An unusual way to remove a broken hairpin

An unusual way to remove a broken hairpin

When removing the head from the cylinder block, broken pins occur. This is a common problem that can be solved in many ways. The easiest way is to use an extractor to unscrew broken bolts, but it doesn’t always help. In this case, you have to knock on the breaker, weld a bolt to it and try to unscrew it. This almost always helps, but there is, albeit small, a chance of breaking the block. If it costs several thousand dollars to replace it, then it is extremely unpleasant. To avoid this risk, you can remove the chips chemically. It is long, but safe.
An unusual way to remove a broken hairpin

Materials and tools:


  • set of drills;
  • lemon acid;
  • dry air heating element 1 kW or more;
  • dropper;
  • syringe;
  • thermostat with remote sensor.

Removing the stud breaker


Using a drill, or better yet a drilling machine, you need to drill the center of the breaker with a thin drill to its full depth.
An unusual way to remove a broken hairpin

The hole is then expanded with a larger diameter drill.
An unusual way to remove a broken hairpin

It is advisable to make passes with drills with an increase in their thickness by 1 mm.In this case, there is no risk that one of them will break under the load and remain in the stud, which will create many problems. You need to widen the hole until the breaker is completely drilled out and only its thread remains in the block. It is very important not to snag the block threads with the drill.
After drilling, a steep solution of citric acid is poured into the resulting hole. The liquid will evaporate, so a supply of drops is set through the dropper to maintain the given volume of solution.
An unusual way to remove a broken hairpin

Simultaneously with the supply of acid, it is necessary to ensure heating of the block. To do this, a dry-type heating element is applied closely to it.
An unusual way to remove a broken hairpin

The heating element itself is connected through a thermostat, the sensor of which is lowered into the mounting hole of the adjacent unscrewed stud with oil filled.
An unusual way to remove a broken hairpin

You need to set the temperature to plus 80 degrees Celsius, which is completely harmless for the unit. The opposite side of the heating element should be insulated with some kind of blanket so that it cools down longer.
An unusual way to remove a broken hairpin

You will also need to cover the cylinders with oiled paper to prevent splashes of citric acid from getting into them, as this will create small potholes on their walls. The block is left in this form for 1-2 days. The less metal from the breakage remains in the block, the faster everything will be dissolved. Periodically, you need to select the acid with a syringe, inspect the hole and fill it with a new solution, as the concentration of the old one weakens.
An unusual way to remove a broken hairpin

Having dissolved the chip, you need to refresh the threads with taps. After this, the engine can be assembled. This method takes a long time, but it ensures that the block remains intact. If the chip cannot be removed by other means or the block is too expensive to risk, then this option for solving the problem will be quite acceptable.
An unusual way to remove a broken hairpin

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Comments (9)
  1. YURI
    #1 YURI Guests 8 February 2020 23:18
    4
    It’s better to etch away aluminum with nitric acid, the nitrogen will not touch the aluminum, but it will dissolve the iron
    1. Guest Alexey
      #2 Guest Alexey Guests 9 February 2020 10:09
      1
      I welded an 8mm bolt on a cast iron block (a 10mm break). I immediately poured cold water on it and unscrewed it. The extractor did not help. It broke off inside.
    2. putler
      #3 putler Guests March 9, 2020 01:23
      1
      learn chemistry
  2. Alexander
    #4 Alexander Guests 9 February 2020 10:38
    3
    Yes, and you won’t have to poison. The thread usually just falls out on its own
  3. Sonya
    #5 Sonya Guests 9 February 2020 16:37
    1
    It’s easier to insert, for example, a triangular file with the back end into the drilled hole in the stud (lightly tapping it) and unscrew it with pliers.
  4. Vietnamese sergeant
    #6 Vietnamese sergeant Guests 9 February 2020 23:52
    1
    On an expensive block that is scary, it is unlikely that there will be such studs.
  5. Guest Victor
    #7 Guest Victor Guests 10 February 2020 18:39
    1
    Will the drill take this pin? As you know, the studs are hardened
  6. Guest Evgeniy
    #8 Guest Evgeniy Guests March 9, 2020 03:54
    2
    As a rule, they drill with a left-handed drill; when the stud wall is weakened and the drill heats up due to friction, the stud fragment is easily unscrewed, although there is a possibility of losing the drill...
    1. Guest Anton
      #9 Guest Anton Guests 23 March 2020 15:54
      2
      Well, you know, if you have a left-handed drill, there’s no need to worry about it...