Torn push rod seal; Replace head gasket and o-rings??

Discussion in 'Airheads' started by Blane, Oct 6, 2012.

  1. Blane

    Blane Been here awhile

    Joined:
    Apr 2, 2006
    Oddometer:
    305
    Location:
    East of Slowdessa
    I'm putting together an R100 Frankenbeemer. I just got the heads on and everything torqued up a couple of weeks ago and noticed when I was installing the exhaust today that one of the new push rod seals was torn. :becca

    Now everything on the right side has to come off to replace that stinkin' seal. My question is, even though the bike hasn't been running, am I going to have to replace the head gasket again? Also this is one of those cylinders that requires a large o-ring around the cylinder and the 2 o-rings around the studs. Am I going to have to replace those as well? I just want to make sure I order everything at once and save on shipping.
    #1
  2. bay

    bay Adventurer

    Joined:
    Aug 7, 2010
    Oddometer:
    43
    Location:
    south demark
    hi,you will only have to replace the two small o rings and the larger base o ring ,i would of thought the head gasket is fine.i have had the heads off mine and reused the gasket with no ill effects.
    #2
  3. mykill

    mykill odd

    Joined:
    Feb 6, 2008
    Oddometer:
    1,183
    Location:
    Los Angeles
    Leave the head attached to the barrel with the 12 and 6 o'clock bolts. No need to replace the o-rings, they are still fresh.
    Just slide the barrel out with engine at TDC keeping the rings in place. If you used sealant at the base, you have some cleaning to do and careful but awkward re-application. But no big deal.
    #3
  4. disston

    disston ShadeTreeExpert

    Joined:
    Mar 22, 2011
    Oddometer:
    12,363
    Location:
    Silver Spring, Md
    A lot of riders would take the wrist pins out of the pistons so the pistons will stay in the cylinders and the heads stay on top of the cylinders. It's OK to do that way but be very careful when reinstalling the wrist pin circlips. The circlips have to be prooved or proofed. There's not a lot you can see when performing this operation and everything is still attached to the engine. There is just not a lot of room to stick your head in there.

    Even a circlip installed in a place where you can see what is happening is proofed. Once installed, you think it's in place, the circlip is spun in it's bore. Spin it enough so that you can see it is seated. That's it. Prove all circlips.

    My friend lost a piston, cylinder, cam shaft, oil pump and lifters. Because a circlip was not fully seated.
    #4
  5. Uncle Pollo

    Uncle Pollo Long timer

    Joined:
    Jun 1, 2006
    Oddometer:
    50,690
    Location:
    Albuquerque, Neue Messico
    Take the valve ro kers off and move the whoe thin up a bit. Tdc or u will spend some time with the ri.g compressor. Master te h at bmw did all pushrod seals that way. 30 minutes. Readjust the valves before reinstaling valve covers.
    #5
  6. supershaft

    supershaft because I can

    Joined:
    Sep 9, 2010
    Oddometer:
    9,116
    Location:
    San Francisco Bay area
    Where did you get the seals Blaine?
    #6
  7. Padmei

    Padmei enamoured

    Joined:
    Mar 12, 2008
    Oddometer:
    4,099
    Location:
    Nelson New Zealand
    Have you checked for leaks? I put one in a few weeks ago that got a bit squished & a bit is hanging out. I didn't notice it till after I'd ridden it for a few hundred Kms.
    Replace if you want- it may bug you that it is there smirking at you :D - but it may not leak at all.

    I got mine from motobins.
    #7
  8. Box'a'bits

    Box'a'bits In need of repair

    Joined:
    Sep 26, 2008
    Oddometer:
    3,162
    Location:
    Wellington, New Zealand
    <iframe width="420" height="315" src="http://www.youtube.com/embed/rX7wtNOkuHo" frameborder="0" allowfullscreen></iframe>
    #8
  9. Padmei

    Padmei enamoured

    Joined:
    Mar 12, 2008
    Oddometer:
    4,099
    Location:
    Nelson New Zealand
    barstard :thwak
    #9
  10. Blane

    Blane Been here awhile

    Joined:
    Apr 2, 2006
    Oddometer:
    305
    Location:
    East of Slowdessa
    From Hans at Hucky's BMW Parts.
    #10
  11. Wirespokes

    Wirespokes Beemerholics Anonymous

    Joined:
    Jul 26, 2002
    Oddometer:
    8,719
    Location:
    Jackson's Bottom Oregon
    I wouldn't replace the ORings. As said, they're still fresh.

