748 748 Oil Leak

Discussion in '748 / 916 / 996 / 998' started by Dolton748, May 7, 2014.

  1. Morning all, I have just landed myself a 2001 748 S. Only 10k on the clock and a full ducati service history. It's awesome. However, following my last few rides I have noticed small build up of oil behind the rear cylinder on the top of the crank casing. I think it maybe coming from the rear cylinder base gasket. I can live with it for now just have to clean it after each ride. Anyone else experience the same thing?
     
    #1 Dolton748, May 7, 2014
  2. The more usual cause of oil build up around there is a leak from the breather valve. It can be unscrewed and sealed with threebond or RTV of somesorts. It's fiddly as access is tight, but not rocket science. Check also the short pipe running from it as they can split.
     
    #2 nelly, May 7, 2014
  3. There is an oilway in the crankcase which is not used . It is sealed with an o ring wich is squashed down by the base of the cylinder. A lot of people cure it by blanking the hole in the cases
     
    #3 higgy748, May 7, 2014
  4. :upyeah:My bank account would be a lot happier if it is! thanks I will look into it.
     
    #4 Dolton748, May 7, 2014
    Last edited: May 7, 2014
  5. Sounds to me like it could be the breather, worth looking at in more detail first
     
    #5 Phill748, May 7, 2014
  6. I had exactly this - grub screw in there sealed cured it
     
    #6 Loverobot, May 7, 2014
  7. Cleaned entire area down and watched ticking over for 15 minutes small accumulation of oil built up in small area on the base gasket. (Breather side) Not much, but enough to leave a small pool after a 2-3hr ride.
     
    #7 Dolton748, May 10, 2014
  8. In conclusion, I am 99% sure the oil is coming from rear cylinder base gasket. What a ball ache!!!
     
    #8 Dolton748, May 10, 2014
  9. Mine developed a leak from the oil way after I changed the head gaskets for the newer type (thinner head gasket/thicker base gasket), as I used the old type 'O' ring (too thin) so it leaked as soon as I started it up.

    At that point had to strip it down again, so I tapped a thread into the oilway (can't remember if 4 or 5mm?), then Loctited a grubscrew into the hole so that it can't leak again even if there's no 'O' ring in it - pain in the arse of a job if you don't need the cylinder off for anything else.

    Maybe, if you tighten up the head bolts a little it might 'cure' it? got to be worth a try before removing the cylinder?


    P1010271b.jpg
     
    #9 Dukedesmo, May 11, 2014
  10. Do you know what the torque requirement is for the head bolts?
     
    #10 Dolton748, May 12, 2014
  11. First torque 14.7 NM
    and
    Then 29.4 NM
    and
    Final Torque 52 NM +\- 0.10 according to my Ducati manual
     
    #11 Red998, May 12, 2014
  12. Will I need a special tool for this? I have seen a few threads else where about a "c" shaped adaptor for the torque wrench that is required. If so, does anyone have a link to where I can get one from?
     
    #12 Dolton748, May 12, 2014
  13. Theres a flat adapter thingy on ebay £15 IIRC.
     
    #13 Nelson, May 12, 2014
  14. I searched flat adaptor thingy but to my surprise didn't come up with anything.
     
    #14 Dolton748, May 12, 2014
  15. #15 Dukedesmo, May 12, 2014
  16. :Bag:
     
    #16 Nelson, May 12, 2014
  17. There are two head nut sizes, one is 14mm and the other 15mm.
     
    #17 Red998, May 12, 2014
  18. :(All head bolts are torqued correctly. I can live with it for now providing it does get any worse.
    Thanks all for the helpful info.
     
    #18 Dolton748, May 17, 2014
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