6-18271 CPR Engine , Smoke Unit failure, fried components?

Pull the wheel sets off, inspect the gear connected to the motor,  suspect drag from no grease in the gear area . Amps would go up and overheating the motor would occur.  Never trust the MFG puts good quality grease in the gear area. New or old thats the # 1 item  I check. I use Mobil 1 grease. pack the gear in it and check the gear for damage to the gear.

This is obviously not the motor since turning the smoke unit off solves the problem.

What has likely happened is the smoke triac has shorted on the R2LC and it's providing the smoke unit with full track voltage instead of half-wave track voltage.  That being the case, instead of around 6 watts in the smoke unit, it's getting twice that much power and overheating.  Spectacular smoke, but it cooks the smoke unit in the process if it goes on too long.

The fix will involve getting the smoke triac on the R2LC replaced (if it's damaged the PCB, you may need a new R2LC).  Next, you'll need a smoke unit build at a minimum, and likely a replacement PCB, see below.  At a minimum, I'd replace the smoke unit resistor and the wick material in the smoke unit.

Thank-you for the advice.  Any idea what would have caused this to occur in the first place?

Hard to say, sometimes they just fail.  Without looking for clues in the locomotive, I really can't say why it would fail.  My first step would be to do stuff like check the smoke unit condition, and closely examine the wiring between the smoke unit and the TMCC motherboard.  If you get a random short to ground (pinched wire, etc.), that can take out the triac, and they frequently fail shorted.  Once I know the smoke unit and wiring are OK, I test the R2LC and replace the triac if possible.  I'm guessing before the smoke unit is "OK", you are likely going to have to do a little repair there.

Is there any chance that holding down aux 9 too long for increased smoke output could damage the triac.

This is assuming you run TMCC or Legacy.

You bet, excessive use of the boost increases the power dissipation of the triac.

Got it.  I guess it must of just failed.  I am using TMCC with an old ZW.   I've not used Aux 9.    I tested the track voltage and it maxes out at 17V.  I assume all is ok in this area. 

I don't have the tech acumen that gunrunnerjohn has, but I likely can remove and replace the R2LC and the Fan Unit PCB along with putting new smoke unit resistor and the wick material in the smoke unit.  Should I order the parts from Lionel directly?  Better option?

Well, I'd swap the R2LC with a working one to see for sure if that's the issue.  If the smoke unit PCB isn't really burned, you can probably re-use it, just replace the resistor.  In any case, new wick will be called for.

Send me an email, I have all the parts for the smoke unit and new R2LC boards.  If possible we can replace the triac on your R2LC for less than buying a new one from Lionel.  If not, then we can replace it.