New Motor Lasted 15 Minutes

[deanler]

Just redid the motor in my 93xp and about 15 minutes out on the water the thing died and now only turns over slowly...

I believe it is crank related again. I did everything to prevent this from happening again, cleaned carbs, filters, 32:1 premix... WHAT GIVES?

Plugs look good other than being rich from oil and I didn't even take the thing over 4000 rpm trying to break it in...This is my first seadoo and so far I am not impressed with the sport hahaha.... I'm going to tear into it tommorow but right now I just can't understand how this would even happen at 32:1

 

[6KJR]

Could be the type of pistons you used, depends on a lot. When you tear it apart take pics of any engine damage. Usually you can tell by scoring and piston marks what caused the engine failure.

 

[Dr Honda]

OK... you changed to pre mix... but did you leave the oil tank in the hull to feed the rotary valve gears?


Also... what kind of oil are you using?

when you put the engine back together... did you do a leak down to see if there were any leaks? did you properly set the squash band?

Until we know what happened, it's hard to say what happened.

 

[deanler]

Could be the type of pistons you used, depends on a lot. When you tear it apart take pics of any engine damage. Usually you can tell by scoring and piston marks what caused the engine failure.

I used WSM platinum pistons and I'll be sure to take some pictures when I pull the top end today, Thanks!

 

[deanler]

OK... you changed to pre mix... but did you leave the oil tank in the hull to feed the rotary valve gears?


Also... what kind of oil are you using?

when you put the engine back together... did you do a leak down to see if there were any leaks? did you properly set the squash band?

Until we know what happened, it's hard to say what happened.

Yes I left the oil tank in about half full feeding the rotary valve with seadoo mineral oil and the gas was mixed with that and seadoo synthetic oil aswell...

Didn't do a leakdown test and didn't check squish but would squish it really be an issue with original parts? I'll check it I guess when I put the motor back together again for the 2 minutes it takes.

I don't think It's top end, I took out both the plugs and trying to turn it over by hand is really stiff, I turned it over about a full turn and it sounded like a rod clanked off of something inside...

I'll see if I can rip the top end off it today and post some pictures, hopefully I can benifet from some of you guys' experience

 

[olds72]

The leakdown test is a must do after a rebuild.

 

[Dr Honda]

Yes I left the oil tank in about half full feeding the rotary valve with seadoo mineral oil and the gas was mixed with that and seadoo synthetic oil aswell.

GOOD about the gears. This year we've see this as a problem at least a dozen times. BUT, BAD because SeaDoo mineral and synthetic don't mix well. You can mix it with the new Synth blend oil, but not the regular synthetic.

Didn't do a leakdown test and didn't check squish but would squish it really be an issue with original parts? I'll check it I guess when I put the motor back together again for the 2 minutes it takes.

BAD.

OK... you lost a top end, and that's obvious since you did a rebuild. BUT, a bad crank seal, or an air leak in the case can look like loss of oil, or a lean run. A leak down is the #1 thing to check after needing a top end.

Also... no, you wouldn't have to check the squash band if you were using the same parts over again. But, you weren't even using stock parts. You were using WSM pistons. Even if you replaced them with FACTORY SeaDoo pistons... there are variances in production. That's why they make 8 different base gaskets. In a SeaDoo engine, it's critical. For all you know... the pistons could have been hitting the head, and that would have cause the rod bearings to fail.

I don't think It's top end, I took out both the plugs and trying to turn it over by hand is really stiff, I turned it over about a full turn and it sounded like a rod clanked off of something inside...

I'll see if I can rip the top end off it today and post some pictures, hopefully I can benifet from some of you guys' experience

Please do. I'd like to see what happed.


Sorry for the loss.

 

[deanler]

Well I figured out what my issue is and have some pics.

First heres a pic of the machine under the knife, I know not really relevant haha

Heres the gear on the crank, shifted to the right and putting pressure up against the bearing.. hence why it was stiff to turn over

Brass gear on rotary shaft missing a tooth

Shavings in the bottom half of the case

Now heres what caused it.. The cast aluminum piece that the plastic air box bolts to is held to the carbs with 6 bolts... well there was only 5 bolts when i took it apart and when the carbs came off the bolt fell out.. bolt must have made its way down pinched the rotary valve and went back up into the carb??

Pistons and bores are good to go.. rotary valve surfaces are both good just have to clean a burr off the one.. Looks like i need a new crank unless I can heat that gear and slide it over or something..but that bearings probably screwed anyway

Suggestions?

 

[6KJR]

Ouch, that really sucks.. Well when that rotary vavle jammed it probably did that damange to the internals. I think you can just get new bearings for your crank. I know some are replaceable on some cranks. we used to just use temperature changes for sliding on and off the bearings. IE.. Cold crank, warm up the bearing gently and it should slide on. (even used this trick for getting pressed pullies off superchargers on cars) threw the pulley in the oven for a few minutes, slides on. Just dont go overkill.. And yes, that is the redneck way. But I dont think its worth replacing the entire crank for that. Unless you have to. But what the heck do I know..

 

[k.trojcak]

that happend to me the day after I bought two 94 spx's. now all bolts have loctite so it can't happen again

 

[deanler]

Alright so far my options are an SBT crank or a used OEM crank I found...sbt 225 or OEM for 180.. He said everything is good and tight but it almost looks like rust on the bearings.. I would hate to spend 180 only to have to spend another 225 and then I might as well got a "good" one. Heres a picture of the used one. Hoping to be back on the water by this weekend

This is a 657x crank and I have the non-X motor from my understanding its the same crank just the design is a little different