Melting Smoke Unit Lionel SD-40T...

I have been pulling locomotives out of storage that have not been run in years.  I have had a couple of issues now related to electronics.  Most recently, I took out my Lionel U.P. SD-40 Tunnel Motor (from around 2002-2004?), lubed it and ran it under TMCC.  At first the smoke unit did not seem to work, then it started working, then-very suddenly-it started working too well.  Clouds of smoke came pouring out of it (accompanied by a interesting electrical smell).  Before I could get it shut off, the heat had melted the small rectangular grill (smoke outlet) on the top of the locomotive.  The locomotive was running at between 16 and 17 volts when this happened.  

None of this seemed to interfere with its running or sound capabilities.

Has anyone else run into this?

Is it possible to purchase the smoke outlet grill?

I am not upset with Lionel, by the way, at the engine is between 14 and 16 years old.




RAK TCA 94-3880 TTOS C45 Southern California DCS Demonstration Team Angels Gate High Railers LCCA
Original Post

I think that one is molded in place vs a separate part isn't it?

I'd fabricate one or look for a junk shell to cut up .. or both. Do a homemade that might be removed later and cross your fingers for a cheap shell.

  I don't think it would be too hard a part to make from a chunk of plastic and some brass tube. (I think that has round ports...???)

  An aftermarket part, or brass one from another company might be a possibility too. That would again depend on if it is cast to the shell, or if there are variations to the stack that may have inspired an after market part.

  In the end it's kind of ironic seeing the tunnel motors were built for improved cooling, eh? 

Making a casting off another is also possible, but I think making one would be just as easy once you make a mold, recast it and cleaned it up.


"Still trying to not shoot my eye out"


"Nursing insomnia one railcar at a time"

My aroma therapy? Smoke Pellets.


It sounds like the smoke unit/AC regulator failed.

This is a somewhat common problem. I have experienced it in a steamer from the same era.

The regulator is replaceable. I'd check Lionels replacement parts site to see if the grill is sold seperately.

" No matter how far we travel, the memories will follow in the baggage car."

Assuming I have the correct model #28540, the ac regulator is part # 691ACRGF04 ($30).  Lionel's 1/2 price sale is the weekend of Nov 2nd.  The grill is not separate from the shell.  The shell is only available from North Lima Train Works.  Its part # 6208540007 and North Lima has the part for $125.

Since the smoke unit overheated, you may need to replace the smoke unit as well.  The smoke unit is part # 6308031200.  Its also $30.  But you can get 1/2 price on Nov 2nd.

You can check all this out at


You only may need to replace the PCB on the smoke unit, no need to replace the whole smoke unit for this failure.  The sticking point is I don't see the PCB listed separately for this smoke unit.

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