What was found
NR 2 ENGINE AT IDLE, RUNS 40-50 DEGREES C HOTTER THAN NR 1. AT IDLE NR 2 N1 FLUCTUATES +1.3% TO -0.5% FROM A STABLE NR 1 ENGINE N1. VIBRATION ON NR 2 CYCLED FROM 03. SAME AS NR 1 TO 0.8 ON NR 2. ACFT GROUNDED. RAN BOTH ENGINES, COULD NOT DUPLICATE DISCREPANCY. BOTH ENGINE PARAMETERS STABLE WITH NO FLUCTUATION. AS A PRECAUTIONARY MEASURE, REMOVED AND REPLACED THE NR 2 ENGINE BLEED AIR CHECK VALVE IAW AMM 36-11-02-000-801, AND AMM 36-11-02-401-801. OPS AND LEAK TESTED GOOD, RAN BOTH ENGINES AND ENGINE PARAMETERS NORMAL WITH NO FLUCTUATION.