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HELP - Fuel coming out of Rocker Cover breather tube

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by brindley, Dec 2, 2007.

  1. I have just brought a '84 Suzuki 750 Katana. I've had it for a couple of days and it was running fine, however this morning i went to start it and dirty fuel came pissing out of the rocker cover breather tube while the engine is running and I don't know why. Any ideas?

  2. Hi mate :)
  3. the bits highlighted in bold are a great clue
  4. Forgive my ignorance but clue for what?

    The fuel in the tank is clean and I just put it in the other day.
  5. If it came out dirty then there is a problem isn't there?
    Just because you put in new fuel doesn't mean that fuel is necessarily clean.
    Please fill in your profile, add more information about the type of fuel where you bought it, the state of the engine blah blah blah.
    Maybe when you add more information someone may help you more.
  6. ditto to what smee said, and tweet nudged :)

    You may well have put clean fuel in the tank, but unless the tank was bone dry and clean before you did so, you have no guarantee that dirty fuel won't come out.

    And I'm at a loss to know how dirty FUEL could come out of the rocker cover breather tube; surely that would be oil? And it if IS, then you have a blockage somewhere in the oil gallleries and a trip to a mechanic would seem to be your most reliable course of action. I certainly wouldn't be riding it under these circumstances, if only for the fact that whatever's leaking could end up under your back tyre......
  7. Thanks hornet600 for your response.

    It is definitely fuel coming out the breather tube, however I believe it's mixing with the oil in the rocker cover which is why it's coming out dirty.

    I thought it might have been something to do with one of the inlet values not closing properly however when the engine is running, it's not missing or knocking, which i would've thought would happen if it was the value.

    any trouble shooting processes would be appreciated.

  8. for fuel to be entering the cavity beneath your rocker cover, you have a serious failure in there. could be anything, most likely dropped a valve or similar, but whatever it is, it sounds as though it is f*cked ;)
  9. Ernest, some pictures would help :).
  10. As you probably know, the Breather Tube is attached to the top of the Rocker Cover and normally is connected to the airbox. However, the previous owner changed the air filters, so now the breather looks like it just sits there attached to nothing.
  11. [/img]


    Here are some pics, don't think they will show you much.
  12. You're right, they don't!

    Have you checked your oil? Whatever comes out of the rocker breather tube will also be flowing around in the crankcase. There is no way for fuel to get from the intake manifold into the rocker/valve area except via the crankcase.

    If fuel has leaked into the crankcase via an overflowing carb or vacuum valve fuel tap it would have seriously thinned out the oil. Better check your oil...

    No engine malfunction could get fuel above the cylinder heads without it also being below.

    All the best

    Trevor G
  13. Hi guys

    Good News...well for me anyway.

    I believe I fixed it after doing some research on the net.

    After buying the bike i went on holidays for a week and left the fuel tap in the on position. Somehow, and I don't know how, fuel continued to leak into the engine and down into the sump. When I came back from holidays, when I went to start it, it's belly was full of fuel and therefore pushing it up to the overhead cams and spitting it out the breather tube.

    This morning I drained the sump, (it had 5litres of oil and fuel) and then just now I put the oil back into it, started it and no probs....well so far.

    I would like to thank those that took the time to lend me their guidance and wisdom, however I do have one last question which I will post as a new thread.

    Hopefully this helps others out there that may experience the same problem.

    Thanks from,