B737 Next Generation Undifferentiated
Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Air Transport Pilot (ATP)
Troubleshooting; Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Returned To Gate; General Maintenance Action
Aircraft
While taxiing out for takeoff; aircraft behind us reported to ZZZ ground control that our right engine was on fire. ZZZ ground control informed us; rolled ZZZ Aircraft Rescue Firefighting (ARFF); and had us turn east onto taxiway 1 and park. All engine indications were normal throughout the event. We turned off of '1' taxiway onto '2' taxiway; set the brake; requested assistance; and secured the right engine. ZZZ ARFF looked over the aircraft and reported that everything looked normal. We taxied to gate XX with ARFF escort.Maintenance informed us that there was an oil seal issue with the right engine. The fire occurred when the oil that was pooling in the tailpipe ignited.  They said it was called 'candle wicking' and it was a term referenced in their manuals.
While taxiing for takeoff; Captain reported that another aircraft crew observed an engine fire on their aircraft. The crew of the taxiing aircraft shut down the engine; and after inspection; taxied back to the gate.