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Discussion Starter #1
Tonight, I was doing some mowing down in some lowlands on my property with my freshly rebuilt L8, doing great, had the sulky on the back, flying through it like nothing! Green vegetation about 4' tall. All of a sudden I hear the worst sound you could hear, at first I thought I hit something metal with the brush hog, but it turned out to be much worse. The engine free revved for a split second then completely locked up in an instant. Mower slowly came to a hault.
Im guessing it was the lower rod bearing that let go due to all my oil pressure issues when I first rebuilt it. ( think it had oil pressure issues before I rebuilt it, that were let go for a long time, the reason for my front planetary issues)
Is there any chance that it could have been the rear planetary set? Im guessing not, because the machine free wheels fine.
This is the first time in my life I have had to tow a gravely back to the shop.
:thSick:
 

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Sorry to hear about your loss. Not to sound like a smart arse...but did you check the oil before you started running it?

I always check the oil before I touch the key on any of them. They're in a Garage, and you can see if they are leaking, but I still check.

Matt
 

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Probably not enough attention is given to the bottom ends of our old Gravely L's. There are situations where the main bearing can accumulate crud and provide a false pressure reading. It's probably a good idea to go through the motor's bottom end whenever the top end is redone.

I would agree with you that it sounds like a motor problem and not a tranny issue. Might as well just commit to pulling the engine off her - when you've got the stomach, maybe start by just removing the head and checking for damage. Either way, a serious bummer - especially when you're mowing along, all's well and then boom...disaster.

I certainly feel for ya on this one. Just get her diagnosed and get back in the saddle as quickly as you can! :banghead3
 

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Even the best machine can break, this is why alot of us become Gravely Horders, you just never know when you'll need something. Good luck with the repairs. :praying:ED
 

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Probably not enough attention is given to the bottom ends of our old Gravely L's. There are situations where the main bearing can accumulate crud and provide a false pressure reading. It's probably a good idea to go through the motor's bottom end whenever the top end is redone.
This is extremely accurate... for the most part everyone does "top-end rebuilds. That is not smart especially with the age and hours accumulated on most of our machines. :thanku:
 

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Discussion Starter #6
Yeah, oil level was perfect.
If it didnt trash my brand new top end, ill be happy. The main problem will be finding a GOOD crank to put in her. Not sure if I have the cash for a new one from Richards right now. Im getting married in October, not sure ill have time to fix her for a while, ill be moving into an apartment after that, no use for a gravely there! Luckily my parents live 10 minutes away so I can come work on it anytime.
 

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Tonight, I was doing some mowing down in some lowlands on my property with my freshly rebuilt L8, doing great, had the sulky on the back, flying through it like nothing! Green vegetation about 4' tall. All of a sudden I hear the worst sound you could hear, at first I thought I hit something metal with the brush hog, but it turned out to be much worse. The engine free revved for a split second then completely locked up in an instant. Mower slowly came to a hault.
Im guessing it was the lower rod bearing that let go due to all my oil pressure issues when I first rebuilt it. ( think it had oil pressure issues before I rebuilt it, that were let go for a long time, the reason for my front planetary issues)
Is there any chance that it could have been the rear planetary set? Im guessing not, because the machine free wheels fine.
This is the first time in my life I have had to tow a gravely back to the shop.
:thSick:
Very common for the rear planeyarys to go bad on the Kohler 16 HP powered units. Not as common on the Ls but it does happen. Bolts in them do shear. The tractor will still roll if the rear is locked up. But not if the front is.
 

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Discussion Starter #8
Ahh that makes sense, because when the front was locked up it didnt roll.

I guess there is still a little hope... but I was thinking on my way to work, bluegoose said that the lower rod bearing can clog, and cause a false oil pressure reading, does this mean that the oil line going into the bottom end goes into a crank journal instead of just spraying a mist into the bottom end? If so, this would make sense because it probably would have been full of metal particles from the first time it blew up, etc.
 

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The Model L crankshaft is made up of five pieces, assembled in this order: drive pinion shaft (with bushing), front flywheel, crankpin (with connecting rod), rear flywheel, and timing pinion shaft. Roger Beno has posted some great pictures at the yahoogravelyclub in an album titled Roger's Gravely Pics, last modified August 21, 2010. The pictures show the crankshaft components and the oil path. Here's a link to the photos:

http://groups.yahoo.com/group/gravelyclub/photos/album/1704450543/pic/list
 

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Outstanding pics/explanation by Roger. My understanding is that the pressure reading reflected on the gauge is taken at the entry point to the crankpin assembly. So if there was some accumulation of gunk, the gauge reading might not accurately reflect that. A friend of mine from Ohio that formerly worked on L's extensively said that he'd encountered few bottom ends that he hadn't observed blockage in - but that said, hadn't seen a tremendous number of failures either.
 

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Discussion Starter #12
tore the ol' lady down tonight.
turns out it was the oil pump shaft. The shaft sheered clean off, and sent the gear whizzing around the crankcase.
Crank looks to be in OK condition, but will have to examine further.
 

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Well that is a relief to know that it wasn't the crank shaft itself. I hope that it didn't starve the engine of oil for too long.
 

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tore the ol' lady down tonight.
turns out it was the oil pump shaft. The shaft sheered clean off, and sent the gear whizzing around the crankcase.
Crank looks to be in OK condition, but will have to examine further.
If you're able to determine how that sheering occurred, I'd be interested in hearing that info. Don't believe I've heard of an L engine failure of this nature before.
 

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Discussion Starter #15
For sure. I will take pics, and take a closer look as soon as I can. I wanna get this thing going asap.
 

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Discussion Starter #16
Here are some pics for yall to study:
The piston had more wear than I though for only having 4 hours on it. A little concerning


will the crank slide out of there as is, or do I have to remove anything else?



crank still looks and feels ok..



some carnage:



oil pump shaft sheered right off:





poor ol' thing:

 

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Since you have it this far apart split the flywheel and you will find an oil grove under the conecting rod make sure that it is clean or you will wreck the crank i have taken two of them apart and both have had muck caked in the grove it is from people not changing the oil often enought
 

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Discussion Starter #18
gahhhh I hate not being able to edit posts! This was meant to be the last pic.



thanks for the info, how hard is it to get the crank apart?
 

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You need a 20 ton press and push the centre out. You do not need to undo the screw but you will have to support the flywheel snd it will push down
 

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Dang, You've got her tore down...be a good time to clean the old thing up while you've got it this far apart, though! It looks like a pretty clean unit. Good luck getting it back together, I've never had mine tore down yet..I'd say it's fun.

Matt
 
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