Burning up smoke units

What is the part number of the smoke element you are using?
I would use an 8141-55 element in an MPC era steam engine. This smoke element is designed for use at track voltage. Don't forget the fiberglass sleeve around it.
The few newer smoke units that I have repaired take their power through some electronic circuitry, and use much lower voltage.

I'm pretty sure they're not supposed to visibly glow like that.

You're probably missing a resistor or something. When you removed the original smoke unit was there some other electronic doodad soldered to it that you looked at and said, "Awww, we don't need that?"

As I posted above, MPC era smoke units operate at track voltage.
They do not have any sort of device to drop the voltage.
They should not glow. The heater element normally has a fiberglass sleeve over it.

CW is correct. This has the same PW style smoke unit, just a liquid element, not pill. No diodes or anything else. Each of these did come with the element in a sleeve, and a thin bit of what looks like insulation. This last time I added a bit of Rock Wool insulation to see if that helped maybe absorb the fluid. The red hot glow happened each time within ten minutes of running, and then the smoke stopped. I bought four elements from the same parts guy at the local Dupage show, so I don't know what part number I was given. I guess I'll try a different parts source and see what happens. It's got to be just the element itself, right? There's no trick or added part I'm missing?

If you're using the stock 27 ohm 3W resistor, I can't imagine how you're getting it to glow on track voltage!  Exactly what are you putting in there to replace the resistor?