pump hooked up.

If you dont know the condition of the crank I IMPLORE you to at least fully disassemble, clean, and check the crank.

Things come apart for the darnest reasons...I had a cyl chip a chunk of the bottom ring off and wrecked the piston and head...but somehow there is no corresponding mark on the port/cyl.
 
I do plan to take the entire head off, get a good look at it and yes the smartest thing is to flush the crank and really look at it. Just not sure I have the time to get it all done before the next camping trip. Thus wondering if a shop would be a better road, but not sure how long it should take and they are looking at charging 90$ an hour.. yikes!
 
Buy an sbt rebuild,and fix the lean condition or it will happen again. There is no one on this forum that will agree to a half azzed repair. Do it right or don't bother doing it at all. This failure could have been avoided if the carbs were properly rebuilt.
 
Last edited by a moderator:
When we put in the carb primer kit we did take them off and clean out a little gunk from the eroding fuel lines. When you say "properly rebuilt" the carbs what do you mean? They did not look bad, such that they warranted being replaced or rebuilt. It is possible we did something wrong when taking them off and putting them back on, but how would one know or tell?
 
Last edited by a moderator:
properly rebuilt, meaning they were taken apart, cleaned, inspected, and had any worn or damaged parts replaced. then set up to factory settings before being reinstalled.
 
SES is cheaper than SBT, but will take longer to get your engine done.

Yea, do rebuild the whole engine, else you will be doing this all over when that crank goes.
 
SES http://seadooengineshop.com
SBT http://www.shopsbt.com/

Before you buy an engine, why don't you consider pulling the engine apart & see what you have? They are really not that complex depending on your abilities. Just have to pay attention to details & assemble it according to the service manual (available online) The problem with just doing the top end, is left over & hidden debris in the case. Not cleaning it out, would be the same as dropping metal debris down the carb after its back together. Unlike a 4 stroke engine where debris in the crankcase just settles to the bottom, the 2 stroke engine uses the crank case as part of the combustion process. You don't want anything in there, period. Just my $.02
 
We removed the carbs and carefully disassembled them to inspect for grey hose pieces that might have come through the carbs. There was some sediment, but no chunks of fuel line. The ski only had about 80 hours on it, but had been stored for 7 years without use. So, we just reassembled exactly how it came apart, no changes to anything. We blew them both out with carb cleaner, and replaced the grey fuel lines with std black fuel hoses, and installed the primer kit... that is it.

Normally I would agree that the one cylinder might have been fuel lean (but I think it stopped flowing oil). The electrode and insulator were not a super light color, and the ski had excellent power. If one cylinder were lean enough to cause the issues, I would think that you would notice it in the performance immediately (it ran perfectly for over an hour). The engine wasn't hot, there was no bog through the power range, and it never fell on its face when opening it up on the top end (all tell-tale signs of it running lean). Maybe there is enough power in one cylinder to make you feel like its running perfect, but I know in my 2 stroke 2 cylinder Banshee's, if one cylinder was lean, you felt it, and the bike didn't perform at all to its potential.

The oil cap that Shane posted, had me really wondering... is this just 2 stroke oil that is circulated through the rotary valve? If so, there was a huge gap/air bubble in the line from when we accidentally pulled that cap off. When we did that, oil shot straight up and all over both of us and the side of the ski (not running). Since then, there has been air in that center section... could that have caused the pump to push air into the oil lines, thus starving it of oil? Still not sure what the purpose of that cap is, maybe to add oil until there is no air in the system? Could it be essentially a bleed mechanism, since its at the highest point in that circuit?
 
I agree on the engine build, we will tear it down completely, and make sure that the crank is inspected for debris, as well as the seal that can cause the crankcase to fill with oil. At such low hours, hopefully the crank is still in good shape.
 
Did you clean the small filter in the carb? That is the problem with dual carb set-ups, the good running cylinder can mask the poor running cylinder and the rider may even be unaware that a problem exists, meanwhile a cylinder gets cooked.
 
Last edited by a moderator:
I just went through and did what you guys did with replacing the fuel lines and cleaning the carbs and carb filters, you would know if you cleaned them, mine had some junk in them, cleaned rave valves as they where pretty bad, would like to know what caused this as well as I dont want to go through what you guys are, man what a bummer.
 
It was like my 5th time out this season after buying it, a big bummer, but I'm learning a lot and have good friends to help me figure it out. I'll keep this thread updated with what we find out and more pictures of the carb filter once we get it apart.
 
well we got it apart and it was not a pretty sight. as you can see from the pictures, bottom of the piston skirt blew up, and the piston rod is bent, the case cracked.. I now own a bunch of scrap metal...

We got the carb apart and the filters had some gunk in them but they did not cause this. Vdubn is thinking water in the engine is the likely cause. Any other ideas?

Guess I'm in the market for a new 787 engine.. /sigh
send me links for a good replacement :)

IMG_1486.jpgIMG_1487.jpgIMG_1489.jpgIMG_1490.jpgIMG_1492.jpg
 
Status
Not open for further replies.
Back
Top