    I've re-used used head gaskets in my bikes many times, only freshening the sealant around the top studs and pushrod tubes. Hasn't been a problem yet. And in your case, it's still new with no heat cycles - but best to leave the head and cylinder together.
    #11
  12. supershaft

    supershaft because I can

    Joined:
    Sep 9, 2010
    Oddometer:
    9,116
    Location:
    San Francisco Bay area
    I wonder if they are BMW. There are some bad ones floating around from Motobins or Capital Cycle or some place like that.

    Or maybe it was from BMW (the bad ones). They are selling crap as if they were Capital cycle lately. I just got a new cadnium plated front axle. WTF? It's going to turn to rust in no time.
    #12
  13. Prutser

    Prutser Long timer

    Joined:
    Aug 5, 2012
    Oddometer:
    1,336
    Location:
    The Dutch swamp
    Did you put any sealant on the push rod tubes before the seals where put on them ?

    Have seen a lot of those seals slide over the ring on the tube and than burst because some sealant was used there.

    Just thinking why they would burst.
    Of course there could be some bad ones out there.
    #13
  14. Blane

    Blane Been here awhile

    Joined:
    Apr 2, 2006
    Oddometer:
    305
    Location:
    East of Slowdessa
    The tear looks pretty deep from where I could see. You might be right about holding a seal but it won't take long to replace them.
    #14
  15. Blane

    Blane Been here awhile

    Joined:
    Apr 2, 2006
    Oddometer:
    305
    Location:
    East of Slowdessa
    No sealant. Just regular motor oil inside and out as Oak recommends.
    #15
  16. Prutser

    Prutser Long timer

    Joined:
    Aug 5, 2012
    Oddometer:
    1,336
    Location:
    The Dutch swamp
    I replaced a few handsfull of those things but never used oil. And never had a leaking one after mounting them.
    Imo the oil might be the reason they slide over the tubes to far and than start to burst.
    #16
  17. supershaft

    supershaft because I can

    Joined:
    Sep 9, 2010
    Oddometer:
    9,116
    Location:
    San Francisco Bay area
    +1 I think you are better off installing them dry with the mold release rubbed off inside and out and I have installed a bunch of them.
    #17
  18. Wirespokes

    Wirespokes Beemerholics Anonymous

    Joined:
    Jul 26, 2002
    Oddometer:
    8,719
    Location:
    Jackson's Bottom Oregon
    I've always used silicone grease with never a problem. Maybe I shouldn't bother and install them dry.
    #18
  19. Kokopelli

    Kokopelli Yeah, right!

    Joined:
    May 2, 2003
    Oddometer:
    4,856
    Location:
    Rapaura
    I've just asked the same question, hadn't seen this. However, I pinched an o-ring and had the bike running. Since I've also pulled the head, can I reuse the gasket. The blue sealant around the pushrod tube holes and the upper studs has been slightly pulled off. Can I just smear a bit of sealant on there? Is it enough just to replace the damaged 0-ring, or will I need to replace the large o-ring as well. Sorry to ask the same questions again, but my bike has been running for a minute or two.

    I just had to check what the problem was and didn't want to leave the head attached by two bolts over night. Are these o-rings special, or can I just get a generic one, of the same size?
    #19
  20. Stan_R80/7

    Stan_R80/7 Beastly Gnarly

    Joined:
    May 12, 2012
    Oddometer:
    2,409
    Location:
    VA
    FWIW, I replace the pushrod tube seals on my /7 two days ago. All I did was remove the exhaust and carburetors then set the cylinder to TDC and torque (per Oaks recommendation) the cylinder bolts incrementally until they were loose. The rocker assembly and pushrods were removed and oriented for replacement in the same locations. The cylinder was slid out, seals replace, base recoated with Hylomar, o-rings inspected, and then slid back. The valve train reinstalled in the correct location, adjusted for rocker arm end float, retorqued (incrementally), exhaust and carburetors replaced.

    Mine had no gasket or cylinder base o-ring to replace and the pushrod seal o-rings looked OK. I used lighter fluid (Ronsonol) to lubricate the new seals. The most difficult part was cleaning around the cylinder to remove old Hylomar, clean, and recoat. Getting Hylomar was not that easy. The valves were adjusted last before a test ride. Good luck!
    #20