While working on the C&O/Chessie in 1980 I was called to protect the job of head brakeman on a mine run our power was 3 U23Bs and we had about 70-80 cars and would return with around 112-115 loaded hoppers...We left Russell around 10-11pm and had a uneventful trip to the mine.I had not worked with this conductor or engineer before a real oddity in its self..The first thing I noticed the old engineer said a little prayer before starting out something I never seen a engineer do before but I said nothing about it even though I thought it was a good idea.We finish work at the mine and was making the return trip when our engineer starting singing hymns(he had a great voice) I have long forgot the hymn he was singing but I notice he stopped in mid word and said "Son That didn't sound right!" I replied I did not notice but it sound good and please keep singing. At that the old engineer turn and smiled and said Son,I was not talking about my singing but that odd noise from this unit.Again I replied I did not hear anything unusual.He turn and looked back over the units and just shook his head.So he begin singing hymns again this time there was a loud thump bang thump from the engine compartment but no alarms in the cab.So we stopped the train and the engineer and I started looking over the unit for anything unusual and found nothing amiss.The conductor radioed and asked what happen? And I told him why we stopped..Well we continue on our way and all was going fine and dandy.Of course when we got to BS(Big Sandy) Jct we had to wait on several trains on the Kanowa Sub like usual..We finally got the signal and the engineer open the throttles on those GEs.THUMP! BANG! THUMP! WRUMF!! The sky turn reddish orange and the old engineer and I bailed after he shut off the throttle and set the brakes in emergency.After running a very short distance we stopped and looked back expecting to see a fire but the units seem to be just fine thank you.A guy(the tower operator?) came running up and asked if we was ok..We replied yes,we are fine..By this time a Cattletsburg Police Officer drove up with lights flashing and ask what happen as he saw a huge fireball light up the sky and thought there was a derailment and explosion he was plainly shaken up by what he saw..By this time two other things happen.1 we could hear fire trucks coming and 2 the conductor arrived in a car that he had flagged down and got a ride in.The conductor also shaken up as he said they saw this huge fire ball from the caboose and tried to contact us on the radio(in my haste I forgot the radio) and thought we was hurt or worst(or words to that affect).Well after checking the units and with the fire department looking on we whistle off.Upon arrival at the Russell engine terminal the engineer wrote a report on the way that unit was acting..From that day today I never did hear what the problem was but was told by several engineers GEs would do that from time to time but they never heard of a fireball that big!