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Broken Crankshaft on Kohler 25 HP on LT40 HYD

Started by DR_Buck, June 12, 2017, 08:34:50 PM

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DR_Buck

Today, with no warning I have had my most serious problem with my LT40 HDG25.   14 years, 954 hours and nothing close to this has happened.   The crank shaft on the Kohler 25 just gave out and snapped right off where it exits the engine.   

I can't even imagine what would make this happen aside from some kind of defect in the shaft metal.   Late last summer I replaced a failed drive belt, the first one, original to the new mill,  and installed a new one in it's place.  The drive belt tension was set to the correct tension using a gauge and everything has worked fine.   Until about an hour ago.....

Any fix is going to be expensive.   Either a new engine or complete rebuild of the old one, which I have no time to do right now.       Anyone have any ideas on what could have cause this?








Been there, done that.   Never got caught [/b]
Retired and not doing much anymore and still not getting caught

jmouton

maybe the metal was made from old dylithiom crystal metal,,,,,scottie might know
lt-40 wide ,,bobcat,sterling tandem flatbed log truck,10 ton trailer, stihl 075,041,029,066,and a 2017 f-350,oh and an edger

Magicman

Knothole Sawmill, LLC     '98 Wood-Mizer LT40SuperHydraulic   WM Million BF Club Member   WM Pro Sawyer Network

It's Weird being the Same Age as Old People

Never allow your "need" to make money to exceed your "desire" to provide quality service.....The Magicman

DR_Buck

Obviously, I need to get this fixed so I need to look at options.     Has anyone replaced the Kohler 25/28 Command Pro with the Kohler  35 HP V-Twin?   More HP is not a bad thing.
Been there, done that.   Never got caught [/b]
Retired and not doing much anymore and still not getting caught

GDinMaine

It seems like the result of 954 hours of operation under side load. WM came out with an add-on part that serves to support the end of the drive shaft on certain engine models. I know this does not help you much, but it appears this is an issue on mills powered by other engines as well.
It's the going that counts not the distance!

WM LT-40HD-D42

Magicman

I wonder if WM is offering the "crank kit" for the smaller engines to prevent this in the future?

Here is what WM has listed as replacement engines:  LINK
Knothole Sawmill, LLC     '98 Wood-Mizer LT40SuperHydraulic   WM Million BF Club Member   WM Pro Sawyer Network

It's Weird being the Same Age as Old People

Never allow your "need" to make money to exceed your "desire" to provide quality service.....The Magicman

DR_Buck

Quote from: Magicman on June 12, 2017, 09:19:57 PM
Here is what WM has listed as replacement engines:  LINK


I saw that.   There is nothing showing replacing the 25 HP Kohler with the 35 HP V-Twin.    I might have to make a call tomorrow.
Been there, done that.   Never got caught [/b]
Retired and not doing much anymore and still not getting caught

Peter Drouin

Wow, not good, A new motor will be a lot of $$
954 HRS is not much time.
A&P saw Mill LLC.
45' of Wood Mizer, cutting since 1987.
License NH softwood grader.

sealark37

I would check the small engine parts distributors for a price on a new crank.  You will need engine serial number, model number, and possibly an arrangement #.  It might be big bucks, maybe not so much.  Regards, Clark

POSTON WIDEHEAD

Will the crank still turn?
I was wondering if something locked up and made it snap.
The older I get I wish my body could Re-Gen.

captain_crunch

my thought why nother bearig  on end That lots of load on  Shaft
M-14 Belsaw circle mill,HD-11 Log Loader,TD-14 Crawler,TD-9 Crawler and Ford 2910 Loader Tractor

Brucer

That certainly looks like fatigue failure. In other words, it wasn't caused by a sudden overload. Side loading will cause the sort of stress that leads to fatigue, but in theory the manufacturer (WM) would have kept the side loading below the fatigue limit. However ...

Fatigue failure has a statistical component to it. Most will not fail but a few will. 2580 hours on mine and not a problem (but I'm sure going to take a closer look at the 2600 hour service).

Bruce    LT40HDG28 bandsaw
"Complex problems have simple, easy to understand wrong answers."

Kbeitz

I have no idea if it's the right model but E-bay has a 25 HP Kohler crank for sale
for $100.00 right now.
Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

DR_Buck

Quote from: POSTONLT40HD on June 12, 2017, 10:24:01 PM
Will the crank still turn?
........

    Still runs great.    Just no way to apply any load to it.    :-\   


Quote from: sealark37 on June 12, 2017, 09:46:48 PM
I would check the small engine parts distributors for a price on a new crank.  You will need engine serial number, model number, and possibly an arrangement #.  It might be big bucks, maybe not so much.  Regards, Clark

Quote from: Kbeitz on June 13, 2017, 03:25:03 AM
I have no idea if it's the right model but E-bay has a 25 HP Kohler crank for sale
for $100.00 right now.

