Allen bolts backing out under motor plate

[pura vida]

UPDATE 1/7/12 this turned out to have nothing to do with the crank as the following assumes. it was a motor strap bolt issue. the details are in the thread. i would recommend checking motor strap bolts at least once very 1000 miles.


so on my 2011 pro i am 95% sure my crank is about to fail. there is a nasty noise that is rpm dependent that is coming from under the cowling. it could only be two things and my clutch is not rubbing on anything. the strange thing is it doesn't do it all the time. warm up, trail riding, and even some full throttle pulls it runs and sounds fine. but when i really load the motor for an extended period of time it starts making a nasty knocking noise. first time i heard it was a couple rides back and thought it was my clutch rubbing on the tub/side panel or ice build up on my drivers but zero evidence of either of those. it has gotten worse and after today i'm almost positive it is the crank. the other three people with me agreed. the frustrating part was the inconsistency. i have a great dealer but how the heck am i going to convince them my crank is going out if it won't do it at idle unless it has just been under a sustained load? the other option is to keep riding it tell it blows but that is pretty much screwing my buddy b/c he will have to tow it out. i actually tried to get it to blow today although that would have been expensive b/c towing was not an option and helicopters are expensive.

pv

 

[Aussie Niko]

can only think of putting it on a dyno to simulate the same motor effects..

 

[icr]

A dial indicator might show something. Otherwise tow your buddy's sled around big lake until your crank let's go then he can tow you back.

 

[pura vida]

hmmmm, that's not a bad idea actually. that's about the only way to get a similar load that can be found in the mountains.

 

[glassman]

Check your engine mounts. Doubt is the crank as that would not be intermittent. A dial indicator will tell you if the crank is out of tune.

Sent from my SGH-T959D using Tapatalk

 

[Hawkster]

Are you sure that it's not the primary clutch about ready to break off near the end of the crank ?

 

[Demo250]

I wouldn't be so quick to run your sled into the ground trying to get it to blow. I have my doubts it's the crank. If it is as bad as you say it is and it actually was the crank, I see no way that the motor could be holding itself together under heavy load.

Like Hawkster said, the primary may be ready to grenade itself in half. I've seen the postings on here of the clutch literally braking in two and yet still being ridable. One guy didn't even know it broke until he stopped and looked in. Supposedly a bad batch of clutches out there, you may be one of them?

Edit: Even that seems weird to be making noise though. You think it would just break with no warning. Hmmm, I'll be watching this thread. Let us know what happens or if you figure anything out.

 

[icr]

My clutch didn't make any noise before it broke.

 

[pura vida]

mounter mounts are brand new and the "updated" 2012's. primary is also brand new this season. balanced, indexed, and faced by carl's. couple hundred miles at the absolute most. plus after is start doing it, it will do it at idle. yeah it is the intermittent-ness that gets me...

 

[xmk1080]

Pull the clutch off and take the dust cover off that covers the pto seal. The seal goes out and takes the bearing out or the bearing is bad and it will take the seal out, there will be a bunch of oil around the seal if it is bad. Suposively polaris switched bearings some where in the "11 production and it has the same part number, it is suposted to be a thicker race now. Mine did something similar, it made a graveling sound at idel. Some times worse than others, inconsistant. It lasted another 300 miles until the bearing came apart. Before mine went down and when it was making that noise, I pulled the dust cover off and there was a ton of oil around the seal. Now I have a completely new long block. Now I have a Indy Dan balanced clutch and cut sheaves, new updated "12 motor mounts, new motor, turned the oil pump up, geared down to 19/43, tied secondary, and balanced the weights! Some of the weights were half a gram off or more. Also the turn around time was amazing on my clutch, Thanks Indy Dan. He cleaned it, checked for a bent shaft, set belt to sheave clearance, cut the sheave angle and balanced it. Hopefully the problem is gone, lol. Hope this helps, Justin.

 

[pura vida]

first, hopefully it was obvious i meant MOTOR mounts not mounter mounts in my previous post.

justin, thanks, good to know, i'll check out the seal. i've pretty much done everything else listed. yeah, polaris's "matched" weights usually aren't that matched. not at least with the ones i have found. plus they can be significantly off from where they are suppose to be. i always grind my weights so they match to within a tenth of a gram only b/c my gram scale isn't any more precise.

although i was thinking mine sounds more like a rod bearing, causing the rod to rattle back and forth. didn't think a dial indicator would show anything. and, at this point, it sound fine at idle and even cruising down the trail. it only shows up after a hard long pull, for now. it will be interesting to see how it changes as time goes on, assuming i don't/can't get it fixed right away.

 

[Bull]

it'd be a pity to "go ahead and try to blow the crank" only to find out it is another issue.....and yes, it eventually caused the crank to blow...

