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  1. #1
    New Member
    Join Date
    Jul 2006
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    7
    Location
    Texas
    Tractor
    Yanmar 2210

    Default Broken Crank

    I have broken a crankshaft twice in less than 7 months in my Yanmar 2010. The first break was in August 2006 on the original, I suppose, crank. It is back in the shop after breaking the new one I just replaced from Hoye Tractor parts in August. It has had very little run time since I replaced it in August.

    Hoye said they will not refund unless the manufacture finds a defect when I return the crank to them. I really do not expect a refund. If they do not make good on the crank, I will sell the Yanmar and buy another brand. I can not afford to keep replacing crankshafts this way.

    There is no sign of seizing, no burn marks, no visible damage other than the broken crank. Looking inside at the break, all I see is that the metal seems to be very grainy. Not a solid mass as I would expect.

    My question: Has anyone else had any trouble like this?

  2. #2
    Veteran Member
    Join Date
    Apr 2002
    Posts
    2,086
    Location
    SW Ohio
    Tractor
    yanmar

    Default Re: Broken Crank

    How soon after purchase did the original crank break? Any other symptoms at that time?

  3. #3
    Elite Member DieselPower's Avatar
    Join Date
    Sep 2006
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    2,761
    Location
    Fairfield, PA
    Tractor
    JD 3020, JD 4230, JD 7410, JD 2440, MF 750, NH LS170

    Default Re: Broken Crank

    Can't say I have ever had that problem. Have you had the block checked for straightnes between the crank main journals? Do the bearing's show any abnormal wear? Where the crank broke are there any visable signs of air pockets or casting flaws?

  4. #4
    Elite Member
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    Mar 2002
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    3,310

    Default Re: Broken Crank

    Never heard of it in 5-6 years of following 4 Yanmar forums. Did the new one break in the same place as the original?

  5. #5
    Super Member RobS's Avatar
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    Jun 2000
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    6,233
    Location
    SW Michigan
    Tractor
    John Deere 790

    Default Re: Broken Crank

    How many hours on the original? Assuming lots of hours, and a fairly quick second break, I'd suspect something in the block. As Norm asked, was the break in the same place? Any chance the block froze recently? Any coolant leaks? How's the flywheel/bellhousing? Anything out of the ordinary to stress the crank could contribute.
    Rob
    ****************
    John Deere 790, 70 FEL, 7 BH, 513 cutter and other fun stuff

  6. #6
    Veteran Member MJPetersen's Avatar
    Join Date
    Feb 2007
    Posts
    1,255
    Location
    Warsaw, Poland
    Tractor
    YM 1510-D

    Default Re: Broken Crank

    That is NOT normal at all. There Must be some sort of problem with alignment or stresses that are out of specs. You need to find the cause of the breakage. Was there any vibration like somethng is out of balance before it broke. If you said where it broke ie after first rod journal or before rear main journal, it might give a clue on where to look. Also it would be VERY interesting and important to know if the first and second broke int he same place.

    Mike in Warsaw

  7. #7
    New Member
    Join Date
    Jul 2006
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    7
    Location
    Texas
    Tractor
    Yanmar 2210

    Default Re: Broken Crank

    I did not really watch the run time, but I am sure less than 40 hours.

    No, the bearings do not show abnormal wear or any kind of unusual markings. No sign of any kind of binding at all. The bearings are dinged just slightly where the shaft wobbled after breaking. Inside the crank break, it looks like tiny bubbles. Almost a sandy texture look and feel.

    I was not able to get information on the first break location from the first mechanic. So I am not sure about both breaking in the same place. The first break occurred while the unit was in idle. I went inside to get a drink and left it in idle. When I came back out after a few moments, it was dead and would not start. Second break, it was in idle as I stepped off to hook up 3 point. I got back on, raised speed slightly and put in reverse. Tractor lurched and died. I was never able to get it started again. I felt the same thing had happed again. It did.

    No leaks, coolant and oil levels all good. The flywheel and bell look good. No missing fly weights. The fly even has a hole bored for counter balance. No addition weights appear to have been added or thrown.

    I will ask the mechanic to do something to have the block checked for straightness between the crank main journals before reassembly. There are no obvious defects showing.

    I will try again to contact the first installer and see if I can get location of first break. I agree that is a critical piece of information that I would like to have also.

    Thanks for everyone’s input.

  8. #8
    Super Member kenmac's Avatar
    Join Date
    Feb 2005
    Posts
    5,481
    Location
    The Heart of Dixie
    Tractor
    yanmar 3110D

    Default Re: Broken Crank

    Inside the crank break, it looks like tiny bubbles. Almost a sandy texture look and feel.



    This would indicate to me that this is (mabe) a cast crank instead of a forged crank. Does anyone know if these cranks are forged or cast ?

  9. #9
    Gold Member
    Join Date
    Dec 2006
    Posts
    415
    Location
    Quebec
    Tractor
    Two Gravely Two L One with 10 h.p Dek-Diesel engine one Grillo 107d and one BCS 735 diesel

    Default Re: Broken Crank

    Hi! Everybody! My opinion. Is it not a crankshaft problem! Yanmar are direct injection engines. So Injection timing are very Important. Bads injectors (check opening pressure), bad injection timing pump. (Check advance and regulator timing)May be some Injector or bad injection pump( no the good one) Check every parts numbers with original OEM engine parts manual. So Check block! Dont fit new crankshaft before find the trouble! Good Luck! Oldmech

  10. #10
    Elite Member
    Join Date
    Mar 2002
    Posts
    3,310

    Default Re: Broken Crank

    Quote Originally Posted by oldmech
    Hi! Everybody! My opinion. Is it not a crankshaft problem! Yanmar are direct injection engines. So Injection timing are very Important. Bads injectors (check opening pressure), bad injection timing pump. (Check advance and regulator timing)May be some Injector or bad injection pump( no the good one) Check every parts numbers with original OEM engine parts manual. So Check block! Dont fit new crankshaft before find the trouble! Good Luck! Oldmech
    My thoughts exactly, pre-combustion on one cylinder could cause it, putting undue strain on the crankshaft. That's why I was curious where it/they broke. (Between the cylinders?)

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