Seeking a suitable smoke unit for a broken down vehicle

I would go with a fan drive.  You can mount it under the table and just drill a hole to have it blow out from under the hood.  Depending how blown you want the car to look, either drill a hole and run the hose to the top, or let the smoke unit exhaust under the car and have smoke from anywhere. The fan drive will also have some pressure behind it, so the smoke will look more like the radiator let go or something, as opposed to a seuthe which will just wisp out some smoke.

A Ps1 smoke unit board can take higher voltages (and AC) because the step down is on the board.  The later units get power from the command control circuitry, so you need to feed it small amounts of DC.

Always a great scene, especially on older era vehicles. Do you want billowing smoke so that it appears the vehicle is engulfed with smoke? Or whisps of overheating? A Seuthe unit could be placed under the car, a blower unit with a hose you must be sure there is nowhere in the hose for liquid to puddle and block the airflow. To refill you just lift up the car in either case.

I'm thinking engulfed will get the attention of guests. wisps may be missed unless you're on top of the scene.  I have several runs under the layout. AC 10v ,14v  DC 3v,12v   Should be able to find something that works on one of those.

I'd go with the fan-driven PS1 unit if you can find one.  As noted above you can run it on 12V DC which of course is what you'll probably use for one of those eBay ~$5 timer modules that can be programmed to cycle 30 sec (or whatever) ON and 5 minutes (or whatever) OFF.  If you can only find a PS2/3 unit with separate fan and heater drive, you can use eBay $1 DC-to-DC voltage regulator modules to efficiently drop the 12V DC to the heater-resistor and fan-motor voltages.

Sounds like a fun project!  And speaking of "sounds", if you have figures standing about, why not have the timer also turn on a DC-powered sound module (eBay ~$5 in parts) with the hissing sound of a leaking radiator and dialog.

I'd have lower voltage to the PS/1 smoke unit, and probably adjustable voltage.  You'll have a bonfire if you run it at high voltage, you want it to be more realistic.  Also, it'll run a lot longer before you need to add fluid to it.

LOL picturing guests choking on the smoke, telling me my layout is on fire..... might just be a bit of overkill on smoke volume, huh?  but SOUNDS..... somewhere ..a long time ago, I came across sound modules that let you record your own. Gotta do that too.

Tons of cheap sound modules on eBay that allow you to record, I even have several types in my parts box.  When I see something interesting with electronic boards, I typically grab one or two.  Most of the time they're so cheap that I figure... why not?

Just ordered the fan driven smoke unit and the truck.  The only thing that I haven't been successful finding are sound clips of some mechanics having a discussion about a breakdown, or of the broken down truck's radiator hissing.  (Found one hissing clip, but they want a minimum subscription to a site making it the most expensive component of the scene).  Not gonna happen.   

I readily found many "free" MP3 steam radiator hissing sounds.  Even a youtube video for which there are several "free" converter programs - search "youtube to mp3 converter":

Many choices in sound modules.  There are all-in-one modules where you press a record button and it has a built-in mic to record/save a 30 second (or whatever) sound.  Then press the play button and it plays the sound over a built-in speaker.  Simple and effective.

I was thinking of the ones that play MP3 files from a micro-SD memory card.  For example:

In this case you apply DC power to the module and it automatically starts playing the MP3 sound file(s) on the memory card.  A 128 MB card is about $1 on eBay and would hold hours of sounds - more than you'd every need for a layout sound application.  Some modules can only drive earbuds so would need an external amplifier module (also about $1) but this has a built-in audio amplifier IC to drive a speaker.  

I assumed you'd need to mess with an audio editing program such as Audacity.  That is, you create your own layout sound by mixing the hissing sound with conversational clips.  Yes, finding "clean" audio conversation clips (without background music or whatever) can be hard to find.  I suggest making up some dialog and having some friends record it; hearing your own voice over and over can be un-nerving!  There is a learning curve to using audio editors so if this is a one-off, then probably not the way to go.

Youtube to mp3... kewl. Thank you for that!  I found this video of a...  hissing car radiator on youtube

Been looking for conversations about a breakdown, but yeah... although.... there's always  Harold and Kumar's tow truck driver scene   ...  LOL. 

Maybe the smoke unit from Lionel's burning switch tower. It will make plenty of smoke that will wiff up instead of shooting up using a motor blower smoke unit.

When I've had steam from a radiator, it shots up like a motor driven smoke unit.

The smoke unit is just below the truck below a flap of landscaped plaster cloth, with holes for the exhaust and fan draw.  I carefully drilled a hole from the underside of the vehicle into the engine space, cut a short piece of tubing (maybe 1/4")  on which the the truck sits to direct the smoke from the tube of the smoke unit into the engine space.

Looks perfect, just like the real thing!

I've been looking for a suitable speaker to go with a mp3 board. Most bay listings look like bare bones speakers without any enclosure. Does anyone have a link for a speaker similar to that in the picture Stan2004 posted above or a favorite they use for their sound applications?  

I use the speakers that come with ERR sound boards.  Since I install a lot of err sound kits, and for many of them, I use a larger 2" speaker and baffle, I end up with lots of little 1.5" speakers and baffles.  They're perfect for sound boards, and they have great volume for a small speaker.