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Author Topic: So I dropped an O-ring in the crank case. Opinions?  (Read 2001 times)

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Offline badfsh

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So I dropped an O-ring in the crank case. Opinions?
« on: August 29, 2015, 10:15:55 PM »
I am finishing up a rebuild on my 77 cb750k and last step was replacing the o-rings in the oil pump and checking clearances. As luck would have it I was removing the oring with my trusty pick when it popped out and right into the crank case. Looked everywhere to no avail. So question is do I have to pull the case apart again. I would prefer not to obviously. Any chance it will magically dissolve or float to the oil pan. All constructive opinions appreciated.

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Offline brandEn

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Re: So I dropped an O-ring in the crank case. Opinions?
« Reply #1 on: August 29, 2015, 10:52:43 PM »
I wouldn't sweat it. It will probably end up in the bottom of the oil pan sooner or later.
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Offline Retro Rocket

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Re: So I dropped an O-ring in the crank case. Opinions?
« Reply #2 on: August 30, 2015, 02:48:27 PM »
I would remove it, if it got chewed up in the gearbox or one of the chains I would not want little rubber pieces in my oil that could possibly end up in a blockage and engine failure. If you get it out, you don't have to worry.... I wouldn't leave it in there. It most likely will end up in the sump, but I just wouldn't risk it myself...
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Offline RevDoc

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Re: So I dropped an O-ring in the crank case. Opinions?
« Reply #3 on: August 30, 2015, 05:18:24 PM »
Quote from: Retro Rocket on August 30, 2015, 02:48:27 PM
I would remove it, if it got chewed up in the gearbox or one of the chains I would not want little rubber pieces in my oil that could possibly end up in a blockage and engine failure. If you get it out, you don't have to worry.... I wouldn't leave it in there. It most likely will end up in the sump, but I just wouldn't risk it myself...

+1  As RR pointed out, you could end up with little pieces moving with oil flow and possibly plug up an oil port and end up trashing your rebuild!
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Offline Don R

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Re: So I dropped an O-ring in the crank case. Opinions?
« Reply #4 on: August 30, 2015, 06:14:44 PM »
 There were a couple loose pieces of o ring (sleeve rings)  in my drag bike's engine, they were chewed and sticking to the screen but didn't do any permanent damage that I can find. Less of a problem than metal, It depends how much you love this engine.
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Offline Powderman

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Re: So I dropped an O-ring in the crank case. Opinions?
« Reply #5 on: August 30, 2015, 08:02:45 PM »
Could you drain the oil and then keep flushing the lower end with kerosene or something in hopes of flushing the ring into the oil pan?
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Offline Don R

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Re: So I dropped an O-ring in the crank case. Opinions?
« Reply #6 on: August 30, 2015, 10:31:37 PM »
 I clean the bottom of my oil tank with a copper tube taped in my shop vac hose, could something like that work? maybe some 3/8 OD copper, aluminum or chrome supply tube bent into a ? Even a rubber hose with a wire taped to it.
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Offline mrbreeze

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Re: So I dropped an O-ring in the crank case. Opinions?
« Reply #7 on: August 30, 2015, 10:50:15 PM »
Quote from: Powderman on August 30, 2015, 08:02:45 PM
Could you drain the oil and then keep flushing the lower end with kerosene or something in hopes of flushing the ring into the oil pan?
This is what I would do along with blowing compressed air from the top. Like Mick said you don't want bits of rubber plugging up oil passages. It sucks when stuff like this happens but I'd rather go through the motions and get it out of there than chance it coming out on it's own.
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Offline badfsh

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Re: So I dropped an O-ring in the crank case. Opinions?
« Reply #8 on: August 31, 2015, 09:18:23 AM »
Thanks for the advice. I split the cases and found the o-ring. It was sitting directly below the transmission. This project has been almost two years in the making and figured whats another day vs another rebuild.
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Offline SOHC4 Cafe Racer Fan

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Re: So I dropped an O-ring in the crank case. Opinions?
« Reply #9 on: August 31, 2015, 10:40:34 AM »
Good on you! That minor sidestep will give you some peace of mind.
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Offline PeWe

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Re: So I dropped an O-ring in the crank case. Opinions?
« Reply #10 on: August 31, 2015, 01:35:46 PM »
Better to do it properly and the little extra.
You will avoid future problems. Pulling engine again in and much more to repair is worse.
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Offline przjohn

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Re: So I dropped an O-ring in the crank case. Opinions?
« Reply #11 on: August 31, 2015, 02:49:15 PM »
Yup, good move. Piece of mind can be worth a few hours labor.
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Offline Restoration Fan

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Re: So I dropped an O-ring in the crank case. Opinions?
« Reply #12 on: August 31, 2015, 06:35:56 PM »
Quote from: przjohn on August 31, 2015, 02:49:15 PM
Yup, good move. Piece of mind can be worth a few hours labor.
+1  Very smart move, IMO.
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Offline 754

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Re: So I dropped an O-ring in the crank case. Opinions?
« Reply #13 on: September 01, 2015, 09:41:25 PM »
Yes it could end up in the top end.....but...
....but.. How could thecpieces be any bigger than the holes in the pump screen ???
 I think anything. Getting through the  screen would be tiny..
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Offline Retro Rocket

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Re: So I dropped an O-ring in the crank case. Opinions?
« Reply #14 on: September 01, 2015, 10:13:02 PM »
Quote from: 754 on September 01, 2015, 09:41:25 PM
Yes it could end up in the top end.....but...
....but.. How could thecpieces be any bigger than the holes in the pump screen ???
 I think anything. Getting through the  screen would be tiny..

But being small rubber pieces, they could accumulate on sludge or any imperfection in an oil gallery, better out than in, takes risk out of the equation... ;)
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Offline lucky

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Re: So I dropped an O-ring in the crank case. Opinions?
« Reply #15 on: September 02, 2015, 11:31:55 AM »
IF the clutch is not on yet you can easily see it through the hole in the cases.
Right side case.
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Offline Bodi

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Re: So I dropped an O-ring in the crank case. Opinions?
« Reply #16 on: September 04, 2015, 07:03:13 AM »
The oil system is pretty good at keeping crap out of the important places. Unfiltered oil does go to the transmission bearings but bearing and top end oil is filtered on the way.
Knowing a lump of rubber is loose, I would want to find it.
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