I have a Lionel 6-28036 Southern Pacific 2-8-0 loco that the smoke unit has burnt out. The one below is from the Lionel parts page. This is the second unit in it and am thinking the resistor doesn't have any longevity. I haven't really looked into the unit yet but the question is has anyone here reworked these for better performance and if so have recommendations for parts to use?
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No rework on mine, they work fine as puffers. Need to keep them wet. Your unit is TMCC based, can you turn smoke on and off via CAB-1? If not you may have a triac short, and that is causing you to burn them up. G
The resistors can be replaced. There's no need to replace the entire unit, unless you just prefer not to mess with the necessary soldering.
Repeated resistor burnout is most often caused by allowing the unit to run dry, or just not having enough smoke fluid in the unit. If the unit runs dry once, it can burn the wadding so that smoke fluid doesn't get to the element, which may not cause an immediate burnout but the lack of smoke fluid will eventually cause the element to overheat. The wick should be inspected periodically for blackening at the resistor and replaced if it is hardened. If there is black crud on the resistor, that should also be removed with a brush or some kind of pick. The fluid acts as a coolant, in addition to making the smoke when it vaporizes. A smoke unit should be refilled as soon as the smoke production looks thin. The puffers tend to need fluid about every ten or fifteen minutes. I've got a whole bunch of engines with puffer units (including a couple of those Lionel 2-8-0's), I almost always have them smoking when I run them, and I've replaced one resistor in the last ten years. And that was on a smoke unit that had shorted out.
If you remove the sleeve from the resistor and pack the unit with a fluffed up long wick, you will get good smoke.(wick part attached. contact boxcar bill for parts)
Do what GGG says. It does sound like an electrical issue. Do you leave it parked on a powered track while running other trains with smoke unit on?
Thanks for all the replies!
I checked the R2LC in another loco and the smoke function works good there. It hasn't sat on a powered siding. I'll spend some time fiddling with it this weekend. I'll check for a blackened wick.
I typically keep what I think is a good amount of fluid in there but the reminder to keep it wet is good.
If you want better smoke after you sort it out, I replace the stock 27 ohm resistor with a 20 or 22 ohm 3W wirewound resistor. It'll make a significant difference.
In regards to better smoke...what about what I used to do when I was a kid (and still do with puffers sometimes, old habits are hard to kick!!!).......just leave it in neutral with the juice cranked up for a while then let'er rip. Probably not so good for the smoke unit but.....
If you want better smoke after you sort it out, I replace the stock 27 ohm resistor with a 20 or 22 ohm 3W wirewound resistor. It'll make a significant difference.
I would not do this with a puffer. Going to 20 or 22 with a fan driven smoke unit is fine, but if you idle in neutral it will get extremely hot.
Smoke is all relative, but my 28000 series TMCC puffers all make great PW like smoke (blow smoke rings) as is. I don't even cut off the sleeve. G
The cure is not to sit in neutral with the smoke on. I have this dandy little circuit that I've used on a couple of locomotives that senses when the motor has power and closes a relay. Sounds like a perfect application, have it cut off the smoke when you're not moving. 
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