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Sudden appearance of oil leak from top of engine

Discussion in 'Stelvio Chat & Tech' started by scottmastrocinque, May 7, 2020.

  1. scottmastrocinque

    scottmastrocinque Scott Mastrocinque GT Famiglia

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    I recently developed a oil leak predominantly on the left hand side of my engine. I discovered the problem and solution so I offer the information here in the event you develop the same.

    I noticed a drip of a few oil drops on the garage floor. Upon inspection, oil was lightly all over the underside of the left cylinder head and it initially looked like the beginnings of a failed head gasket. I cleaned it off to see if I could better locate the source of oil.

    After a 500 mile ride, the oil had returned to the underside of the left cylinder as well as towards the rear of the engine in the left side. I also noticed spritzed oil on the right hand side of the engine now as well.

    So, I removed the tank, where I discovered the crankcase vent tube, after 8 years of riding here in Ohio winters and summers, had become stiff and brittle on the end, and the crankcase vent end of the hose was simply pushed onto the metal crankcase vent tube. Given its hardened condition, it was no longer tight on the tube, and in fact, had blown off for the most part.

    The oil was from the oil saturated air passing out the crankcase vent tube which had covered the underside of the fuel tank and all the wires and hoses, with a fine misted oil which had dripped and run all over the left cylinder, giving the appearance of a blown cylinder gasket. (You can see the fine mist of oil on the left intake tract in the lower left of the photo.)

    I cut 1 cm of the brittle end off of the crankcase vent end of the rubber “U” hose (the center tube going down the silver metal bracket), reseated it and crimped an Oetiker clamp on it. I then put another Oetiker clamp on the other end of the “U” hose where it connected to the air-box intake on the left (seen in the photo).

    I checked the inside of the air-box and there was no oil. (This BTW, is why you must not overfill your crankcase, because the liquid oil will be blown right into the air-box via this hose setup!)

    Everything is fine now. No more oil leak. Some degreaser and a good wash, and it’s just like new again!

    If you develop a similar oil leak, you might want to check this location.

    06B023FA-79AE-47FA-BDB8-EC20BF8E2A7C.jpeg
     
  2. Raven

    Raven Cruisin' Guzzisti GT Famiglia

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    I just replaced these on the right and left of my Norge. I tried cutting a small piece off late last summer and by the end of the season the hose on the left had split again and started leaking.
    This is a very common issue. Apparently Moto Guzzi used a type of rubber hose which does not stand up well to heat and oil.
     
    V700Steve and Bill Hagan like this.
  3. john zibell

    john zibell Moderator Staff Member GT di Razza Pura

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    Poor quality rubber components have been an issue with Moto Guzzi forever. Why do you think there are so many Italians? Bad rubber.
     
  4. scottmastrocinque

    scottmastrocinque Scott Mastrocinque GT Famiglia

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    Oh John, as an Italian-American, I say that’s a damn funny joke! :D

    But in defense of Moto Guzzi, 9 years of life from a rubber hose, is pretty good. I should just overhaul and replace the hoses all around. :nerd:
     
  5. John Warner

    John Warner Cruisin' Guzzisti GT Contributor

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    As mentioned, fairly common.
    A common fix is to cross new Hoses over, so the L/H hose goes across to the right, then forwards to the Collector, and vice-versa.
    It means you don't need such a tight bend in the Hose where it joins the Head Fitting.
     
  6. scottmastrocinque

    scottmastrocinque Scott Mastrocinque GT Famiglia

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    I'm not sure what you are saying here, as the left hand hose connects to the hose bib of the crankcase vent, just inches away. What difference does left or right one from the airbox make, as they are side by side and only inches away? :shake:
     
  7. John Warner

    John Warner Cruisin' Guzzisti GT Contributor

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    Sorry Scott, should have clarified it a bit better.
    The 'Mod' is to take the left Hose, from the Cylinder Head Stub, across to the right side of the Bike, then forwards and up to the Collector.
    The right Hose goes across to the left side, etc . . .
    This avoids the sharp bend in the Hoses near the Heads.
    [​IMG]
    [​IMG]
    Lower Hose here is the L/H one crossing over and going up the R/H side of the Bike.
    Upper one is the R/H Hose . . .

    There is another mod which uses Banjo hose Fittings at the Head Outlets.
    [​IMG]
     
  8. nomad

    nomad Tuned and Synch'ed

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    Can you add the pictures please, I am having similar problems with my 08 Stelvio
     
  9. saffermoto

    saffermoto Just got it firing!

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    Hi Scott also checked out Raven's Griso posts, this is where the oil 'sweats' from on my 2011 NTX. Looks like it's coming from the left side cylinder head breather. See pic. Any thoughts?
     

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  10. John Warner

    John Warner Cruisin' Guzzisti GT Contributor

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    Apologies for the late reply Nomad, don't come here that often now.
    I don't have the photos I'm afraid, they were lifted from another Forum.
    I'll try and find them again, but it's very simple really.
    Instead of the R/H Hose coming off the Head, doing a 180° tight turn, and going up the R/H side of the Frame, you take it from the Head, and route it across to the inside of the L/H Frame Rail, then up to the Separator/Condenser Box.
    Do the opposite with the L/H side.
    Breathers.jpg
    Obviously, you make the Bends as gradual as you can, just route them as required, up to the Condenser.
     
  11. scottmastrocinque

    scottmastrocinque Scott Mastrocinque GT Famiglia

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    Sorry I just saw this.

    I’ve not seen a leak from there. I am doubting that it is actually coming from there because the Oetiker clamp is a solid connection unless the tube itself is cracked, and the cover bolted to the side of the head has a huge o-ring in it if I remember correctly and it only holds back positive crankcase air pressure only, no liquid.

    I would check that hose for cracks and if I could find none, then wash with degreaser, and then sprinkle baby powder (corn starch) and go for a ride. Then sprinkle some more when I came back to see the real source of oil.

    Have you removed the tank and inspected yet?

    Good luck.
     
    Last edited: Sep 23, 2020
  12. John Warner

    John Warner Cruisin' Guzzisti GT Contributor

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    Scott.
    I've just re-read your original post, and took another look at the photo.
    One of the two Hoses, is the 'feed' from the Airbox to the Idle Control Valve (ICV, or 'Stepper') I believe.
    The other one is the Hose that comes down from the Oil Condenser/Separator Box up at the Headstock, which is 'fed' by the two Hoses from the Cylinder Heads.
    Not sure which is which, but I'm guessing the one that loops over and straight down goes to the ICV.
    There will be heavy Oil Vapour in the Cylinder Head Hoses, that's why the Condenser/Separator Box is there, and why when they crack/split, they make a real mess.

    Any Oil that condenses in the Box flows down the Hose that goes into the Sump, next to the Drain Plug.
    Vapour gets sucked into the Airbox via the other Hose.

    Did you have Oil in the Idle Control Valve Hose, or just the other one?

    Blowby.jpg
    Hoses 5 & 6 are the ones from the Cylinder Heads.
    8 is the Oil return line to the Sump from the Box.
    12 is the Vapour line from the Box to the Airbox.
     
  13. scottmastrocinque

    scottmastrocinque Scott Mastrocinque GT Famiglia

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    :)

    Thanks John except I understood all of this. My problem was solved a long time ago. I’m the original poster providing my findings and solution.

    I think you should be directing your reply to saffermoto who seems to have recently developed the problem.

    Thanks again!
     

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