How to check for cracks in an engine block

Written by m.l. browne
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How to check for cracks in an engine block
There are multiple methods for checking engine block cracks. (engine image by goce risteski from Fotolia.com)

Cracks in any engine are serious, and can lead to catastrophic failure if not discovered early and remedied. Cracks allow fluid and lubricant leakage into or out of engine parts they should not contaminate. What begins as a hairline fracture can over time and miles increase to the point where the engine no longer works at all and cannot be repaired.

While any part of an engine might fail due to overheating, metal stress, excessive temperature variation or load fatigue, you can usually find any cracks by inspecting the engine block, moving shafts, connecting rods, valve seats and cylinder heads. The most effective methods for crack detection include visual inspection, magnetic particle inspection, penetrating dyes and pressure testing.

Skill level:
Easy

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Things you need

  • Two magnets
  • Three ounces fine iron oxide particles
  • Shop light
  • Small paint brush
  • UV light
  • Container of fluorescent penetrating dye
  • Air pressurizer
  • Large water tank

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Instructions

  1. 1

    Allow the engine to cool completely.

  2. 2

    Inspect the block for cracks. If it is not easily accessible, remove it so that you can get a clear look at. If the block is encased, you may need to disassemble it to visually confirm there are no cracks.

    How to check for cracks in an engine block
    Look closely at the engine block to identify cracking. (Classic Car Engine Refurbished image by Janet Wall from Fotolia.com)
  3. 3

    Reassemble and replace the part in the engine if you do not see cracking. Otherwise, replace the block before you reassemble or restart the engine.

  1. 1

    Allow the engine to cool completely.

  2. 2

    Determine the composition of the block you want to inspect. This technique only works for cast iron or steel parts, and will not work on non-ferrous metals (non-magnetic alloys, magnesium, titanium or aluminium).

    How to check for cracks in an engine block
    Magnets create a field for testing the block. (Schwebender Magnet image by Edwar Xie from Fotolia.com)
  3. 3

    Create a magnetic field around the block with electromagnets or permanent magnets and shine a light directly on the part.

  4. 4

    Pour or paint iron oxide particles on the part. If the part has surface cracks, they will cause the iron particles to act as magnetic poles along the length of the crack.

  5. 5

    Replace or repair any block that exhibits cracks.

  1. 1

    Allow the engine to cool completely.

  2. 2

    Spray the fluorescent penetrating dye so that it coats the block.

    How to check for cracks in an engine block
    Penetrating dyes identify engine block cracking. (moment of spray image by Robert Kelly from Fotolia.com)
  3. 3

    Wipe excess dye from the block after a few minutes.

  4. 4

    Turn on the UV light and pass aim it at the dye-coated part. Any dye that penetrates a crack in the block will appear under the light.

  5. 5

    Replace or repair any block that exhibits cracks.

  1. 1

    Allow the engine to cool completely, and remove the engine from the vehicle.

  2. 2

    Ensure that all water conduits are completely plugged.

  3. 3

    Use air to pressurise the engine casting and submerge the casting in water. If air bubbles rise, the block does not hold pressure and needs repair or replacement.

    How to check for cracks in an engine block
    Testing air pressure confirms engine block integrity. (pressure-gauge image by Dusan Radivojevic from Fotolia.com)
  4. 4

    Replace or repair any block that exhibits cracks.

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