What was found
DURING COMPLIANCE OF SB 388C, 3 EXHAUST VALVE GUIDES FAILED TO HAVE SERVICEABLE MEASUREMENTS. NR 4 CYL EXHAUST VALVE STUCK FULLY CLOSED. VALVE MOVEABLE WITH MINIMAL PRESSURE, NO DAMAGE TO OTHER COMPONENTS. NR 6 CYL EXHAUST VALVE GUIDE CLEARANCE MEASURED .0315 INCH (ACCEPTABLE RANGE IS .015 INCH TO .030 INCH). CYL WAS REMOVED, REPAIRED AS NECESSARY, AND THEN REINSTALLED. THIS ENGINE HAS HAD SB 388C PERFORMED ON IT AT THE FOLLOWING TOTAL HOURS, 202.5, 602.7, 802.2, 948.9, 1057.4, 1078.0, 1092.6, 1245.6, 1451.1, 1650.1, AND 1799.9. NR 3 AND NR 4 CYL EXHAUST VALVE GUIDES HAD FAILED TO MEET MINIMUM TOLERANCE AND HAD BEEN REAMED AT LEAST ONCE PREVIOUSLY.