2 2003 seadoo gti le engine failures

[wakedog]

I have a pair of 2003 seadoo gti le with single carb 717 engine. Each has an sbt standard engine, one was 18 months old and one was 4 years old. Both are completely stock using the oil injection system. Both had been running well and just had the sparkplugs replaced. They were borrowed for a week and was told they just became difficult to start. I wasn't there so I don't know what happened or how they were used.

I took the jetskis home and checked compression. 30psi & 90psi each engine. Below are pictures of the pistons. One had the rings come apart and the other had the piston burn. I am unsure how to proceed with the repairs. I don't want to go to the trouble of an expensive repair not solving the root cause of the failures. Any ideas & assistance would be greatly appreciated.

18 months old


4 years old

 

[XP 787]

A cold start then running wide open without time to warm up can do that. I find it odd that this happened to both motors while borrowed.

 

[mikidymac]

I agree. No good reason for both to blow at the same time.
I see very little piston wash from the pictures so they are probably running lean. When was the fuel system serviced and carbs rebuilt last?

 

[wakedog]

I bought both jetskis in 2012. One had a blown engine which I replaced at the time. Early 2015, it was time to replace the engine on the second. I replaced both carbs in 2012 with brand new carbs but have not done any service on carbs since.

I keep the jetskis at my lake house which is halfway down a no wake zone. So we have to idle out maybe 100 yards out to the lake. Not sure this would constitute a long enough warmup period. Fyi, the marina where I buy gas on the lake only sells ethanol free gas.

Before the borrowing, the jetskis were on the lift (as I hadn't used in a couple of weeks). I replaced all 4 sparkplugs, and ran each for 5-10 minutes. I moored both and left for the borrowers.

Is this a catastrophic failure that happened suddenly or is indicative of a gradual decline. The reason I ask, is both jetskis appeared to be running better than ever all summer long.

 

[Coastiejoe]

Anything is possible, they could have simply failed. BUT,,, I'm with the others. I feeling had something to do with the "borrowers",,,

The real lesson, don't let other use your ski's if you are not there.

In this case, you will never know if it was their fault or pure coincidence.

 

[vcchristensen]

Just out of curiosity, how long is a proper warm up time ? 5 minutes ?

 

[benjilafouine]

My GTI LE 2003 ski usually gets warm in not long, like one minute. When I start it cold, I cannot go to full throttle as the engine doesn't want to accelerate. Then I accelerate gradually for 30 seconds (I can hear it is cold as it misses a few sparks) to one minute and then the ski is ready.

Doesn't take long really.

Are you sure the "borrowers" didn't do anything stupid with them like flipping them and not taking care of them properly?

I never let people borrow my ski. I let family (cousins and nephews) try it within my sight once in a while and only for a few minutes and under strict supervision.

Benji.

 

[wakedog]

Its just they were both running well and trouble free and had no reason to suspect any failure. Lesson learned.

I am grasping at straws. The oil tank was about 1/2 full nearing the point where the oil light would be coming on. Is it possible if regular motor oil was added instead of seadoo xps 2 stroke oil, could that cause this type of failure?

 

[kevinz]

regular motor oil isn't designed to dissolve and mix with fuel, so it's certainly possible. also, you mentioned earlier that they seemed to be running better than ever this summer...I've heard that engines running borderline lean can run like a scalded dog right before they blow. maybe that was an indication that something wasn't quite right.

 

[manolocross]

What kind of oil do you use? If your not using seadoo xps mineral oil in white bottle it's the wrong oil.....

 

[benjilafouine]

Hmmm. Four-stroke oil in a 2-stroke engine would certainly cause trouble. I am pretty sure that four-stroke doesn't burn as well as two-stroke. Four-stroke oil is much thicker. If you siphon a sample from the oil tank you may see that the color is unusual compared to Sea-Doo oil.

I had my engine running "slightly" lean for a while after I rebuilt the engine. It would affect the ski in a way that top speed was a bit lower than previous engine. I opened the screw less than 1/4 turn and suddenly it was going much better. I doubt it would blow two engines in the same week???

I just can't picture why two skis would die at the same time on someone else's watch. Something happened in my opinion. Ski flipped, water ingestion for 24 hours, wrong oil used. Even if they were beaten like hell I can't imagine the odds of two skis dying at the same time.

Benji.

 

[wakedog]

When you say lean, do you mean lean on oil i.e. oil injection failure or lean air/fuel carburetor?

 

[wakedog]

This is the only oil ever used in both jetskis.

 

[mikidymac]

Lean means that the engine isn't getting enough fuel. Like from a plugged carb.

Do you suspect that the wrong oil was used? Filling the tank with standard car oil would defiantly cause a 2 stroke running hard to blow up.

 

[manolocross]

Well although it's is good.... The full synthetic is low ash oil to prevent rave valve excessive maintenance. It is overkill for 720 engine. It cost more. Hmmm....

 

[wakedog]

I have no reason to believe wrong oil or any oil was added. I was just throwing that out because theoretically it could have been done. Just wondering if that would cause this type of damage.

