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V50/V35 Gear box seeps oil through top vent

Discussion in 'Small Block' started by Skivo, Feb 22, 2021.

  1. Skivo

    Skivo Tuned and Synch'ed

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    The parts breakdown doesn't show any valve stem seals for this bike. Maybe disassembly will show otherwise?
     
  2. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    It doesn't show any because Guzzi has never used them.
     
  3. Skivo

    Skivo Tuned and Synch'ed

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    So I'm back to the k-lines in that case?
     
  4. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    Yes.
     
  5. Adamigo

    Adamigo Just got it firing!

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    So, having two "stem sealed" heads on a ridden 1979 bike, I have taken a head off spare 1980 engine. What I have found?
    IMG_20210313_132546.jpg
    Now, if this is a home made improvement, the grove machined on the valve guide is there exactly to keep the seal in place, what means, must have been done first and then pressed in. IMG_20210313_133315.jpg
    The seals are CORTECO B15 V4-161, for 5.5 valve stem, 9mm guide diameter, 8.5mm high.
    Hey John, we learn something new every day, don't we?
     
    Last edited: Mar 13, 2021
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  6. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    Those seals aren't factory. They were added by someone. Some oil in the guide is good for lubrication. The K-lines have grooves to hold oil to lubricate the valve stem.
     
  7. Adamigo

    Adamigo Just got it firing!

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    Could be. But then an entire idea of stem seal would be wrong, as how to maintain oil presence in the guide if seal does what it says on the label. Then, with 66kmiles on the clock, I find my engine healthy enough to pull sidecar with no trouble. So, lack of oil in the guide isn't that lethal.
    You've mentioned "K-lines" several times, would you tell me what does it mean. Never heard of it before.

    Oh, I have dug a bit more in my spares, some of them new old stock, bought as a job lot years ago. I knew I could have another part of the puzzle: valve_guidesV50.jpg
     
    Last edited: Mar 14, 2021
  8. Skivo

    Skivo Tuned and Synch'ed

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    K-lines are valve guide "liners". See the installation video from SB, Intl:



    It takes some special equipment to install them.

    Maybe Guzzi went away from valve stem seals by 1979/80? Maybe the guides had grooves but they were using generic part sourcing and never needed or used the grooves? I'm taking my heads to a machine shop on Friday. I'll get them to check to see if my valve guides have grooves for stem seals.
     
    Last edited: Mar 17, 2021
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  9. Skivo

    Skivo Tuned and Synch'ed

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    Photos from head removal. The left head was not fully torqued down I discovered but the gasket was in good shape. The right side didn't have any loose bolts but the gasket may have been having an issue. A more seasoned eye might be able to make something from these photos.

    With due double valve spring setup (inner + outer) it doesn't appear there's any room in there for valve stem seals.
     

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  10. Adamigo

    Adamigo Just got it firing!

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    I can assure you, the room is there:) I gave you seal measurements, just check ID of inner spring.
     
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  11. V50iiix

    V50iiix Just got it firing!

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    These are standard to all V35-V75. GU19037820, replaces 61037801. Search and you'll find them on Gutsibits, Stein-Dinse, Harpers etc.
     
    Last edited: Apr 6, 2021
  12. Skivo

    Skivo Tuned and Synch'ed

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    I'm not familiar with Gutsibits or Stein-Dinse. Which would you suggest for someone on the West Coast (USA)? I'm done with Harpers if there's an alternative...
     
  13. Skivo

    Skivo Tuned and Synch'ed

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    You are correct, there is room. The machinist at the shop said my heads did have stem seal (and they need to be replaced). Worn exhaust valve guides as well...
     

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