EMPLOYEE & CO-WORKER WERE CHANGING A TRACK ON 151-D-11. THEY HAD 3 BOLTS LOOSE & THE 4TH BOLT WOULD NOT BREAK LOOSE. EE WAS USING A TORCH TO HEAT THE TRACK LINK & A TRACK PIN FILLER PLUG BLEW OUT OF THE PIN, BLOWING HOT OIL ON THE RIGHT SIDE OF HIS FACE.