Vibration and then motor lockup - Any suggestions?

[scrisp]

A few weeks ago I got my 96 XP motor running and everything seemed okay when I ran it on the trailer, in the water, all through the rpm range.

I took it out for a test run and <<poof>> motor locked up. When I initially I started it, I was running premix and injection at the same time. I had just replaced the oil lines and cleaned out the tank, so I didn't want to take a chance while the lines were priming.

When I took it off the trailer and started it, it ran fine at first until I jumped on and took off. I was riding really slow, and it developed a vibration as the rpm increased. I thought that maybe it was fouling the plugs and would clear itself after running for a minute at some good rpm. As it hit around 3000 rpm, there was a bit of a pop, like a spark plug came out of the hole and the motor just quit. I jumped off and swam back to shore with it machine in tow. I brought it home and took the plugs out and the motor will still not turn either way, other than just a tiny bit.

Is it possible that something in the jet pump could be causing the motor to not turn, since it's direct driven? I am just trying to look at all possibilities before I pull the motor apart or put the whole thing up for sale. I'd hate to break the motor down and then find that something was lodged in the pump, causing the issue. I've never takena pump apart before and haven't had time yet to really look and see what might be the issue.

 

[OldSchool]

The vibration could be the prop, something partially lodged that eventually stopped it.

Try to get a look, if you didn't see anything in the pump you will need to pull it anyways, then you can see what doesnt spin. Could be pump bearing if it isnt lodged with an object and the engine spins without a shaft.

 

[OldSchool]

Pulling the pump is part of dealing with whatever your problem is, so you might as well start there.

I know a guy who took the information from an experienced rider of a seized engine, that rebuilt an XP800 engine that only had 2 hours on it, only to find a rock lodged in the prop when he went to install it after the rebuild.

 

[Sportster-2001-951C-Stock]

Yep, definitely make sure the pump didn't seize before condeming the engine!

 

[OldSchool]

Yep, definitely make sure the pump didn't seize before condeming the engine!

Especially if vibration preceded it!

Sent from my SPH-L720 using Tapatalk 2

 

[scrisp]

Thanks guys. I need to learn how the pump is removed anyway, so that I maintain my SPX, so this will be a good learning eaxperience.

 

[Coastiejoe]

Anytime you can work on your own ski is a good thing. You will learn much and greatly appreciate the feeling that you KNOW the work was done honestly.

 

[scrisp]

Okay, so I got a few minutes to check the motor out and the pump is not seized, and I was able to get the motor turned over a few times.

When I try to turn it over by hand using the PTO, it's like the motor will "rock" back and forth. I thought it acted as though the connecting rod had come loose on one of the cylinders, as it make a metallic clunking noise at the front of the motor, but it sounded like it was on the starter side. Well, I turned the motor until it stopped, and hit the starter button and it cranked the motor a few times and then stopped again.

I turned the motor back the other way as far as I could by hand (about 20 degrees I'm guessing) and put my finger over the spark plug hole, and cranked it. Both cylinders are moving (I thought maybe only one would if the rod was loose/broken), and seem to be okay.

So I'm wondering, is it possible for the bendix on the starter to engage and seize, holding the motor from turning by hand, except for a few degrees? The Doo sat for 3 years without being started and it looked as though there was a lot of water in the hull for a while, I had to clean the stain out of the hull.

 

[Coastiejoe]

It is not uncommon for a bendix to engage an get stuck.

Easiest way to determine us remove it and see if you can hand crank the engine.

I would think that if it was stuck engaged you would not be able to turn it at all. But as I type this, I woul think you could as the clutch in the bendix would allow so by design.

 

[Sportster-2001-951C-Stock]

Yeah, you might be getting closer. There have been a number of broken bendix sightings where pieces get caught on the flywheel magnets and end up trashing the stator, too. One report was about tearing off the ignition pickup too, others reported lose stator fasteners and corroded stators from trapped water in the stator housing. Don't recall which engines exactly, just they were rotary valve motors.

Wonder why it was abandoned for a few years, just loss of love?

 

[scrisp]

The girl who owned it went away to college and then had a kid and she just lost interest in it.

How hard is it to remove the starter? I have the manual, but it makes everything look/sound easy. lol

 

[northshorerider]

Why not try pulling the head and taking a look at the pistons as the head uses o-rings so there is no gasket to replace. Easy job only takes about 30 min.

 

[Crofoot50]

The girl who owned it went away to college and then had a kid and she just lost interest in it.

How hard is it to remove the starter? I have the manual, but it makes everything look/sound easy. lol

3 bolts ,2 up front and one rear, disconnect pos cable it pops right out . Easy

 

[scrisp]

Well, it's been a while since I did anything to my '96 XP, I just winterized it and left it until this past weekend. It was really nice Friday night and I was determined to try to find out what the issue was, which I did, to my dismay.

