ENGINE OVERHAUL PROCEDURES - GENERAL INFORMATION
PENETRANT INSPECTION
Zyglo
The Zyglo process coats the material with a fluorescent dye
penetrant. The part is often warmed to expand cracks that will be
penetrated by the dye. When the coated part is subjected to inspection
with a blacklight, a crack will glow brightly. Developing solution
is often used to enhance results. Parts made of any material, such as
aluminum cylinder heads or plastics, may be tested using this process.
Dye Check
Penetrating dye is sprayed on the previously cleaned
component. Dye is left on component for 5-45 minutes, depending upon
material density. Component is then wiped clean and sprayed with a
developing solution. Surface cracks will show up as a bright line.
ULTRASONIC INSPECTION
If an expensive part is suspected of internal cracking,
Ultrasonic testing is used. Sound waves are used for component
inspection.
X-RAY INSPECTION
This form of inspection is used on highly stressed
components. X-ray inspection maybe used to detect internal and
external flaws in any material.
PRESSURE TESTING
Cylinder heads can be tested for cracks using a pressure
tester. Pressure testing is performed by plugging all but one of the
holes in the head and injecting air or water into the open passage.
Leaks are indicated by the appearance of wet or damp areas when using
water. When air is used, it is necessary to spray the head surface
with a soap solution. Bubbles will indicate a leak. Cylinder head may
also be submerged in water heated to specified temperature to check
for cracks created during heat expansion.
CLEANING PROCEDURES