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Thread: Oil Leak from exhaust base?

  1. #1
    Registered User
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    Apr 2003
    Location
    Stanardsville, VA
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    Oil Leak from exhaust base?

    Recently I've noticed oil collecting on the front and underneath the right cylinder of my '75 R75/6. I'm not positive, but it seems as though it's coming from where the exhaust comes out of the cylinder. This seems like an odd place for oil to be coming from and has me concerned as to whether this has a specific meaning.
    Obviously, the bike needs some work, as it seems to have oil leaks from many different parts of the engine. However, because I ride this bike significantly less, I have been putting off any major work, as it stilll runs fine for my commute and around home. I know I have to keep an eye on the oil level, but am unsure how much oil I go through. I want to say I have to add maybe a quart for every 1000 miles, but that's just a guess. Does that sound excessive?
    Anyways, if anyone has an idea of what may be going on with the oil around the exhaust base, I would appreciate your input.

    Thanks in advance.
    02 R1100SBX Prep
    93 K1100LT
    75 R75/6

  2. #2
    Rbike
    Guest
    A QUART EVERY 1K !!!!! Sorry to say but that is VERY excessive. Even being a quart low for every oil change is quite a bit. If all that oil was leaking externally you would certainly notice your bike "marking it's spot" as if it was trying to intimidate an old harley. But if you have an exhaust valve guide that is very worn, it can end up coming out of the exhaust port if too much oil is going into the combustion chamber to be burned.

    Look at your spark plug color. If you're burning that much oil the plug will be a slick blue black color. If it's clean (just some light tan) then you need to look further for the source of the leak. You may need to clean everything to get a good indication of where the oil is comming from.

  3. #3
    rocketman
    Guest
    Hmmmm, another possiblily is to check the valve cover gasket. Look for oil around where the valve cover fits, esp. underneith, also check to see if it could be the head gasket. The oil to feed the head is forced thru the upper 2 cylinder stud passageways, and since it is under pressure it will find it's way out any surfaces that are not flush, i.e. at the base gasket or head gasket.

    As for a quart every thousand miles, if it was burning it I'd say don't worry about it, for airhead that's really not much, esp. if it has 40K or more miles. In fact most air cooled motors tend to burn some oil. Leaking oil, on the other hand is deffinately an indication of a sealing problem somewhere. Remember that oil can creep so it can wind up looking as thou it's coming from one place when it's really coming from somewhere else. Clean the motor with some degreaser then keep checking till you see the first signs of oil, that will give you a good indication of where to start checking.

    RM

  4. #4
    Registered User
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    Apr 2003
    Location
    Stanardsville, VA
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    Thanks to both of you for the feedback. I hope to put aside some time this weekend to give the bike a good cleaning, check out the spark plugs, and see if the headcovers and/or cylinder themselves need to be tightened up. I'll report back what I eventually find out.

    Thanks again.
    02 R1100SBX Prep
    93 K1100LT
    75 R75/6

  5. #5
    Registered User
    Join Date
    Apr 2003
    Location
    Stanardsville, VA
    Posts
    33
    I've been dragging my feet on this. I checked the plug on the right cylinder and the tip was dry/tan, although there was a black/oily residue on the circumfrence/base and on the threads. Is this normal? I haven't made the time to give the bike a thorough cleaning, but I did notice that there is an oil residue on the cylinder guard/crash bar under the right exhaust base. I don't see how oil could get there from anywhere else.
    I failed to mention previously that I am hearing a new sound from this cylinder as well. The valve noise is louder, with a dull, muffled sound to it. Kind of hard to explain. 3 years and 14k miles ago I had new exhaust valves and guides installed. So I'm hoping it's not related to this, although anything's possible.
    I checked the valve clearance when I first started hearing the noise and didn't notice anything unusual. I must note that adjusting valves is something I am relatively novice at. If I were adjusting them wrong (would be on the side of too much clearance if anything) could this be causing the problem?
    Sorry for throwing out so many questions. I don't mind having to add oil ocassionally until I can get the problem fixed, but wouldn't want to keep riding the bike if I am potentially causing more damage.
    Thanks in advance.
    02 R1100SBX Prep
    93 K1100LT
    75 R75/6

  6. #6
    Rbike
    Guest
    Your spark plug coloring sounds correct...there is often a black oily look to the body of the plug, but if the tip looks that way then you have problems. So from your report and the fact that new guides and valves were put in I do not think your are burning the oil that you are adding.

    You now MUST do a very good cleaning job to be able to tell where the oil is comming form. Cleaning isn't on the top of my list of things to do, but to hunt down an oil leak it is a must. Just don't try to clean the engine while it is hot. Only clean it at room temperature. I like a product made by Castrol, I'm not at home to see what it is called but it is available at about any retail chain auto parts store and might be called Super Clean. You just can NOT use it on a warm engine...I cn not stress this enough as I trashed the appearance of a show engine I built when I put this stuff on it while it was warm. Cool, it doesn't do any harm and cleans excellent.

    Look around and you can find a variety of cleaning brushes, even ones that look like a toothbrush with brass wires.

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