When I put the carbs back on last summer, I was putting the airbox back on and dropped one of the little hex bolts inot the hull, or so I thought. Someone was talking to me when I was working, which I hate, and the bolt actually went down through the carb and was probably sitting on top of the rotary valve. When I fired it up, it was probably jumping around like popcorn in there until it caught just right and messed up the rotary valve and sucked into the engine. I took the carbs and roatary valve cover off, to inpsect the damage. Nothing that I can't repair there, but the motor spins freely for one full revolution and then there is a definite metal to metal contact. It spins back the other way freely also, for one spin. The bolt is in the lower end somewhere, maybe "welded" to the crank or rod, which is why it spins for a little bit.

Not sure if I'll get lucky and it will just be sitting in the crankcase or if I'll have to have it rebuilt. The rest of the motor had excellent compression, good oil flow, and it ran really well with the rebuilt carbs, until this issue.

Anyone know about how much a lower end would be, or does someone rebuild just the lower? I thought about getting a rebuilt motor from Full Bore, and making life easier, but if I can get just the lower, I might be better off going that way. I sold the trailer last summer for $300, so I'm only into the Doo for $200 right now and with a new motor, it would be about $1300 that I'm into it for. I replaced the fuel and oil lines last summer, cleaned both tanks out, and repaired the VTS, so it seems like the hardest stuff is already done.

 

[KyleB]

from what I understand from reading your posts you may try pulling the jugs to see if you can get to the bolt. Also, pull the carbs and see if the bolt is stuck in the rotary valve. Last year I had a weird thing happen and when it did I was thinking that it was a once in a life time thing but listening to your story you may have the same issue. The side of the mag RAVE sheared off and the little piece of aluminum dropped into the mag cylinder. It wedged between the top of the piston and the exhaust port. The engine would not turn over obviously and I didn't know what my problem was until I pulled the head. I removed the piece and the she would turn over fine. I would up pulling the jugs just to make sure none fell down into the crank. Sure enough I found a small piece in the bottom. I replaced the broken RAVE and reassembled everything. I have not had a problem since. I hope I have given you some ideas to get your machine back on the water. BTW I got mine rebuilt a couple of years ago at Full Bore and could not have been more pleased if that;s the route you choose to go. Good luck. :cheers:

 

[scrisp]

I haven't taken the head off yet, I kinda forgot about doing that over the winter. lol I might do it tonight though. Hopefully, I'll get really really lucky, and the bolt will be on top of the piston, instead of down inside the crankcase, doing more damage. I just saw the damage to the rotary valve, and figured that it probably went down inside.

Whatever I decide, I just picked up a crack free, purple tuned pipe and waterbox a few minutes ago for $40, Going to pick it up tonight, mine has a crack in it.

I have some friends who live really close to Full Bore, so I'll save shipping costs when I go up there to visit. Heard nothing but good stuff about them.

Thanks for the reminder about the jugs, and some ideas.

 

[KyleB]

I haven't taken the head off yet, I kinda forgot about doing that over the winter. lol I might do it tonight though. Hopefully, I'll get really really lucky, and the bolt will be on top of the piston, instead of down inside the crankcase, doing more damage. I just saw the damage to the rotary valve, and figured that it probably went down inside.

Whatever I decide, I just picked up a crack free, purple tuned pipe and waterbox a few minutes ago for $40, Going to pick it up tonight, mine has a crack in it.

I have some friends who live really close to Full Bore, so I'll save shipping costs when I go up there to visit. Heard nothing but good stuff about them.

Thanks for the reminder about the jugs, and some ideas.

Make sure you follow the tightening torques and pattern when you put the head back on. If you do happen to go inside the crank take a magnet and fish around down there and unless the bolts have replaced with stainless you can find it. In my case I have a really powerful light and found the piece of aluminum and just fished it out with some flexible grabbers. There is not really a who lot of oil down there so it should be fairly easy. Good luck. :cheers:

 

[Mekanix]

Sounds like the counterballance shaft could have a seized bearing. Hence the vibration before it locked up.

 

[scrisp]

I got the cylinder head off and no luck on finding the bolt in the cylinder. But, while i was taking the bolts out, one of them broke off in the jug. Can a seized head bolt be taken out of the aluminum, or is that pretty much the kiss of death for the jug? It broke about 1/4" below the edge, so there is no way to get vise grips on it, or anything like that. I;d hate to have to replace that entire section if I don't have to, as the compression was almost like new, 149 on the PTO cylinder.

Hopefully, I'll get the jugs off this weekend and see if I can find and remove the bolt from the lower end, well that is, if it's even a bolt. I'm still not positive that is what happened, but pretty much sure. The motor rotates nice and smooth by hand, until the rear connecting rod goes all the way down.

I just picked up an entire exhaust system that looks almost new, from the manifold to the waterbox, for $40 off Craigslist. My pipe was corroded and leaking, so I'm making progress at least.