Kubota D722 broken crank

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Tazza

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I got hold of an engine last week, a Kubota D722 3 cylinder. I was told its pretty new but it has broken the crank right on the center main, between number 1 and 2 cylinder.
Do these engines have a reputation for breaking cranks?. I don't understand how the crank could break like this. If anywhere, i'd expect it after number 3 where the fly wheel attaches, surly this is where the most load is applied, not the front like where it broke. The only thing i could think was it could have been a bad casting that had an air pocket or hair line crack or something.
If it snorted up some water from a cracked head i'd expect it to bend the rod or smash the piston, but it seems straight and the piston is fine.
Ideas?
Are these prone to cracking heads like the V1702 are?
 

sterlclan

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ive seen broken cranks in wierd places form crashing an impact on the balancer end sends shock waves through the crank and snaps themin strange places this is in a car or truck but the same would apply to equiptment what was it in? Jeff
 

skidsteer.ca

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ive seen broken cranks in wierd places form crashing an impact on the balancer end sends shock waves through the crank and snaps themin strange places this is in a car or truck but the same would apply to equiptment what was it in? Jeff
Could be just a fluke, poor casting etc, have to ask bobcat part manager or someone like that that deals with alot of these loaders. Have never heard of this anywhere else.
Some engines are know to break cranks (we had a 440a jd skidder do it twice in 5000 hours, poor design my conculsion)
Ken
 

Tazza

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Could be just a fluke, poor casting etc, have to ask bobcat part manager or someone like that that deals with alot of these loaders. Have never heard of this anywhere else.
Some engines are know to break cranks (we had a 440a jd skidder do it twice in 5000 hours, poor design my conculsion)
Ken
I too suspect its a fluke as where i get my spare parts for Kubota engines don't list cranks on their site. But they do list V1702 heads that are prone to cracking!!!
We have to make a few cals about it, i still don't know what i can do with a 18.8hp 3 cylinder engine... Then i need to try and adapt something to start the rotten thing to give it a test.
Thanks for the input guys
 

skidsteer.ca

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I too suspect its a fluke as where i get my spare parts for Kubota engines don't list cranks on their site. But they do list V1702 heads that are prone to cracking!!!
We have to make a few cals about it, i still don't know what i can do with a 18.8hp 3 cylinder engine... Then i need to try and adapt something to start the rotten thing to give it a test.
Thanks for the input guys
What was it out of? You found a crank for it? or you just scooped it up incase you found a home for it someday?
Most of these watercooled diesel could just be connected to a garden hose for cooling and started to a to test them out.
Ken
 

Tazza

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What was it out of? You found a crank for it? or you just scooped it up incase you found a home for it someday?
Most of these watercooled diesel could just be connected to a garden hose for cooling and started to a to test them out.
Ken
It was out of a Bobcat 463.
A second hand crank is $500!!!!!!! My dad made a few calls, i can't see anyone risking 500 on a second hand crank that still needs machining and you have no warranty, it could break like the one i have now.
The only reason i got it was because the price was very good.
As for testing, you can run these engines for small amounts of time without cooling, like say 30 seconds but i still have no way to even start it, i have no fly wheel or starter. I need a small fly wheel and starter off a car and make an adapter plate. Without a load it still tells me nothing even if i can start it.
My dad was prowling the Kubota web site and rekons that the D722 is the most popular engine they have made.
 
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