 

[m8sandman]

i'd also say rod bearing, the knock is usually caused by the slop in the bearing when the rod hits top or bottom dead center and heads the other direction. unless its really bad usually it will only do it at tdc when the sprark fires. every crank i've ever seen break either will have a ton of endplay or have a very ecentric wobble at the end. only way to tell if its the rod for sure is to tear it down and look. if its bad enough you may be able to just pull the cylinders and wobble each rod or look down inside. if not, the case would have to come apart and inspect the bearing/crank. if you can get it to knock continuously long enough you can pull a plug wire from one cylinder and run it and see if the knock goes away. then hook it up and do the other. if unhooking one of the wires makes the noise stop you know which bearing is probably going bad. have also seen pistons starting to go make the same noise. running it till it blows would be my last choice, instead of just replacing a set of pistons or rod bearings you can easily break the case and end up needing a whole new motor...

 

[Woodsrider]

You can check for slop in the rod bearing by placing a plastic straws in spark plugs hole then gently wiggle clutch back and forth. Works best with the pistons in the middle of the stroke. Straw should move up and down with very little movement of the crank. I found a bad big end bearing this way before it did any damage.

 

[pura vida]

update: found one issue

i'll have to try the straw thing. that is a good idea, thanks.

so i found one issue that is definitely causing an issue. although my motor mount are brand new it looks like the motor plate/strap on the mag side is extremely loose. i knew something was wrong after pulling the pipe/can and lifting on the y-pipe and there was clearly more movement than there should have been. then prying on the the recoil cover i could see everything lifting out of position and moving around. as dumb as it sounds now, i'm guessing it is a pretty safe bet that is where the bolt i found in my tub came from... anyone hear of a motor plate bolt just falling out??

so that is clearly an issue that has to be fixed but how is this causing my noise if there is no sign of wear or impact on the clutch or any of the surrounding plastic? it was distinct and sustained enough there there should be evidence of it. now the question is do i take it to the dealer and have it taken care of under warranty or pull the motor and do it myself? i really don't feel like taking the time to do it and if other issues are found they can all be dealt with. but if i do it my self i'll have this specific issue taken care of much faster and be able to ride this week to see if this was my entire issue or not.

 

[theultrarider]

i'll have to try the straw thing. that is a good idea, thanks.

so i found one issue that is definitely causing an issue. although my motor mount are brand new it looks like the motor plate/strap on the mag side is extremely loose. i knew something was wrong after pulling the pipe/can and lifting on the y-pipe and there was clearly more movement than there should have been. then prying on the the recoil cover i could see everything lifting out of position and moving around. as dumb as it sounds now, i'm guessing it is a pretty safe bet that is where the bolt i found in my tub came from... anyone hear of a motor plate bolt just falling out??

so that is clearly an issue that has to be fixed but how is this causing my noise if there is no sign of wear or impact on the clutch or any of the surrounding plastic? it was distinct and sustained enough there there should be evidence of it. now the question is do i take it to the dealer and have it taken care of under warranty or pull the motor and do it myself? i really don't feel like taking the time to do it and if other issues are found they can all be dealt with. but if i do it my self i'll have this specific issue taken care of much faster and be able to ride this week to see if this was my entire issue or not.

I was riding with another pro down here at lost a couple weeks ago. We swore he had a rod knock or a clutch going bad. Bets were a rod. Didnt sound right for a clutch. More like a lower rod bearing. Long story short, 1 of the bolts from the straps to the block had fallen out. The other 3 were finger tight at best. The holes in all 4 points in the straps have been elongated and the straps are junk at this point. Worth checking out! Sure beats a motor rebuild. Frustrating though that the factory couldnt either locktite those those and/or torgue them correctly.

 

[pura vida]

wow, that sounds exactly what i am dealing with. just didn't sound ride to be the clutch. what the heck is making the knocking noise then? thanks

pv

 

[theultrarider]

wow, that sounds exactly what i am dealing with. just didn't sound ride to be the clutch. what the heck is making the knocking noise then? thanks

pv

The motor would be knock against the straps. Have you seen an increase in belt wear in say the past 100 or 200 miles? We couldnt figure it out til it got bad enough that when we would pry on the motor it would move around more that we thought it should. Then when Chris got home he found a bolt in the bottom of the belly pan. Then the search for where it came from began. You know the rest of the story... Hope that is all yours is. Better yet if you can get it warrentied!

 

[Bull]

i'll have to try the straw thing. that is a good idea, thanks.

so i found one issue that is definitely causing an issue. although my motor mount are brand new it looks like the motor plate/strap on the mag side is extremely loose. i knew something was wrong after pulling the pipe/can and lifting on the y-pipe and there was clearly more movement than there should have been. then prying on the the recoil cover i could see everything lifting out of position and moving around. as dumb as it sounds now, i'm guessing it is a pretty safe bet that is where the bolt i found in my tub came from... anyone hear of a motor plate bolt just falling out??

so that is clearly an issue that has to be fixed but how is this causing my noise if there is no sign of wear or impact on the clutch or any of the surrounding plastic? it was distinct and sustained enough there there should be evidence of it. now the question is do i take it to the dealer and have it taken care of under warranty or pull the motor and do it myself? i really don't feel like taking the time to do it and if other issues are found they can all be dealt with. but if i do it my self i'll have this specific issue taken care of much faster and be able to ride this week to see if this was my entire issue or not.

warranty...without a doubt. need that on record in case other issues pop up.

 

[Woodsrider]

If a bolt came out then the other(s) is/are loose and I bet the strap(s) are junk.