Do these pictures tell you why this motor seized?

mx100 · Apr 23, 2013

I think I was riding my XP on borrowed time. I was ripping up the trail to the Deep snow, and I came to a quick stop. Sled has 3700 hard mountain miles on stock bottom end, and 1300 miles on the dual ring SPI pistons. Lost the PTO piston.

PTO plug, newer than the mag plug.

MAG plug

Head, left is PTO

This is the top of the cylinders before pulling them off the case.

Top of piston stuck in the top of the cylinder

Just pulled the cylinders off the cases, and this is what I found!

The Pto rod bearing is locked up solid, and also took out the cases. I just did the oil delete, and made it maybe 4 miles. I added enough oil in the fuel tank for 10.6 gals at 32:1, then topped off the tank. I am not sure, but I think it was just time for a rebuild. Did I miss something? If you have a different opinion, please give your 2 cents.

I am looking for cases, (prefer used for the price). I think I will need a new monoblock, the gouges look deep. I am planning on a new, trued crank, and haven't decided what I am doing with the top end yet. I would love to do a big block, but the PURE pressure to do a Turbo is OVERWHELMING!!! Does anybody have any advice on where to get parts? New and Used. Thanks.

avycital · Apr 23, 2013

Call BJ at sled head racing 6127183861

Tell him what you need he has it all

LoudHandle · Apr 23, 2013

Where is the rest of the porcelain from the PTO spark plug? Was that the cause or the effect?

Modoutlawkart · Apr 23, 2013

Rings were wore snaged exhaust port bad things happened

rndy67 · Apr 23, 2013

X2 big John will have used cases and all the parts you need. His work and customer service is the best around.

mx100 · Apr 23, 2013

LoudHandle said:
Where is the rest of the porcelain from the PTO spark plug? Was that the cause or the effect?

The little piece of porcelain was laying on top of the piston when I took the head off. I am guessing it was the effect.

tukernater · Apr 24, 2013

I beleave Dave has a great deal on trued cranks and cases his price was so close to used cases I would go new.

frog · Apr 24, 2013

You added oil to the fuel in the tank but what about the fuel in the fuel lines, fuel pump and carbs?

Mach-ster · Apr 24, 2013

Give Dave a call he's got plenty of new cases and anything else your going to need. As for the oil delete....I'd hook it back up with the new case as lack of oil will make em go real quick!! there is reasoning behind that and Dave can fill you in as to why.

89sandman · Apr 24, 2013

i'm with frog did you run the sled with oil in the gas before the delete? would take a little bit of time for the fuel and oil from the tank to get to the carbs? if you didn't you'd be running straight fuel with no oil.

RKT · Apr 24, 2013

If it were an oiling problem, then you would have both sides with failure or at least evidence of "stress" and the good side shows no evidence..

What I see is a piston failure that caused a crank failure.. By piston failure, I do not mean a piston melting, but a piston "failing"

joshkoltes · Apr 24, 2013

what does the other piston and cylinder look like? some minimal scoreing or still a visible cross hatch. my xp popped after i towed it down a slushy salty dirty road un covered ONE time, made it a mile and locked up

Red-eye · Apr 24, 2013

Connecting rod bearing bearing failure causing the piston to over stroke and hammer around and destroy the piston. It would detonate and take out the porcelin on the plug. Wrist pin seizure that rocked the piston with simular results. Don't see any heat on the wrist pin though. My best guess without seeing it.....Was it knocking just before it went boom?

Danzick · Apr 25, 2013

im with kelsey on this one. looks like that piston just failed. as said before. bad things happen.

mx100 · Apr 25, 2013

Carbs were drained of raw gas, the only raw fuel was in the fuel pump. There seams to be residual oil in the cases, but I need to look it over a little more. The mag side (good) piston looks good, cylinder has X hatches still, the connecting rod bearing feels good, no sign of problems.
The connecting rod bearing on the pto (bad) Is locked up solid, and the wrist pin bearing (upper) is loose, and the pin actually spins freely.

I have done the oil delete on other sleds, and had no problems, and I know a ton of people do it with success, both mountain riders and trail/racers. I have called a couple of engine builders, and asked their opinion on the delete. I got mixed answers, but one really sticks out to me. The way these cases are designed, and the way the oil is injected in the cases is critical in the engine longevity. Oil being injected almost directly to the connecting rod bearing is far superior than the oil in the gas that works it's way down there.

I think a tired bearing, along with less oil than normal could have caused this problem. I still haven't discarded the idea of the piston failing 1st.

I was riding with a guy that deleted his oil pump the same time I did, and he has about the same millage on his sled as I do. He added oil to the gas tank just like I did. The only difference is, he is still riding.

Red-eye · Apr 25, 2013

The mixture of fuel and oil gets pulled down into the crank as soon as the engine turns over. I'm sure there was enough oil left from the injection system, in the case, on start up also.
If the piston failed from a cracked skirt etc, It usually just jams pieces in the connecting rod area and makes it hard to turn from debris. Is the bearing acually seized, with signs of heat or full of piston junk?

mx100 · Apr 25, 2013

The rod bearing is seized! I yanked on it hard, really hard and there is no movement in it at all! I also looked the top of the case's over real good for oil and the pto (bad) side is really, really dry compared to the mag side. I don't know if that is because of all of the carnage that took place on that side, or if something else happen. The rod is locked low on the crank in the cases, and I can't tell if it has been over heated or not. I need to split the cases.

Red-eye · Apr 25, 2013

The one head is very clean for a piston that just failed. Is it possible there was a coolant leak? That might explain the lack of oil on that side and a connecting rod failure. The injection lines that are joined on the case are full of antifreeze, or is that from taking it apart? Don't know if I agree on joining them, they should be individually caped to keep the cylinders seperated. I think others do it without problems.

Red-eye · Apr 25, 2013

Why was the PTO side plug newer? Was that cylinder running bad?

mx100 · Apr 26, 2013

Two weeks before this happened, I was checking my plugs while on the mountain, and one of the plugs accidentally got dropped under the motor. I had to put a different plug in at that time. While looking for the plug under the engine, that's when I noticed my oil cable was broke and I decided to delete the pump.
I dont think there was a coolant leak before this happened. When the rod seized and took out the bottom of cases I think that's where all of the antifreeze came from and washed the case and rod clean of oil. There was a ton of antifreeze in the pipe when I pulled it and It poured antifreeze all over the ground right when it seized up. That's when I knew I broke the case somehow. I agree about connecting the two nipples together, they should have just been plugged of.

Do these pictures tell you why this motor seized?

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