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I don't know if anyone has done this, but my dad has the 783, but it only runs around the Christmas tree and he isn't very good at keeping the smoke unit wet.  If I purchased a used unit that may have fit in the original 773 with the same type of old style heating element, do you think this would be a pretty easy, low modification swap?  I know we'll lose the steam chest smoke, but that's not really a concern.

Any thoughts?

As always, thanks!

Last edited by Larry Mullen
Original Post

As long as the element isn't board fed, I don't know why it wouldn't work.

It may take some fidgeting of wick and positioning but is worth a try if you keep burning out the liquid elements. (red auto hi-heat silicone can take the heat if you need to attach, make, or fill something )

You might want to note the normal operating voltage of the loco and then taylor the ohms chosen to that voltage for good smoke heat @Xvolts

It's certainly possible.  But I agree with Adriatic, I'm not sure that it's necessary.  Unless you've already converted your 783 to command control, or you're constantly running it at 16-18 volts to pull a bunch of lighted cars, it's very unlikely that you'll "burn out" the original fluid smoke unit just because it runs dry.  That's more of a concern with the newer "wick-type" smoke units typically found in high-end command controlled locos.

By all means do what makes you happy but if it were mine I would keep it original.  My $.02.

I guess I misunderstood.  If you're concerned about burning the unit out from running it dry, you can leave it alone, or even take the loco apart and disconnect the wire.

If your goal is to get more output, that's a different problem.  I've never heard of burning out an MPC-era fluid-type unit.  But if you install a new element with wicking, now you're back to the risk of burning it out if it runs dry.  

Besides the unit from the postwar 773, there are MANY options to make your smoke more prolific.  Search the forum for Gunrunner John's SuperChuffer.  Good luck, whatever you decide!

Not hard to replace smoke resistor if it burns out.  Do get rid of the wick sleeve...they scorch,  get hard and won't absorb much fluid. The loose wicking works better.  When I took mine apart,  I did a modification I'd read of in the past...I think Jim Barrett recommended it. The advise was to drill a small hole about 3/16' in the partition between the 2 chambers in the unit.  The partition is part of the unit's top and is easily accessed when the top is removed. I did this to mine and it improved smoke output significantly.  The smoke unit in this engine is not fan driven so I don't believe the Superchuffer will  work with it...but I may be wrong.  Best to check with John on this.

 

Here's some photos of my 783 smoke unit taken apart.  I found that the smoke element was broken in 2 but the wire was still intact so it functioned but I replaced the element.  Soak the wicking material with fluid before putting it back together and make sure to install the gasket between the top & body.  If it's missing, you can use some RTV type automotive sealant.  I also cleaned the wheels and lubed it while on the bench. 

IMG_3172

Drill the 3/16" hole in the middle.

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Wicking material in place.

IMG_3174IMG_3176IMG_3177

Soak the wicking before reassembly..this keeps it from charing on initial heatup.

IMG_3178IMG_3179

Test continuity and resistance before reassembly..it's a 27 ohm resistor(approx)

IMG_3180

Lots of gunk coming off the wheels.

IMG_3182

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Images (9)
  • 783 Smoke Unit
  • Smoke Unit Mod
  • Smoke Unit Wicking
  • New Resistor in Place
  • Smoke Unit ends Routed out the Top
  • Pre Soak Wicking with Fluid
  • Don't Forget the Gasket
  • Smoke Unit Resistance Test
  • Wheels were Dirty

It looks to be coming from a small hole in the lid,,,I plugged that hole up on mine.  Don't remember what I used ..maybe RTV.  I also pulled the manifold that routes smoke to the steam chests, plugged the hole from the chamber then replaced the manifold.  This makes most of the smoke come out the stack.

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