Sled blown up from water in fuel???

[rvrbum4]

Ok, here's the scenario. About 400 miles ago (in December) compression was 125 on both sides. Yesterday went out for a ride after fueling up and about 10 miles in I gave it the beans and the temp light (det) flashed and it died. Could not pull engine over. Removed plugs and engine turned fine. Put new plugs back in and barely starts, wont idle at all and runs like total crap at half throttle like its not really even running on one cylinder. Rev it up enough and you can get it on a trailer (barely). Got it home and left plug was black and "normal" looking. Right plug was clean as a whistle but slightly wet. Odd thing is the right plug and cylinder don't really smell like gas. I thought aha! water in fuel but lets do a compression check before we start working water out if system. Right cylinder is still 125 but left is only 45.
My question is this: Is this normal for an engine failure? Could water in the fuel cause this engine failure? I did not check for water after the bad news, just shut the hood and logged on to jd.

 

[whitedust]

Difficult question tear it down see what you find?

 

[ezra]

could deff be water .
drain the coolant below bottom of jug and unbolt head. take a pic and post .
can prob tell what kind of burn down u had then.
if not water then u have to fig out why before just slapping a new piston in.
and what sled ?

 

[rvrbum4]

Sorry, knew I'd forget something trying to keep post short!
It's a 05 RMK 700.
I'll pull the head and get pics shortly. I don't know that I know enough to rebuild so I didn't want to mess up someone elses diagnostics by tearing it apart.

 

[timo]

of all the burnt down sleds i've been part of it's rarely ever water in the gas as being the culprit.
every time we think it is, but never turns out to be the case.
could be a myriad of problems. like ez said most important thing is finding the cause before putting time and money back into it.

 

[rvrbum4]

If I did this right the pictures are attached.

 

[rvrbum4]

Hey it worked! Cylinder wall definitely scored/scratched around/above the power valve. Also is it normal to have the two little worn angles on the exhaust side of the piston? The pic of the head shows the dark carboned side is the bad side and the clean side is the good compression side which was rebuilt due to a power valve failure last year. If I look close it looks like water beads inside the clean side.
I also noticed that their air bubbles in the oil line that goes to the crank seal pto side. My son did say he thought it didnt use as much oil as he thought it should but not all the time.

 

[G]

No, it is not normal to have worn areas on the exhaust side of the piston. For some reason your piston got hot and began melting. The pieces of piston got into the ring lands and you'stuck a ring'. That is what caused the engine to lock up. Very often when things cool down the ring will break loose and the engine will start again just as you described. But the damage is done. It is not a four corner burn which would indicate a cold motor. It is not a hole through the top of the piston which would indicate total fuel starvation. It looks like partial fuel starvation. I don't believe it is an oil problem. Best guess would be some kind of obstruction in the fuel delivery system. Or water in the gas. Water could do that. When you take a head off a water cooled sled it is very easy to get coolant water into your cylinders so I wouldn't be too concerned about the water droplets you found. If I were you I would stop right where you are and take it to a Pol shop. Let them check the carbs for water or whatever else went wrong. I am not that familiar with Pol's power valve system but I doubt if an inoperative powervalve would cause this.

 

[ezra]

. no the flat spots are not normal . could be gas? plugged jets? I cut and pasted this for u.Normally the piston temperature is higher on the exhaust side so catastrophic problems will appear there first. There are several reasons for a failure like this, here are the most common; air-leak at the magneto side crankshaft seal, too lean carb jetting, too far advanced ignition timing or faulty igniter box, too hot of a spark plug range, too high of a compression ratio, too low octane fuel.


link to reading piston wash
http://www.smellofdeath.com/lloydy/piston_diag_guide.htm
could be bad fuel how deep are the groves? did u try acid washing the groves yet? could be deposits of piston and not really a grove .if it was just after gas fill it could be that . kid is sure it was not acting up before fill up? did u dump whole tank in to a bucket to see if water came to top of gas
guess at this point u are pulling jug to look at piston skirts . pretty ez to replace pistons .if u can pull a head u can replace pistons.

 

[lee]

water to the bottom of fuel container

 

[ezra]

water to the bottom of fuel container

that is correct my bad

 

[rvrbum4]

Pulled the piston and cylinder. Piston has definitely got scoring/scraping all the way around especially on exhaust side and the rings on the exhaust side are totally stuck and buried in piston material. I am attempting a home acid wash of the cylinder to see if I can salvage it. Another thing I didnt expect was that I had to beat the wristpin out of the piston, carefully of course.
How does one do a proper acid wash of a cylinder, in case my way doesnt work.
As always THANK YOU ALL for your honest input and information!!

 

[ezra]

I always get some gloves and just pour muriatic in the jug on the alloy and scrub with a old toothbrush if needed.rinse and repeat as needed.
for wrist pins I take a deep well socket just smaller than pin then a larger socket on other side to accept wrist pin.
push together with a quick grip trigger style clamp.

 

[ezra]

lets see piston

 

[indy_500]

I wasted about 4 hrs of my time cleaning up a cylinder with muriatic acid that wasn't salvagable. You can exchange them with millennium technologies for $215 if that's the case. Being a carbed sled if only one side went down chances are you have a plugged jet or an air leak.

 

[rvrbum4]

First pic is intake side, second is exhaust.

 

[rvrbum4]

Yah I hope its not pto crank seal because I already have it torn apart and wont know until its back together.
I'm feeling pretty helpless here and I may be in a little over my head here but with some help I'll get through it. Just trying not to pay a shop and learn something along the way.
Ezra- I put faith in your opinions.

 

[ezra]

well the sides tell me your prob not going to salvage that jug . it was deff running real lean . no fast idol before or slow to rev down ? typically u have a few signs of crank seal before even if it is hind site .
chit in jet is deff viable option .
have u blown a belt recently?

- - - Updated - - -

fyi splitting the case is more intimidating than the job really is in a 2st
1 more thing if u don't want to go that far. slap some cheep spi pistons and gaskets . clean carbs drop in new gas. then run it spraying starting fluid around seal. that would not have really worked the way it was running before . but would if fresh. kind of a pain but better than burning down again.
1 other thing if it is crank seal on a Polaris 700 800 it usually goes deeper than the seal. crank run out and warped cases are the norm if getting multiple crank seal issues on a poo. indy dan made a carrier from that

 

[rvrbum4]

Yah jug is pretty rough. Never had high idle or slow to idle down but have had some low idle issues. And when starting when warm would have to give it some throttle to get it started which wasnt an issue last year.
It has died a few times out of the blue but thought it was a kill switch because disconnected it and no issues for a few times of riding.
Have not blown a belt in two years weve owned it.

 

[ezra]

high idol and peaky slow to idol down is the norm. could be that piston has been on the way out for some time. I always do both at the same time. what are u saving buy doing 1 90 bucks?