Sheared crank pulley off! + vibration at speed....
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Sheared crank pulley off! + vibration at speed....

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    Off Road Badass Bonzen's Avatar
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    Default Sheared crank pulley off! + vibration at speed....

    Was about 8 miles up river from Fishers Landing last friday everything running great and all the sudden I could feel a vibration/cavitation feeling...reminded me of what it feels liek when you suck up weeds in the pump. Boat felt like it lost about 20% power also. So we beach it on a sandbar and I pull the inspection cover and no weeds... none in the grate. So nothing else to do but pull it out of the water. So we go to leave to head back down river and now the boat wont start. Great. So im cranking it over again and again, pumpin the foot pedal and finally we get her going but it's missing, cutting out like there is a fuel blockage or air in the lines...Finally after feathering the throttle for about a half mile it clears out and runs decent all the way back to the ramp but still got this bad vibration while on the gas. Pull her out of the water, take out the bench seat to check the motor out and boom...no crank pulley. Pulley is laying under the oil pan and the harmonic balancer still has the three allen bolts with piece of crank pulley stuck to them. So I unscrewed the allens (which werent very tight at all) and removed the excess metal, and bolted them back in. tightened all the fuel line hose clamps, cleaned the water/fuel seperator with rubbing alcohal and she fired right up and idled smooth. Put her back in the water, hit the gas and...vibration still there. What the hell...so now you can kinda hear what sounds like a bad bearing sound when you get on the gas....but it goes away at idle. I checked the impeller, it doesn't have any big gouges, just the standard pitting on the faces of the blades and rough edges, (aluminum impeller) So im thinking it's the main greasable pump bearing that the shaft runs through. Thats my best guess right now, any ideas here? Motor is a bone stock Marine Power 454, TBI, Berkley pump. Whats weird is how all these issues started to happen at the same time...could the crank pulley shearing off cause something else to go bad?

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    the pulley shearing off is probably a result of the vibration. they're not designed to have any type of load of force on them other than a belt for some minor things. usually when stuff breaks it breaks the weakest part first.

    do yourself a favor and disconnect the driveline and run it on a hose and look for vibrations without the crank pulley on, just the motor and make sure the important part is in working order. id check the plugs and make sure they look good, no misfires or damaged electrodes from perhaps a bent valve or something. then put the crank pulley back on, make sure the bolts are tight (i put a TINY amount of loctite or locking washers are a must for anything that spins), make sure pump spins freely by hand, then hook up the driveline again and go for a spin.

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    Default Bear with me here...

    OK, the pulley that bolts onto the harmonic balancer was laying in the bottom of the boat, but the bolts that hold it on were still screwed into the balancer.... Did the pulley actually break at the bolt holes? AND, how did you bolt it back on if the bolt holes were broken away?.... AND, the motor shakes....... Pull number one plug, bump motor over until that piston is all the way to the top, and see where your timing mark is on the balancer... it should be at zero, or real close.... If it's not, the balancer outer ring has spun, which could be what knocked the pulley off.... The actual counterweight is part of the outer ring, that could be the reason for the shake.... I've seen it happen before, and based on a couple of those occasions, you've been lucky so far... It is also possible IF that ring has spun, to throw the engine far enough out of balance to hurt something inside....
    Ray
    Last edited by Moneypit; 08-27-2012 at 01:18 PM.
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    Senior Member watergun4u's Avatar
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    Quote Originally Posted by Moneypit View Post
    OK, the pulley that bolts onto the harmonic balancer was laying in the bottom of the boat, but the bolts that hold it on were still screwed into the balancer.... Did the pulley actually break at the bolt holes? AND, how did you bolt it back on if the bolt holes were broken away?.... AND, the motor shakes....... Pull number one plug, bump motor over until that piston is all the way to the top, and see where your timing mark is on the balancer... it should be at zero, or real close.... If it's not, the balancer outer ring has spun, which could be what knocked the pulley off.... The actual counterweight is part of the outer ring, that could be the reason for the shake.... I've seen it happen before, and based on a couple of those occasions, you've been lucky so far... It is also possible IF that ring has spun, to throw the engine far enough out of balance to hurt something inside....
    Ray
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    Senior Member Brendellajet's Avatar
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    What kind of balancer? I had one of those professional products deals start coming apart on me. Noticed the balancer wobbling...the outer ring came off the hub. Was under warranty but they wouldn't send me a new one(not that I wanted it...)
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    Off Road Badass Bonzen's Avatar
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    I never bolted the crank pulley back onto the balancer, it actually ripped off the bolts and left parts of the pulley still attached to the bolts. I just removed the bolts, pulled off the pieces of crank pulley, and re-threaded the bolts back into the balancer. I put it back in the water to test it out again but the issue was still there when you get on the gas.