 

[wabash]

Usually broken top rings and lands are due to interference or unusually high compression/detonation. The no wash on the pistons is curious. My take on this would be there was some water ingestion. Are both Pistons on both engines damaged or just the ones shown?

 

[wabash]

And yes running a motor oil instead of 2 stroke oil will do some weird stuff.

 

[benjilafouine]

If it is not the oil, I would think of mistreatment on both skis (like water in engines, and you will never know how they dealt with it when it happened). It is the only way to explain how two skis would give up at the same time.

I spoke to some people who rented skis before: they just don't care about it since it is not theirs. They just beat the hell out of them. One guy told me they even masked a broken impeller by removing the debris without telling the rental people (they actually opened the impeller and cleaned it up before bringing it back). You may just never learn the truth since the persons who used them will never come forward and tell you the whole story.

Rebuild time, and make sure that you replace the oil pump and filter on both skis. Also pay attention to the muffler on both skis as a small hole on them could cause serious issues as per my experience (water ingestion).

Benji.

 

[wakedog]

Below are pic's of the 2nd pistons piston. I did a compression test before disassembly. Each engine read approximately the same 90psi & 30psi (or less). I was using a cheap harbor freight compression gage so the readings may not be entirely accurate.

18 months old


4 yrs old

 

[96spxpos]

yes, lesson learned... Especially on 2 strokes... DO NOT LET PEOPLE BORROW THEM, or even ride them when you are not around or not at all... unless you bought it specifically as a beater and/or know that you'll be doing major repairs soon. and FYI, a WEEK?! that's more than enough time to destroy BOTH of them..When something is not yours, its easy to literally just nail the gas for the entire time you're riding. I dont care how solid of a build your ski is, if a 2 stroke is pinned at full throttle for an hour straight, it CANT be good. My 717 had 148/150 compression and was fogged/taken care of religiously, I was on premix.. and the ONE TIME I let someone ride it, he had his young son on with him, and he was a little too far out to where he couldn't hear me, but I basically watching him for about 30-40 min keeping the throttle in one position where the ski was trying to get up on plane, and just continuing to ride it like that the entire time. he finally got close enough for me to wave him in.. I wave him in, then I told him to back the truck down the ramp while I do a lap and bring it into the dock. I start it, drive about 300 yards, and then crunch..engine blew..

So, moral of the story, they were probably just abused pretty badly.. a week is a LONG TIME.. just out of curiosity, who were these "borrowers"? and, any chance of having them foot the bill?
Hindsight is 20/20 but, lesson learned. you're in the right place though, as the people here on this forum will definitely get you going and up and running again..

 

[96spxpos]

Below are pic's of the 2nd pistons piston. I did a compression test before disassembly. Each engine read approximately the same 90psi & 30psi (or less). I was using a cheap harbor freight compression gage so the readings may not be entirely accurate.

18 months old
View attachment 37271

4 yrs old
View attachment 37272

also, that mag side piston gasket looks to be really loose/stretched... did you pull that off or was it like that when you took off the head cover? Looks like theres some water on top of the piston as well.

 

[mikidymac]

At this point I don't think you will ever know exactly what happened.
From the pictures you can see that at one time there was good piston wash from the markings then they went lean because everything is black with carbon. It could have been abuse, plugged carbs or maybe they had some really old or crappy fuel. Ether way there was not enough fuel/oil and without lubrication and cooling you get a blown top end.

 

[wabash]

This doesn't look like lean burn down at all. 90 psi on the " good " piston is horrible. The pics don't show anything on those Pistons that would produce low comp unless they are just worn. Maybe your test was off. ?? Broken top rings and ring lands are due to water ingestion/coolant leaks. In this case prob coolant leak since it's only one cylinder. I've always been suspicious of SBT as well but a lot of folks have had good luck with them so I can't support any wrong doings there. The coolant leak could be from a warped head which may have been caused by abuse. Or it could be just failed o rings. I don't see any loctite 515 on those o rings so that could be it. Yes it could be abuse but these engines are pretty tough they will take some abuse. I would suggest this. Tear them down with the plan of doing top ends. Split the cases and thoroughly inspect the cranks or have someone knowledgable inspect them. With damage like this to the Pistons the needle bearings in the rod journals may have been damaged. The wrist pin bearings will get replaced with new Pistons so you're good there. Hopefully the cranks are good and you can just do top ends. With that you will take care of all the damage shown in the pics and most likely the cause. It is always a good idea to rebuild the carbs with Oem Mikuni parts as well. You're using good oil. Check out Fullboreonline or PWCengine for top end kits if you don't want SBT parts. If the cranks need replaced or you just want to ( not a bad idea if you're willing to spend the money) you can get good cranks from PWCengine or check with Rick Ritter at Ritter Cycle rittercycle.com. Not 100% sure about Rick and Rotax cranks but he's a good honest guy and if he does them they will be top notch. Have the heads checked for flatness to make sure they aren't warped. Engine shops can do this. OR you could just do a core exchange. SBT again or there's some good ones on eBay. And there's other options as well. Personally I stay away from SBT but that's my preference.