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I have a friend that has a 2010 xp850 sportsman and he swamped it out last weekend while IDILING across a stream. He IMMEDIATLY shut if off, brought it home changed the oil, tilted it back to drain the water out of the exhaust, and pulled the spark plugs. He spun the starter over to blow the water out of the spark plug holes and after it spun over several times it locked up w/ the plugs out? He took it to the dealership this weekend and the mechanic said he has had several XP850 in the shop that customers had done the exact same thing to and it breaks a piston every time!!! The mechanic said you cant do these XP's like you could the other machines and simply change the oil and pull the spark plugs out and go. He even let my buddy stay in the shop w/ him and showed my buddy a chunk of the broken piston in his motor while he was there. He told him if you follow the proper procedure for "deswamping" these XP's there is no damage. (only $85.00 at the dealer to do it). My wife has a 2012 XP850 and I would like to know if anyone knows this "proper procedure" in the event the same thing happens to her's? I know one of the things he should have done is drain the runners that lead off the left side of the air box, but I dont know of anything else. I was hoping some one could shed some light on this.
Thanks.
 

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I would have done the same thing ur buddy did. That is how to do it on a c twin....maybe the parallel twin is different??


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Well I'm stumped myself. I thought he did it the correct way. Can't wait to find the "correct" way. I'm subscribed
 

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I think the mechanic is bs'ing you. That is the proper way.

Your buddy must not have shut it off right away if he hydrolocked it and broke shit internally. Usually hydrolocked motors bend rods, not break pistons.

Have any pics of the motor pulled apart, and the broken piston?
 

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Discussion Starter #5
I think we have had 12 or 13 Sportsman's and 3 RZR's in my family over the years, and thats how we have always did it too??? I feel bad because I'm the one that told him to do it that way. I'll see if he has any pics on his phone. I'm planing on going w/ him to pick it up next week and see if I can get the 411 on the "proper procedure". It really only ran at an idle for a split second and he shut it off when i went under water??? I'm stumped because I just can see that hurting it. When we get it back I'll make a post.
 

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did he crank it over with no oil in it? not that that would break a piston, just curious.

as others have said, seems like the correct way to do it, im sure he hydro-locked it, and somehow the piston was the weak point
 

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I wonder if turning it over with the drain plug out would get more water out?
So have the plugs out and drain plug out and just jog the starter a few times. Maybe if there was still some water it would help keep pressure down?

Was he sure all the water was out of the intake system?

Tilting it back to drain the engine out of the exhaust only works in the exhaust valves are open.

If it is a cracked piston it could be from the water getting into the intake and then into the engine and the extreme temperature difference would cause the piston to crack. I did that on a jetski once.
 

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Nothing against your friend, he thinks he shut it right off, but even at 1600 RPM, the crank will spin 26-27 times a second, so it might not have shut down fast enough to avoid damage. What he did to drain it sounds like the correct procedure, but I think the damage was already done.
 

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Without a plug in it, even with water in the engine you would not break a piston. There is no compression and as long as the oil was changed and drained its not like there would be water under the piston anymore either.

I would stand on end and drain the airbox and muffler, drain the oil and change, pull the plugs and turn it over a few times. How else could you possible do it?
 

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If the piston cracked it was while the engine was running and water filled the cylinder. I did it to a Toyota once. Water doesn't compress and if there's enough water to prevent the piston from reaching top dead center, something's got to give. I would expect the piston to crack around the wrist pin. I can't imagine any special procedure. My Toyota broke a piston and bent the crap out of the connecting rod.
 

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As others have stated, it seems like you did everything correct as per your post. It sounds like something was already wrong with the piston before you pulled the plugs. With the plugs pulled, the water has a place to go, and therefore should not hydroloc. I've also never seen the piston break off a chunk due to hydrolocking. I have only seen them bend or break the connecting rod and score the cylinder a little.
 
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