    The balancer and crank are stock I assume, I really dont know. Dont look like anything special. The Boat is a 1994, maybe it was just time for it to break, maybe the bolts were slightly loose enough to cause the crank pulley to wiggle loose and shear off. if the balancer is bad, how would i tell? it looks like it's running true visually. And like I said the motor idles fine ansd smooth, like it always does. It's only when you get on the gas that it has a vibration/shudder feeling. It's still gets on plane and runs about where it should speed wise. I would have to assume if it was engine internals then it would detonate itself immediately. I probably ran it for about 6-8 miles after the issue began, had to get back to the dock.

    Kinda hard for me to believe that the pulley would shear off and then another unrelated issue would simultainiously occur, causing it to continue to vibrate at speed even without the messed up crank pulley on it.....I'll pull the spark plugs, check for damage, and after that pull the driveline and see if the noise is isolated to the motor or the jet drive.

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    Default Read replies???

    Quote Originally Posted by Bonzen View Post
    I never bolted the crank pulley back onto the balancer, it actually ripped off the bolts and left parts of the pulley still attached to the bolts. I just removed the bolts, pulled off the pieces of crank pulley, and re-threaded the bolts back into the balancer. I put it back in the water to test it out again but the issue was still there when you get on the gas.

    The balancer and crank are stock I assume, I really dont know. Dont look like anything special. The Boat is a 1994, maybe it was just time for it to break, maybe the bolts were slightly loose enough to cause the crank pulley to wiggle loose and shear off. if the balancer is bad, how would i tell? it looks like it's running true visually. And like I said the motor idles fine ansd smooth, like it always does. It's only when you get on the gas that it has a vibration/shudder feeling. It's still gets on plane and runs about where it should speed wise. I would have to assume if it was engine internals then it would detonate itself immediately. I probably ran it for about 6-8 miles after the issue began, had to get back to the dock.

    Kinda hard for me to believe that the pulley would shear off and then another unrelated issue would simultainiously occur, causing it to continue to vibrate at speed even without the messed up crank pulley on it.....I'll pull the spark plugs, check for damage, and after that pull the driveline and see if the noise is isolated to the motor or the jet drive.
    Try reading the replies... It's very easy to tell if the outer ring has moved....
    Ray
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    Senior Member Oldsquirt's Avatar
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    Quote Originally Posted by Moneypit View Post
    The actual counterweight is part of the outer ring, that could be the reason for the shake.... Ray
    Are you absolutely sure about that? All the stock-type balancers I have seen for externally balanced engines, as well as the ATI for my BBC, have the counterweight on the hub not the outer ring. Having the outer ring NOT be neutral balanced would be a real issue. Damn thing would be trying to throw itself off all the time.
    Last edited by Oldsquirt; 08-27-2012 at 08:43 PM.

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    Quote Originally Posted by Oldsquirt View Post
    Are you absolutely sure about that? All the stock-type balancers I have seen for externally balanced engines, as well as the ATI for my BBC, have the counterweight on the hub not the outer ring. Having the outer ring NOT be neutral balanced would be a real issue. Damn thing would be trying to throw itself off all the time.
    You have to forgive him Oldsquirt.
    You are right. If the outer ring was where the imbalance was placed, the damper would self destruct in mintues, if not sooner. No counterweighted damper has the imabalance on the outer ring. Not ONE!


