As Fred says it is normal to see a little smoke during the warm up phase as steam oil residue inside the smokebox burns off. However if this is persistent then it might indicate other issues. Cracking open the smokebox door on an Accucraft loco at light up for a couple of minutes is almost a ritual for me.
My Accucraft C-19 recently failed due, as it turned out, to a failed soldered joint on a nut, that seemingly acted a "stopper on one end the superheater tube (the nut writing this was at the other end
). It had the service engineer scratching his head initially when I took the loco to him as he had not seen this type of failure before.There were suggestions if the worst diagnosis came true I might be writing a largeish cheque for a fix. Let me recount how the symptoms manifested themselves before the final failure and need for repair.
I tend to use my locos infrequently so I'm in the habit of going through one or two basics before running. I had noticed my C-19 was not "pulling" quite as well as it had in the past. So I did all the usual things to check the gas supply and R/C operation of the regulator and reverser. I had oiled around and made sure all reservoirs were full and then checked for any obvious binding in the wheels and motions. I had noticed though a little seepage of steam from where I didn't expect it for some time but hadn't given that a second thought as the loco had been running well up till then. I ran the loco again, still not great, so I opened up the smokebox door and noticed that a forked blue, not a billow of yellow signifying unburnt gas, flame was showing proud of the end of the boiler/burner tube. Not normal, the flame should have "popped back" and be fully contained in the fire tube. So I shut down the loco and tried to relight. The superheater tube at this point was glowing red hot (probably what you are looking at down the smoke stack), which I was told subsequently was not abnormal. Tried to relight it and that is where I started to have problems with the burner going out repeatedly as soon as the boiler had raised just a few lbs of pressure and when I opened the regulator. I also noticed that what I thought was oil burn off turned out to be paint inside the smokebox being, shall we say, overheated and when I opened the smoke box door that forked blue flame, projecting out of the fire tube, was back again.
Off the the trusty service engineer, problem fixed for a fee of £60. I can only relate my experiences and see if some of it resonates with others. MaxThis
P.S. I really need an editor