broken rod cause opinions

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snowdad4

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southeast washington state
98 srx, mag side, rod broke. aware of no indications, sled ran fine. quick cut up a hillside, sled got stuck. dug it out, fired it, sounded like a fouled plug.

after further inspection, small hole in crankcase and you can see the rod is broken. any clues?
 
Sucked in some snow? Got a sled in our group that is down a cylinder, sounds about the same thing. Have not tore into it yet but will soon. It was "running fine" before but it happens. will see.
 
no way i can think of to suck snow. carb boots tight, airbox good and in tact, recent exhaust donuts. did douse the pipes through the lower hood vent a time or two to get some steam, but been there many times with that. piston may show different once apart tomorrow. thanks for the thought!
 
from conversations with my contacts, broken rods seem to be an oddity. snapped clean, halfway down. piston wash good. broken rod took its toll on the piston and cylinder for the brief moments it was ran.
 
plenty of oil and no piston seize. had the rod flopping not slapped the piston, most likely it would have survived. cylinder skirt shows a crack along with marks from the broke end of the rod. crosshatch still visible in cylinder as well as the rings being in tact on the piston, you would think you were looking at a new cylinder and piston.

crank rolls freely, no bearing rumble. journals in that hole dont even have a mark from the rod. rod is bent tight to the inboard journal. hard to tell if that was after or before. pin bearing at the piston is a little sticky, but not enough in my opinion for rod failure. again, perhaps carnage aftermath.

no excess fluids in the cases, never so much as an indication via the rope as to any sort of hydrolock, and i know what that can feel like. short of the rod being gone and the case hole, the bottom feels like one you would put back together without a second thought.
 
snowdad4 said:
98 srx, mag side, rod broke. aware of no indications, sled ran fine. quick cut up a hillside, sled got stuck. dug it out, fired it, sounded like a fouled plug.

after further inspection, small hole in crankcase and you can see the rod is broken. any clues?
Click to expand...


did he stuck straight ? or side way or in a strange position..maybe the case get filled with gaz and make a hydrolic lock and bend the rod
 
most likely metal fatigue and it just broke, saw an xlt with a brand new rebuilt crank do it right in front of my eyes once.
 
no hydros, as mentioned. never has.

sled was new to me off the showroom back in 98, but i did swap engines a few years back. this is where it gets interesting once the bs is cyphered.

swapped that engine out about 3000 miles ago. it originally was purchased for a drag sled project. we ran that engine hard on the grass without ever opening it up. just a stock engine in a not so stock chassis. ran good, won races, tuned well, did good.

at this point, i think something was amiss from the get go. there are a few things not adding up, not going there now. i am guessing that the rod was fatigued at one point due to a top end failure. speculation. finally, a few thousand miles later it gave up the ghost. simple as that. slight twist unnoticed hooked up and took some stuff out bad.

just putting the final touches on getting the original back in there, but it has some negative history as well. chalking this one up to bad decisions on my part.

thanks to all for the input. seems that rod only failures are a rarity. glad i got to experience one.
 
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