/6 pushrod tubes outside seal

Discussion in 'Old's Cool' started by mfp4073, May 9, 2011.

  1. mfp4073

    mfp4073 Long timer

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    Seeing the other thread I figured I would finally post this. I am getting dribbled/sprayed on from my right jug. Right on top of my foot but only when running (does not drip and leave oil on the ground).

    its damp under there, replaced valve cover gasket since its right in that area. In looking at the parts sites I dont see an outer seal and also saw it mentioned in the other thread that the outside is possibly interference fit. Also, anyone have a diagram/dissembled pictures. In looking under its hard to tell exactly where the tube terminates.

    THANKS!!!
    #1
  2. Xcuvator

    Xcuvator Justa Venturer

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    The only way I know of to find the source of a leak is to clean everything up real well, then ride the bike and stop often to see the first signs of oil. I have been fooled before, it doesn't take long for the oil to migrate.
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  3. Horsehockey

    Horsehockey A GPS? Huh?

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    As noted above, you should clean the right side of the engine case of oil and dirt. Then spray the area with spray foot powder or baby powder. Then take it for a ride. The powder will expose the source of the leak. My guess is the oil is dripping off the bottom of the right side airtube and/or collecting on the bottom of the float bowl. Oil collects there because your crankcase breather sends oil mist to your right side carb via the tube and some of that oil leaks out at the bottom of the airtube where it mates with the carb. Entirely normal.
    #3
  4. mfp4073

    mfp4073 Long timer

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    I promise its not coming from the intake tube/carb. The carb is dry all the time and it would have to travel forward in the air stream to get to my boot. It only happens at speed. There is oil on the bottom fins of the jug. Outboard of the area where the exhaust comes in, but inboard of the valve cover/gasket. Also, the outside of the peg rubber gets some on it too.
    #4
  5. mfp4073

    mfp4073 Long timer

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    Picture taken after 10 min of riding. Note its on toe and does not get on pants or uppers of my boots.

    [​IMG]
    #5
  6. Horsehockey

    Horsehockey A GPS? Huh?

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  7. Grider Pirate

    Grider Pirate Long timer

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    The tubes terminate at the top of the CYLINDER. The oil passage from the cylinder to the head is sealed by the head gasket. The tubes are an interference (tight press) fit into the cylinder.
    Whenever I get oil on the toe of my boot, it's the rocker cover gasket. If your rocker covers have been habitually over-tightened by previous owners, they will distort and not seal. Removing the rocker cover and then pulling the studs and checking/resurfacing may help. In my case, the leak is usually caused by using cheap-ass aftermarket rocker cover gaskets.
    #7
  8. mfp4073

    mfp4073 Long timer

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    Grider,

    Thanks for the reply! Got me some info there I was needing. I dont suspect the rocker/valve cover gasket anymore. I replaced it with a new one and a good one (from huckys, he dont sell cheap crap). Same results. Also, its dry that far outboard.

    Took a picture. The wettest part is between the red lines. And again, does not drip when sitting still. So I am thinking its got to be only when there is oil pressure and is not accumulating/dripping. Those interference fit pushrod tubes seem like they could be a culprit if you agree that they terminate in the area shown.

    [​IMG]
    #8
  9. Grider Pirate

    Grider Pirate Long timer

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    I think that kinda puts it back in the 'other' (pushrod tube in the head) http://www.advrider.com/forums/showthread.php?t=685835
    thread area. A couple of the 'old wise ones' have commented that the tube pressed into the head can leak. I have less experience, so I've never seen that happen. I sure can't think of anywhere else your leak could be originating! (Okay, maybe the rocker cover center stud on the head side??? I kinda' don't think that can happen, but.......)
    #9
  10. mfp4073

    mfp4073 Long timer

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    yeah, read through that, but since his was a 92 and mine a 74, I was not sure if anything had changed in all those years. I dont suspect the stud since its sandwiched in the gasket.

    Hopefully someone with a little more know will drop in. I REALLY DONT want to deal with replacing the tube and the interference fitting aspect. But its messing up my boots and tracking oil in the house.
    #10
  11. Boxer Metal

    Boxer Metal Mad Scientist

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    Going out on a limb here. On an old Boxer your foot is under the carburetor and the breather hose runs through the right air tube. If it's a high mileage motor maybe it's blow by leaking between the air tube and the carburetor.
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  12. mfp4073

    mfp4073 Long timer

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    Good thought, but that area is dry. Furthermore a leak at the carb or the carb mounts (rubber heater hose) would all be vacuum leaks, not blow out.
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  13. Boxer Metal

    Boxer Metal Mad Scientist

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    Nope. You have a breather hose that vents the crank case and goes right into to air tube pre carburetor vacuum.
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  14. mfp4073

    mfp4073 Long timer

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    The vacuum of the motor drawing the air in goes all the way to the air cleaner. The crank vent does not pressurize one side....unless I am getting so much blowby to create a supercharger effect! Its a scavanging effect of the motor pulling fresh air in and pulling vapor from the crank case with it. Unless BMWs are very different from everything else I have ever worked on......well let me take that back....
    #14
  15. Boxer Metal

    Boxer Metal Mad Scientist

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    To rule all of this out pull the air tube and clean it out really well. Put it back on the bike and see if your still get oil on your boot:D
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  16. mfp4073

    mfp4073 Long timer

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    LOL, could do it easier by just pulling the intake runners and going for a ride! (and hope no birds fly in there)
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  17. Xcuvator

    Xcuvator Justa Venturer

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    I have seen oil migrate to the area you indicated from other places. That seems to be a natural place for it to go.

    But if you have a bad tube:
    IMO the key to changing the pushrod tubes is having a drift punch of just the right size and good solid support for the cylinder. I turned a punch down from some brass round stock and made a collar for the bottom of the cylinder from 1 1/8" plywood. Sometimes the tubes come out with two or three whacks with a dead blow hammer and sometimes a little heat is needed.
    #17
  18. Boxer Metal

    Boxer Metal Mad Scientist

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    I good friend of mine did that and it back fired through the carb and caught the garage on fire. So I'm a little paranoid about doing that. Plus if you clean the tube and stick it back on you will have an idea of how much might be coming from the breather if any.
    #18
  19. mfp4073

    mfp4073 Long timer

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    #19