How Do You Know If A Crank Bearing Is Bad? - Snowmobile World : Your #1 Snowmobile Forum
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post #1 of 15 (permalink) Old 02-13-2006, 08:57 PM Thread Starter
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i have a vibration/humming sound i can't pinpoint. sled start first pull, compression is high and runs good. how would i know if it is a crank bearing? maybe a driveshaft bearing? any help would be great!!! i am thinking of riding the sled like this a couple times, but don't want to if it may be the crankshaft bearing...... :bash:
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post #2 of 15 (permalink) Old 02-13-2006, 09:40 PM
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Does the humming sound change pitch with engine RPM ?
Does the humming sound change pitch with sled speed ?
Does the humming sound change pitch when decellerating ?
Does the humming sound change pitch with temperature ?
Does the humming sound change pitch with snow conditions ?
These are some things you need to note when you are riding. For example:

A crank bearing on the PTO side will squeal amd allow the primary clutch to rattle. Its sound will change with increased RPM.

A jackshaft bearing will only make noise under way and increase with speed.

Temperature & snow conditions will affect ice build up in the tunnel and cause rubbing.

Try getting all the conditions dow on paper before taking things apart.

Located in Western Quebec

Kilos traveled this season 2750
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post #3 of 15 (permalink) Old 02-13-2006, 11:20 PM
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idle the sled and spray ether towards the crankshaft bearing, if the idle remains then the seal is fine and usually the bearing also. if the sled's idle becomes greater then you have at the least a seal gone.

IF WE GIVE ALL THE PROFIT TO THE IMPORTS WHAT WILL BE LEFT?
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post #4 of 15 (permalink) Old 02-14-2006, 09:15 AM
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idle the sled and spray ether towards the crankshaft bearing, if the idle remains then the seal is fine and usually the bearing also. if the sled's idle becomes greater then you have at the least a seal gone.
[/b]
Good suggestion Paul, but I'd like to suggest the use of WD-40 instead. It's safer and will tell the same story as ether.
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post #5 of 15 (permalink) Old 02-14-2006, 10:38 PM
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Good suggestion Paul, but I'd like to suggest the use of WD-40 instead. It's safer and will tell the same story as ether.
[/b]
i don't like my WD40 bottle in the winter, like something else around here it don't squirt that good.

probably from lack of use.

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post #6 of 15 (permalink) Old 02-14-2006, 10:51 PM
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post #7 of 15 (permalink) Old 02-15-2006, 06:30 AM Thread Starter
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Does the humming sound change pitch with engine RPM ?
Does the humming sound change pitch with sled speed ?
Does the humming sound change pitch when decellerating ?
Does the humming sound change pitch with temperature ?
Does the humming sound change pitch with snow conditions ?
yes to all these,
i am leaning towards a jack shaft bearing... thanks for all the tips, i will check the crank bearings/seals as sugested. if it is a jackshaft bearing, what kind of damage will riding a 100 miles or so cause? winter is almost done here and i jsut don't have the time to tear into it for 1 more ride, i was hoping to jsut ride it and fix it in the spring......
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post #8 of 15 (permalink) Old 02-15-2006, 11:16 AM
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Quote:
Does the humming sound change pitch with engine RPM ?
Does the humming sound change pitch with sled speed ?
Does the humming sound change pitch when decellerating ?
Does the humming sound change pitch with temperature ?
Does the humming sound change pitch with snow conditions ?
yes to all these,
i am leaning towards a jack shaft bearing... thanks for all the tips, i will check the crank bearings/seals as sugested. if it is a jackshaft bearing, what kind of damage will riding a 100 miles or so cause? winter is almost done here and i jsut don't have the time to tear into it for 1 more ride, i was hoping to jsut ride it and fix it in the spring......
[/b]
Hi spinner,

Does your sled smoke irregularly when idling?

Thanks
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post #9 of 15 (permalink) Old 02-16-2006, 05:18 AM Thread Starter
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yea, it seemed to be smoking more than usual. why????
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post #10 of 15 (permalink) Old 02-16-2006, 09:08 AM
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Wd-40 has changed the propellent, it is no longer flamable.

MXZer
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