Section 2 - Cylinder Head - Group 02 Cylinder Head Valves - Magnetic Crack Inspection (2-10) M11 Page 2-33 Cylinder Head Valves - Magnetic Crack Inspection (2-10) Use the magnetic particle residual method to inspect the valves for cracks. The exhaust valves contain two types of metal, and must be inspected by the coil shot method. There will be a magnetic leakage apparent at the point where the two metals are welded together. The leakage will appear as a wide pattern of magnetic particles. Magnetize the valves in a coil of 100 to 200 amperes. Inspect the valves with residual magnaglo. A broad fuzzy pattern will appear at the welded joint on the exhaust valves.
If there is a distinct line in the pattern, the valve must be replaced. The intake valves contain only one type of metal, and must be magnetized and inspected in two directions. Use the magnetic coil method and inspect with residual magnaglo the same as exhaust valves. Magnetize the intake valves again with a headshot at 500 to 700 amperes. Inspect the valves again with residual magnaglo. Acceptance Criteria (Exhaust and Intake Valves) NOTE: ‘‘Visible’’ means an indication of a crack can be seen through a three power magnifying glass after the magnetic particle suspension is removed. Area (1), no indication longer than 12.70mm [0.500 inch]. NOTE:
There must be no more than five indications or no indications closer together than 3.18mm [0.125 inch]. Areas (2, 3, 4 and 5) must not have any magnetic indi- cations or visible indications. Remove all magnetism and clean the acceptable valves.