TM 5-2420-230-24-2
A/C Cylinder Head (QE Models) (012-104)
B3.9 and B5.9 Series Engines
Page 12-40
Section 12 - Compressed Air System - Group 12
Clean (012-104-006)
WARNING
When using solvents, acids, or alkaline materials for
cleaning, follow the manufacturer's recommendations
for use. Wear goggles and protective clothing.
Soak the parts in a kerosene emulsion-based cleaner de-
signed to remove carbon. The cleaner must have a pH of
9.5 or less to avoid turning aluminum parts black. The
cleaner manufacturer or supplier can be contacted about
solution concentration, temperature, and soak time.
NOTE: Do not use a scraper to remove carbon and scale;
the sealing surfaces can be damaged.
The parts can be scrubbed with a stiff, nonmetallic bristle
brush.
Inspect for Reuse (012-104-007)
Inspect the intake and exhaust valves for cracks or damage.
Measure the flatness of the intake and exhaust valves. Both
valves must be flat within 0.03 mm [0.001 in].
Replace valves if cracked, damaged, or not flat.
NOTE: Holset Engineering Co., Inc., recommends new
valves be installed.
L-1244