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Huge oil leak from crankcase vent

Discussion in 'Motorcycle Tech Talk' started by ogshortfatman, Nov 2, 2007.

  1. ogshortfatman

    ogshortfatman New Member

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    Ok- Back to the drawing boards....My bike has an s and s lower end, big sputhe barrels with 4.1 bore and 4 5/8 stroke, wellover 100 c.i. and hundred plus hp. It has vented rocker boxes(not the factory style head breathers, but actually vented rocker boxes) and it has the standard crankcase vent that would originally go to the carb but now is routed up and into a catch can (actually a 16 oz water bottle) that is mounted on the side of the frame about carb height or so. The problem is I keep dumping oil out of the crankcase vent big time. Not just a drop, dumping. I rode across town and filled the 16 oz bottle, I put in a quart in the oil bag(it was a bit low before that ride) and on the way home I filled the bottle again and them some. That is a quart in like a 5 mile ride. Before I put the quart in, it was low enough to where the dipstick was not hitting oil, LOW! I know the spring check valve sometimes lets the oil leak down, but this will not do it when I first fire it up, but once I am going a bit(mid-rpm's), and i just rode the bike yesterday and it only spit out a bit into the catch can then. Today a quart. :( I had all of the oil lines off of the bike, but I had this problem before with it and I still am having the problem. I am gonna check the check valve tonight/tomorrow, but I just dont think that is the problem, maybe so though. I thought I would ask again. Any ideas? Thanks in advance.
  2. mwelych

    mwelych Active Member

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    Not sure of this, but is there a chance that since you had the oil lines off, could you have possibly hooked them up backwards??? Just an idea...:)
  3. kenfuzed

    kenfuzed Administrator Staff Member

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    Are your plugs getting fouled/wet as well? I would double check those lines and make sure nothing is blocked.
  4. ogshortfatman

    ogshortfatman New Member

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    I am 99.9% sure lines are right and I had this problem before I stripped everything.....:gah: Dry normal plugs. Thank you guys! Any other ideas?
  5. ogshortfatman

    ogshortfatman New Member

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    Problem ended up being a sheared keyway after a tooth broke off of one gear on the scavenger side of the oil pump. The oil was not getting returned fast enough so it was backing up in the crankcase and then going where it could....so much fun. Later.
  6. FriendGregory

    FriendGregory New Member

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    Thanks for making sure we got the update

    This is very valuable information, I know stuff like this will keep us all riding.:)
  7. Dakota

    Dakota New Member

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    Yeh, thanks for letting us know what happened. It might happen to one of us someday and knowing this might help.

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