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914World.com _ 914World Garage _ Cracked crank
Posted by: jeffdon Jun 29 2014, 02:23 PM
Put my engine back together in November, and have been driving since then. Couple of 200 miles drives, mostly around town. Itts a 2056, webers, cam, nothing super high power. This weekend it started an awful clunk deep inside, and I got it off the road and towed home.
Got her puller apart, and here is what I have found. Crank broke threw the rearmost counterweight. How does this happen? So I need a new crank. What else should I replace? Obviously all main bearings. Rod bearings too?
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Posted by: jeffdon Jun 29 2014, 02:40 PM
Ok, 914 guy I know had me look the thrust surface of the flywheel end main bearing. Its chewed up, so maybe I f-d up my endplay?
Posted by: Jake Raby Jun 29 2014, 07:35 PM
Was the crank magnafluxed at assembly? That fracture appears to have been a long time coming based on the coloring around it.
Posted by: jeffdon Jun 29 2014, 10:02 PM
Was the crank magnafluxed at assembly? That fracture appears to have been a long time coming based on the coloring around it.
No, I admit to not doing that. The next one, for sure. Don't want to go through this again. I like to think I can build an engine to spec. Just seems I may have screwy parts. This time, i am going to get everthing checked out.
Posted by: Mark Henry Jun 30 2014, 07:05 AM
Most likely your case is trashed, get a new core.
If you F-ed up your endplay you should see signs of the counter weight hitting a main web.
Posted by: Matt Romanowski Jun 30 2014, 09:46 AM
I'd inspect the case before trashing it. I've seen a decent number of cranks break in different motors and not hurt anything (other than the crank).
Expensive and not fun way to make paper weights. It sucks when you have to add a second broken parts shelf to the garage.....
Posted by: jeffdon Jun 30 2014, 11:22 AM
I'd inspect the case before trashing it. I've seen a decent number of cranks break in different motors and not hurt anything (other than the crank).
Expensive and not fun way to make paper weights. It sucks when you have to add a second broken parts shelf to the garage.....
Looks like it hit the case. Marks that look like rough machine marks, but not even like machining. Deeper at the top. Is my case toast?
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Posted by: jeffdon Jun 30 2014, 11:38 AM
Was the crank magnafluxed at assembly? That fracture appears to have been a long time coming based on the coloring around it.
Jake - Regarding the coloring, I am not seeing any. I would think if I had tight endplay, and it got hot, I would see some blue/yellow somewhere. Could you expoind upon your color comment a bit?
Posted by: stugray Jun 30 2014, 11:41 AM
Due to the the poor lighting in the pics, it is hard to tell if that is corrosion inside the crack.
That would mean the crack was there for quite a while.
Although it is hard to tell in the pics.
Posted by: jeffdon Jun 30 2014, 01:12 PM
Due to the the poor lighting in the pics, it is hard to tell if that is corrosion inside the crack.
That would mean the crack was there for quite a while.
Although it is hard to tell in the pics.
No obvious corrosion that I can see.
Posted by: colingreene Jun 30 2014, 02:20 PM
I have a spare factory 2.0 crank if you need it let me know.
Posted by: jeffdon Jun 30 2014, 03:23 PM
I have a spare factory 2.0 crank if you need it let me know.
PM sent
Posted by: stugray Jun 30 2014, 04:07 PM
Youd be better off getting one of the complete crank, bearings, case that was for sale recently on the WTB: parts thread.
It was a great deal ofor ~$800 for all in a matched set.
http://www.914world.com/bbs2/index.php?showtopic=236879
Posted by: Valy Jun 30 2014, 04:39 PM
I'd inspect the case before trashing it. I've seen a decent number of cranks break in different motors and not hurt anything (other than the crank).
Expensive and not fun way to make paper weights. It sucks when you have to add a second broken parts shelf to the garage.....
Looks like it hit the case. Marks that look like rough machine marks, but not even like machining. Deeper at the top. Is my case toast?
Those marks will not trash the case. They don't look so deep that may cause structural problems.
However, you need to check the case bore. It looks to me that the bearing has some play along the crank axle, seen on the bearing seat in the picture. It might be just the camera but you better check.
Posted by: jeffdon Jun 30 2014, 09:55 PM
I'd inspect the case before trashing it. I've seen a decent number of cranks break in different motors and not hurt anything (other than the crank).
Expensive and not fun way to make paper weights. It sucks when you have to add a second broken parts shelf to the garage.....
Looks like it hit the case. Marks that look like rough machine marks, but not even like machining. Deeper at the top. Is my case toast?
Those marks will not trash the case. They don't look so deep that may cause structural problems.
However, you need to check the case bore. It looks to me that the bearing has some play along the crank axle, seen on the bearing seat in the picture. It might be just the camera but you better check.
They seem light-ish. I have another case. Guess I could send them both out and have a shop tell me which would be the best.
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