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I wanted to ask for some advice. My ’46 Flathead was running fine until today. I started the bike and as soon as it fired up it dumped a lot of oil from the relief pipe. I haven’t done any recent work on the engine, so we can rule out that I assembled something incorrectly right now, it just suddenly decided to dump the oil out of the relief pipe.
I tried starting it a second time and the same thing happened: lots of oil coming out. Out of curiosity, I added more oil and started it a third time. This time, it only threw out a stripe of oil and then just a few drops every now and then.
Is it normal for these bikes to accumulate oil in that area? What could be causing this behavior?
It is called sumping. The check valve on your oil pump is supposed to keep the oil in the tank. With age all things wear out, oil begins to migrate into the engine cases. Ride the bike everyday, it will not happen Once a year, it will likely happen. Now you know, leave her sit for a long time and put a pan underneath before you start her up.
PS this is why you check the oil when hot, if you check cold after sumping, you will get a low reading, Then you start her up and start circulating the oil and the tank is over filled.
My bikes really do not sump, unless you let them sit. Had an accident with the Shovel 2 years ago, she was on the lift for 11 months. Glad I had the pan under her the day she got started back up. But under normal use, you should be good. Ride them every day, and likely never have an issue.
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RELIEF PIPE OIL DUMP!
