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Water in crankcase drain tube - CB400

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by evman, Sep 29, 2015.

  1. So this morning I started my bike 2009 CB400 and noticed a bit a water had come out one of the 3 breather hoses on the right side of the bike (not sure which now), but didn't really think much of it as figured it was probably just some condensation. I then went for 15 minute drive, and noticed that my fuel gauge drop 2 bars to empty, hmmm I don't trust these gauges anyway I thought. After leaving the bike for an hour I came back home, and noticed a new but subtle noise from the engine, like a fast tapping. I filled up after about 10 minutes as I was apparently out of fuel, then got home. A little nervous about what was going on I decided to investigate the water some more, so I opened up the crankcase breather drain plug on the left of the engine and sure enough water came out, maybe 20 mL (it was more than could fit in the little tube itself). I can now hear a taping noise coming from the head of the engine, which may have been there before and I'm just being paranoid.

    Does this sound like water in the fuel? Or just some condensation? It's been raining all last week (bike is kept in cover at home).


  2. #2 Nicholai_Chev, Sep 29, 2015
    Last edited: Sep 29, 2015
    Thats a rather unique problem.
    Its possible you got some water through the bike from the rain, did you ever leave it outside or give it a wash over the weekend?
    Unless your routinely checking out your bike, water does build up in places like the airbox and locations with a drain plug in it.

    Contaminated fuel could cause a slight miss which would sound like ticking and get worse under load and generally make the bike run poor.
    Draining the tank and refulling with premium is a wise idea.
    Its not uncommon to amplify or tune into a noise you think is new when the bike is running less than ideal.

    If it sounds like top end ticking I would check your oil level and even do a quick change if you have some spare oil and feel kind.
    Oil changes always psychologically atleast make strange noises go away!
    • Like Like x 1
  3. It did get rained on last week once. It does seem to be running ok, but maybe its a good idea to chuck then fuel in the lawn mower and change the oil. Maybe as you say I'm hearing things that aren't a real issue.