Massive oil leak

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davidprice
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Massive oil leak

Post by davidprice »

I have just completed a total engine rebuild on my B25SS. While it was up on the lifting bench I noticed oil leaking from the sump plate. When the sump plate was removed about 1/2 pint of oil came out. A new gasket fixed the leak, but when I took the bike off the stand and put it on its side stand, overnight, virtually all of the engine oil leaked out over the garage floor. It was not obvious where the oil had leaked from. What could I have missed out or reassembled incorrectly to end up with such a huge oil leak. It did not leak when the bike was upright though the sump may have been filling up.
Clearly something is not as it should be . Any pointers as to what I should look for to cure this would be greatly appreciated.
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minetymenace
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Re: Massive oil leak

Post by minetymenace »

Non-return valve leaking. Shouldn't leak out overnight, but will do in a month or so, which is normal. A search of the forum will suggest a few more things (oil punp, pipes not in correct position) the a search for "Wet sumping" for a start....
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mlb50
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Re: Massive oil leak

Post by mlb50 »

During the rebuild - by any chance did you miss fitting a new drive side crankshaft oil seal? As the bike leans over on the left, the sump oil (and its possible it is wet sumping) and possibly finds a gap between the crankcase and primary?
I did witness this on a mates Commando. Not pretty!
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Mr Mike
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Re: Massive oil leak

Post by Mr Mike »

The wet sump may well be faulty, however, there is a major leak to let the oil out of the cases. The faulty wetsump will allow the oil to go from the tank to the sump, but it should stay there. As mentioned before these bikes over a month or two have a tendency to drain the oil from the tank (or frame for OIF models) into the sump. My B50 does that if I don't start it for two or three months. Here what you should do: With degreaser and high-pressure water clean off all the oil on the engine and dry it off. Put oil in the tank Then put a clean newspaper under the bike and wait to see where the drip goes. With a flashlight and mirror trace the oil to where the oil is getting out. Once you find it drain out the oil and disassemble to correct the problem. I cannot think of anyplace that oil can leak out that fast unless there is a damaged or cracked case.

Mr Mike
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