CB/CL 350 stuck oil drain screw

Discussion in 'Old's Cool' started by rudolf35, Dec 23, 2012.

  1. rudolf35

    rudolf35 Warped & Twisted Mind

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    Since my R50/5 project is in the test phase, running up miles, I thought it was time to pay some attention to my CL350. The bike is down tithe frame and I have started to take the motor down. All is going well save the oil drain screw/cap in the bottom of the case.

    I tried a 1/2 inch ratchet, 1/2 in with a two foot cheater bar and a 1/2 inch with a cheater bar plus heat: the bloody thing will not move. Any suggestions?
    :kboom
    #1
  2. MChappy

    MChappy Adventurer

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    Heat the plug then cool it with a wet rag several times. Probably a case of dissimilar metal corrosion

    Sent from my DROIDX using Tapatalk 2
    #2
  3. rudolf35

    rudolf35 Warped & Twisted Mind

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    Good idea; tried it and the cap would not budge - four cycles hot/cold.

    Also tried just a good tap when hot to break the bond, no joy.

    :kboom
    #3
  4. concours

    concours WFO for 41 years

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    more info... You say drain screw/cap.. is it an aluminum cap with a large OD? Or a simple steel drain plug?
    #4
  5. copper.mason

    copper.mason Adventurer

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    try to remove as much oil as possible for safety reasons and than weld a big nut on to it. Worked on my xl250 when it was stuck
    #5
  6. rudolf35

    rudolf35 Warped & Twisted Mind

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    It is a 2" disk with a 19mm faced tip, steel. It is a known issue with older Honda motors. The 19mm faces are in good shape so a slipping wrench is not a issue. As you mentioned earlier, dissimilar metal corrosion.

    I might have to go with a old "fix", take the case down and clamp the 19mm in a vice and try to spin the lower case. Will be a mess but I do not want to blow the threads in the pan.
    :kboom
    #6
  7. rufusswan

    rufusswan Been here awhile

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    Or you could just tap it for a smaller drain plug.
    #7
  8. concours

    concours WFO for 41 years

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    While a helper holds as much torque on it as you dare, (with a nice 6 point socket of course) take a sharp center punch held at a 60 degree angle out near the perimeter and whack it sharply with a 24oz hammer. Works every time. The small divot will be easily filed/blended smooth. I do it regularly.
    #8
  9. bmwhacker

    bmwhacker Still on 3 wheels

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    If the drain plug is steel, heat the aluminum engine areas around the plug with a heat gun and try to remove it while things are nice and toasty. The aluminum expands faster than the steel and might (?) give up it's grasp on the steel plug. That's worked for me a few times.:clap
    #9
  10. rudolf35

    rudolf35 Warped & Twisted Mind

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    That is what I have in mind; that is after I have the case split. I drained the oil out via the left and right side, also the open top - messy but it drained the oil. Once I have the case split I will try heating the alloy locally, with the plug clamped in a vice, the try to twist it loose. If that fails, I will just drill out the center of the plug until I can crush it on itself; will replace it anyway.

    :ear
    #10
  11. ArtCuisin

    ArtCuisin Adventurer

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    I had the same problem when I was 16 (about 36 years ago)
    on my 1972 CL350.
    Laid it on its side, cold, hit with hammer sqare-on.
    Worked for me.
    But that was a long time ago.


    Maybe that experience is why I've pretty much drilled
    and safety-wired drain plugs on everything I've owned
    for the last 25 years. (I don't feel the need to tighten so hard.)

    (Aside: I think it is funny how thinking about buying one of
    those these many years later makes me shudder.)
    #11
  12. Harry94025

    Harry94025 Been here awhile

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    I've owned a couple of CB350's. I always would hit the drain plug on the top (bottom when the bike it upright) of the hex with a good sized hammer before attempting to loosen the drain plug. Then, a 1/2" breaker bar would do the trick...

    Harry
    #12
  13. electroken

    electroken Been here awhile

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    I have one of those drain plugs sitting here in front of me, and I don't see that crush thing happening. My money is on a LARGE air impact wrench and a good 6-point socket.
    #13
  14. MODNROD

    MODNROD Decisions, decisions

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    Wlak past it every morning and night for a week, and hit it with Loctite "Freeze and Release" for a few seconds each time.
    Then just before you walk away, kick it.

    The last bit especially, is important.
    #14
  15. rudolf35

    rudolf35 Warped & Twisted Mind

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    OK, tried heating the lower case (400F in oven) and freezing plug - no joy.
    Tried freezing plug - no joy
    All the while using a impact to jarr the plug lose, this thing has become a part of the case. Any other ideas? Matter of fact, the cylinder studs and inner oil splash shield fasteners are just as frozen.

    I need some sage advice!

    :kboom
    #15
  16. buls4evr

    buls4evr No Marks....

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    Still at this??? A hammer and a sharp chisel works every time. Just replace the bolt. Ugly solution but 100% effective.
    #16
  17. rudolf35

    rudolf35 Warped & Twisted Mind

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    The bolt is a writeoff, just wanted a more elegent way of removing the frozen plug.
    :becca
    #17
  18. Stan_R80/7

    Stan_R80/7 Beastly Gnarly

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    The first thing I would try is putting some kroil on the plug and give that a couple or three of days to work. Internet lore describes ATF mixed with acetone is better, but I haven't gone through that experiment. The next thing I would try is drilling out the plug to get the oil from the crankcase. Once the oil is drained, heat can be applied to the aluminum and the plug cooled. All the while keeping kroil applied to help penetrate the threads. The last thing would be to heat the plug and case together - being careful to not heat melt the case. Then let them cool and repeat that cycle a few times. If none of that worked, an impact wrench on plug would be used. Good luck!


    Edit: I see in the saga that the oil is out of the crankcase. Drilling a hole in the plug will still help after applying penetrating oil. Also, heating the case with a torch to ~300 deg F and with a cold wrench from the freezer, see if the plug can be removed with the wrench and a few blows from a hammer.
    #18