    My guess is that what ever is causing the vibration is what took out your pulley. Seen more than one crank broke in 2 that you could still run because the crank broke on an angle. Usually across a rod pin arm. Usually number #1 arm.



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    Last edited by gn7; 08-27-2012 at 09:11 PM.

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    Quote Originally Posted by gn7 View Post
    You have to forgive him Oldsquirt.
    You are right.

    My guess is that what ever is causing the vibration is what took out your pulley. Seen more than one crank broke in 2 that you could still run because the crank broke on an angle. Usually across a rod pin arm. Usually number #1 arm.
    of course he's right. he's a perfessional .

    i did that once. corvair. thing kept on running. shut off and started several times. was just running a bit rougher than normal . kinda startling to find a busted crank. and it did all that in the shop without going anywhere...

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    Off Road Badass Bonzen's Avatar
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    So a busted crank is not out of the realm of possibility...great.

    Something else I remembered...I changed the oil before this trip, I was running about a half quart high...the oil pressure gauge was pegged out for the few miles before it got the vibration. It usually starts off at 80psi and drops down to around 40, but it was all the way at 80 the whole time...could it of over pressurized and somehow added too much resistance to the crank?? it has the dual oil filter setup, and i added about 5.5 quarts of oil to it after draining out all of the old oil that I could.

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    Quote Originally Posted by Bonzen View Post
    So a busted crank is not out of the realm of possibility...great.

    Something else I remembered...I changed the oil before this trip, I was running about a half quart high...the oil pressure gauge was pegged out for the few miles before it got the vibration. It usually starts off at 80psi and drops down to around 40, but it was all the way at 80 the whole time...could it of over pressurized and somehow added too much resistance to the crank?? it has the dual oil filter setup, and i added about 5.5 quarts of oil to it after draining out all of the old oil that I could.
    Nope! Not saying its a crank. But something is but if its a good noticable vibration, its probably crank related, and the vibration is what tore off your pulley. Its not odd that it all happened together. One thing let to the other. Stock crank, more than likely cast. Its not going to break part way thru.
    You could check the crank by turning it back and forth from the front with a socket on the damper bolt, and see if the back of the crank moves EXACTLY with the front. ANY movement in the front without the SAME movement in the rear is a BROKEN crank.



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    Quote Originally Posted by gn7 View Post
    You have to forgive him Oldsquirt.
    You are right. If the outer ring was where the imbalance was placed, the damper would self destruct in mintues, if not sooner. No counterweighted damper has the imabalance on the outer ring. Not ONE!


    My guess is that what ever is causing the vibration is what took out your pulley. Seen more than one crank broke in 2 that you could still run because the crank broke on an angle. Usually across a rod pin arm. Usually number #1 arm.


    I could be wrong (and I usually am ) But doesn't the small block 400 have the OUTTER ring shaved for the external ballance??

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    Default Changed it....

    Quote Originally Posted by carreradude View Post
    I could be wrong (and I usually am ) But doesn't the small block 400 have the OUTTER ring shaved for the external ballance??

    Yeah, that's what I was visualizing, I can even visualize the color of the one hanging on my wall.... I had it right the first time and changed it.. The outer ring is often used for minute adjustments with small drill point holes but the main counterweight for the 454 is part of the inner casting, as shown.... In reality, a dead hole or two can cause a shake....
    Ray

    PS In retrospect, maybe the pulley was the "effect" and there is another "cause" lurking in there somewhere.....It could be in the pump, or the short drive line.... The "shake" seems to still be there, and I don't think the pulley, by it's self, is heavy enough to make it shake as it came off, (and it's still off and it still shakes)... Look everything over, from the flywheel back, or, as suggested, if it's easy to disconnect the pump, try that.... The "outer ring" could create a shake if it's rotated and HAS drill point balance points on it... Remember, any "out of balance" will get worse as the RPMs increase... Have you verified where the timing marks are at TDC??? The crank IS keyed to the balancer, and although I've never seen a sheered key from a "flywheel end" driven set up, anything is possible... OP, please let us know what you find....
    Ray
    Last edited by Moneypit; 08-28-2012 at 10:53 AM.
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