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Removing seized cylinder

Discussion in 'Technical and Troubleshooting Torque' started by mrvargo, Mar 13, 2007.

  1. I have a '94 R100 BMW with a seized left piston. I have removed the head and now can't get the barrel off, she is stuck tight. Does anyone know of any technique or tools that I might try?

  2. I would keep filling the cylinder with wd40 and give it a few taps every day with a plastic or rubber mallet. Ive seen a few engines unlocked this way.
  3. Here's a solution if the WD40 approach doesn't work...

    Take a sparkplug (with a thread that fits your bike), and saw off porcelain section above the "nut"

    Use a punch to knock out the rest of the electrode. Now you have a hollow metal tube with a thread and a nut.

    Weld a pipe fitting with the same thread as a grease gun nozzle onto the tube you made in the previous step.

    This one...
    was made to do a similar job (unsticking a brake cylinder). Don't use a nipple - for a piston you'll need a threaded fitting.

    Remove the pushrods so the valves stay closed, and bolt the head back on

    Screw you sparkplug fitting into the plughole, screw on the greasegun and start pumping. You can get a few 1000psi this way - that should be plenty to get the cylinder moving.

    Once the piston is free, check that it hasn't left aluminium smears on the cylinder wall. If it has, muriatic acid will get them off without damaging the cylinder.
  4. ^^^^^^Wow thats brilliant :grin:
  5. That is pretty darned clever. Luckily the WD40 and some gentle persuasion with a rubber handled claw hammer is all it took. All good now, thanks for your help chaps.