engine makes clanking/crunching noise when pulling starter

snowy-colo-tim · Jan 9, 2017

I've got a 2008 RMK 600, its been a great sled even with short track, and I was blasting though all the new snow running great all day, then engine starts losing power then kinda makes a grinding noise, motor goes from normal pitch to a low poof poof sound. pull starter cord seemed stuck, removed the belt, moved the clutch by hand and it seemed to free the pull starter. Tried to start and when it did start it barely ran super rough. Pulled the plugs and i see the 2 pistons moving, but the motor makes a clanking/crunching noise when pull starter drawn slowly without plugs - its tougher than normal to pull the cord. I just realized I had not adjusted drive chain tension for years although i change the oil annually. Maybe i should drain and look for debris in the chaincase oil?
Perhaps its a crankshaft bearing or drive chain gear issue. I'd love to bring it back to life.
Any ideas where to start or diagnose ?

Not sure if its related but the machine was upside down stuck in a bush on a cliff for about 8 hours until i got about 5 guys to help fish it out. It started right up, coolant and oil appeared normal and it did not overheat all day.

mtncat1 · Jan 9, 2017

the engine probably sized pull the head and inspect then go from there. i hope it's not much more than a top end

snowy-colo-tim · Jan 9, 2017

if the engine seized would the pistons be locked in the cylinder?
they move freely. if the rings and bore seal were compromised then compression test would tell.
maybe a bubble in the 2 stroke oil line (from being upside down for hours) blocked the flow.

since i heard a grinding right before the motor stalled, and a change in the exhaust sound, i was leaning toward timing related.
does the chaincase chain and gears affect timing on the liberty 600 HO ? is there a timing belt?

Betterview · Jan 9, 2017

snowy-colo-tim said:
if the engine seized would the pistons be locked in the cylinder?
they move freely. if the rings and bore seal were compromised then compression test would tell.
maybe a bubble in the 2 stroke oil line (from being upside down for hours) blocked the flow.

since i heard a grinding right before the motor stalled, and a change in the exhaust sound, i was leaning toward timing related.
does the chaincase chain and gears affect timing on the liberty 600 HO ? is there a timing belt?

The two stroke motor has a stator on the mag end of the crank. Ignition coil and trigger coil are there. Definitely an engine issue. From what you describe it could be a crank bearing, but I would agree that the upside down period probably left an air bubble in the oil line leading to some piston seizing and possibly a dropped skirt.

snowy-colo-tim · Jan 9, 2017

done some research, when the guys wiggle the connecting rod and point out the failed rod bearing in this youtube,
it kinda sounds like the clanking i get when i pull the starter cord.
back when the motor stopped some bits might have bound up caused the crank/pull starter to be stuck and when i removed the belt and moved the clutches it might have dislodged and freed it up.
https://www.youtube.com/watch?v=1wOyjRZWW1U
a failed rod bearing could change the exhaust sound, that i remember hearing.
if i pull the top off a bit i could diagnose those rod bearings.
this make sense?
is there oil in the crankcase or is it just grease on the bearings?

Betterview · Jan 9, 2017

snowy-colo-tim said:
done some research, when the guys wiggle the connecting rod and point out the failed rod bearing in this youtube,
it kinda sounds like the clanking i get when i pull the starter cord.
back when the motor stopped some bits might have bound up caused the crank/pull starter to be stuck and when i removed the belt and moved the clutches it might have dislodged and freed it up.
https://www.youtube.com/watch?v=1wOyjRZWW1U
a failed rod bearing could change the exhaust sound, that i remember hearing.
if i pull the top off a bit i could diagnose those rod bearings.
this make sense?
is there oil in the crankcase or is it just grease on the bearings?

The crankcase is oiled by oil injection. All the fuel and oil travel through the crankcase prior to traveling up through the transfer ports to the top of the piston.

Betterview · Jan 9, 2017

You could pull off the Y pipe and look at the pistons to see if the skirts are fine. Also pull the heads to see if there is damage on the top of the pistons. If the pistons are scored you can probably get by with refreshing the top end. If there is damage on the top of the pistons you will need to tear down further to see if it was done by piston skirt (better) or a bearing or rod failure (not good).

volcano buster · Jan 10, 2017

I had a funny sound/feel last winter on my '10 600. Took the intake off as I was cleaning injectors and things didn't look good. I had broken a ring somewhere along the way and at 2000 miles it was time for a top end rebuild.

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engine makes clanking/crunching noise when pulling starter

snowy-colo-tim

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snowy-colo-tim

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Betterview

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Betterview

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