  As of right now there is almost zero chance of me taking the time to rebuild it.  I may throw it into a corner for a future project.    I am seriously looking into seeing if I can up-size to the 35 HP Kohler.    I am calling Wood-Mizer this morning. 
Been there, done that.   Never got caught [/b]
Retired and not doing much anymore and still not getting caught

ladylake



  Don't hear much about Kohler cranks breaking, maybe just a bad one.  I think you can get by with running the belt a little looser on a gas motor compared to a higher HP diesel.  Does WM have different specs for the belt tension between lower HP gas and higher HP diesel motors, if not they should.  Steve
Timberking B20  18000  hours +  Case75xt grapple + forks+8" snow bucket + dirt bucket   770 Oliver   Lots(too many) of chainsaws, Like the Echo saws and the Stihl and Husky     W5  Case loader   1  trailers  Wright sharpener     Suffolk  setter Volvo MCT125c skid loader

Chuck White

Won't help you now DrBuck, but maybe for us that have this same engine, it wouldn't be a bad idea to mount the alternator on the other side of the engine in order to take some of the side pull tension off of the crank shaft!

I know there are different tensions, but right now, both the blade drive system and alternator pull sideways the same direction!

Just sayin!
~Chuck~  Cooks Cat Claw sharpener and single tooth setter.  2018 Chevy Silverado and 2021 Subaru Ascent.
With basic mechanical skills and the ability to read you can maintain a Woodmizer  LT40!

SineWave

Just for grins, I'd ask Kohler about it. Seems to me you should be able to get more than 1k hours out of it, even with extreme side loading, before fatigue failure.

And if Kohler says "Boo," then I'd ask WM about it.

Seems to me that if it's not defective, and less than 1k hours is all that one can expect, then some engineer somewhere needs to answer for this.

I'd raise hell about it.

TKehl

Have only done a bit of failure analysis, but I agree, looks like side load fatigue.  I don't see a rotational component in the fracture and it should be more jagged if it were a one time impact/overload scenario. 

As per SineWave's comments, I agree and disagree.  From a personal basis, it seems like it should last longer, and this one is probably statistically early as Brucer pointed out.  From the manufacturers point of view, how many of these (similar engines) are on lawn mowers, generators, and personal equipment that won't even see 1k hours over the life of the equipment.  If the failure rate is low enough, any extra $ put into design is a cost without return.

Still sucks.   :(
In the long run, you make your own luck – good, bad, or indifferent. Loretta Lynn

Kbeitz

Collector and builder of many things.
Love machine shop work
and Wood work shop work
And now a saw mill work

paul case

Chuck,
I believe his alt is on the opposite side. They changed it somewhere around 96?

PC
life is too short to be too serious. (some idiot)
2013 LT40SHE25 and Riehl edger,  WM 94 LT40 hd E15. Cut my sawing ''teeth'' on an EZ Boardwalk
sawing oak.hickory,ERC,walnut and almost anything else that shows up.
Don't get phylosophical with me. you will loose me for sure.
pc

Beavertooth

I had a 1988 model LT40HD with a 24hp Onan engine that I changed out to a 38hp Kohler. I talked to Greg at Woodmizer and he told me what to do. All it required was shimming up the new engine 1 inch and putting a different length belt on it. I had to custom fit the guard over the alternator belt and that was all it was to it.
2007 LT70 Remote Station 62hp cat.

Beavertooth

Just remembered that I did not order the new engine from Woodmizer and I had to order it with something different about the crankshaft. I remember it was $200+ for a kit to make it longer or different diameter. Not sure which one. That has been 9 years ago. So since it was farther back than yesterday my memory a little fuzzy on it.  :-\ :-\
2007 LT70 Remote Station 62hp cat.

DR_Buck

Ordered the 35 HP Kohler from Wood Mizer this morning.  With the install kit it was real pricey.   ::)
Been there, done that.   Never got caught [/b]
Retired and not doing much anymore and still not getting caught

Chuck White

Quote from: paul case on June 13, 2017, 09:18:19 AM
Chuck,
I believe his alt is on the opposite side. They changed it somewhere around 96?

PC

I just replaced the 24hp Onan on my mill with a 25hp Kohler two years ago, and the alternator belt pulls in the same direction as the blade drive belt!

Never did make sense to me, even changing the oil filter, I have to be careful not to spill into the alternator!
~Chuck~  Cooks Cat Claw sharpener and single tooth setter.  2018 Chevy Silverado and 2021 Subaru Ascent.
With basic mechanical skills and the ability to read you can maintain a Woodmizer  LT40!

ladylake

Quote from: DR_Buck on June 13, 2017, 01:11:07 PM
Ordered the 35 HP Kohler from Wood Mizer this morning.  With the install kit it was real pricey.   ::)

  You'll like that extra power and torque.   About right for a 1 1/4" band.   Steve
Timberking B20  18000  hours +  Case75xt grapple + forks+8" snow bucket + dirt bucket   770 Oliver   Lots(too many) of chainsaws, Like the Echo saws and the Stihl and Husky     W5  Case loader   1  trailers  Wright sharpener     Suffolk  setter Volvo MCT125c skid loader

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