Crack detection & repair

Causes of cracks in heads & blocks• Overheating

• Freezing• Expansion and contraction• Cracks start from water jacket side

Only heads and blocks are repaired

Copyright 2003 Gary Lewis – Dave Capitolo

Crack detection & repair

Design & production problems• Core shifts

• Sharp corners after machining• Siamese valves & ports

Crack detection & repair

Dry magnetic particle inspection for iron parts• Clean area to base metal

• Set up magnetic field on part• Dust with magnetic powder • Cracks will be visible• Test in different directions

Crack detection & repair

Wet magnetic particle inspection• For connecting rods & crankshafts• Clean parts to base metal• Part is magnetized under black light• Spray with solvent carrying magnetic particles• Cracks become visible

• Part can then be demagnetized

Crack detection & repair

Dye penetrants• Used on all materials• Clean parts to base metal• Coat part in penetrant• Wait a few minutes and wipe off excess• Spray part with developer & allow to dry to a powder

Crack detection & repair

Pressure testing castings• Used for heads & blocks on all materials• Water passages are blocked with plates• Pressurize passages to 3 times cooling system pressure• Spray part with soapy water or submerge part

Crack detection & repair

Crack repair pins• Full length must be accessible with drill & tap• Locate the crack• Drill 1/8” hole past each end of the crack• Drill & tap holes• Use tapered reamer to make tapping easier

Crack detection & repair

Sleeving cracked cylinders

• 1/8” and 3/32” wall sleeves• .002” average interference• Press or shrink

Crack detection & repair

Sleeving other holes

• Head bolt holes• Oil passages

Crack detection & repair

Stop drilling

• Drill 1/8” hole past crack• Not done near water, oil, or combustion chamber

Crack detection & repair

Welding Aluminum

• TIG• Prepare crack by gouging

• Preheat casting• Gas acts as a shield

Crack detection & repair

Welding Iron, method #1

• Oxy-acetylene torch• Preheat part to 1300ºF

• Iron filler rod

Crack detection & repair

Welding Iron, method #2

• Flame spray welding• Gouge area

• Preheat casting to 650ºF

• Heat area red hot & introduce powder

Crack detection & repair

Sealing

• Sodium silicate• Heated & circulated for an hour

• Pressurized to 55 psi

• Cures in air in 24 hours

• Used to repair porosity problems• Can be added to cooling system

Crack detection & repair

Vacuum impregnation

• Vacuum applied to resin filled tank • Pressure applied

• Rinsed in water