Polar Express smoke unit fit question...

Thanks Alex, that's what I did. Just a little snugger. I'm typically a bit reluctant to start squeezing that stuff as I'm afraid to break it.

My mod of opening the two air holes from 3/32" to 1/8" didn't go so well. It makes so much smoke the puffer draws smoke down now on the down stroke. I should have stopped at cutting the sleeve off the resistor.

Jeff,

 There is a spring with a piston, the piston has two ball bearings inside. Check to see that the ball bearings are moving around freely. This might be the reason why the smoke isn't being pushed up and out the stack. It's okay too drill the holes larger, when I do it I only go one size larger.

Alex

I just went through this with a Christmas story steamer. Although, I didn't enlarge the holes. I did remove the resistor sleeving and changed the resistor to a 27 ohm wire wound. I had the same issue with the smoke unit creating so much smoke that it blew out of the smoke bellows on the down stroke.

The Christmas story steamer does not use a piston with ball bearings. I bet the polar doesn't have the ball bearing either.

I actually called lionel on this issue and asked if the piston with the ball bearings would help resolve the problem. The tech stated that it wouldn't.

So, I spent some time the other night and played with the smoke unit. The piston's diameter seemed to be a bit small. I decided to put a small nylon washer between the upper part of the smoke piston and the spring. The nylon washers was shaved down for a snug fit with the smoke chamber that did not cause a restriction of the pistons movement. (you must also check the thickness of the nylon washer you are using to make sure it doesn't jam the free turning of the wheels-aka-binds)

Although, It did cut down on the stack smoke a bit. The problem of massive amount of smoke bypassing the smoke piston was resolved. I still found the smoke to be very good.

Although, lionel did state the piston with the ball bearings would not help this issue. I picked one up at the Allentown show and was going to try it tonight....

I will let you know what happens. By the way----their is natural leakage form the piston acccording to lionel...I would try the thin nylon washer and see if it works for you.

What is the purpose of the ball bearings in the piston?

Jeff- You could try plugging one hole. My post war units only have one, and yours is oversized. Worth a try maybe.

I tried the piston with the ball bearings. It is smaller then the supplied piston..Not usable. The thin nylon washer is the way to go..Put between the spring and the piston.

I got it at sear hardware and had to shave the diameter down a bit. I kept the center hole the same. But, you could try enlarging it. No, leakage of smoke from the bottom.

Shawn - Could you post a pic of what you ended up with??

I checked mine and the piston does have the ball bearings Alex spoke of. I assume the bearings are to fill the hole in the piston on the upstroke.

Smoke fluid does have a tendency to get all over things as the piston and bearings in mine were coated. Even with the bearings and piston clean there was still considerable smoke coming out the bottom.

Off to try the washer.

The ball bearings are check valves to allow the piston to vent air on the downstroke so it doesn't pull the smoke down into the locomotive.  The smoke units without the valves usually have more smoke coming from below.  It does make a significant difference if these are not there or not working correctly.

OK - Tried the washer and still getting more smoke than I want on the down stroke. Looks like I'll replace the smoke unit and keep the drill away from it!!

Live and learn!!

You could try to put some thin material over the top of the hole in the piston that would act as a reed valve.  The valve would seal the hole on the upstroke and the piston would push the air through the smoke chamber and on the down stroke the material could lift and not have the piston pull the smoke out of the smoke chamber.

The washer must be larger then the piston diameter. I just tried it on a second engine tonight and it worked. The washer should be snug with just enough clearance to not be restricted. Is that what you tried. Or was the washer the same size.

Lionel also recommended cutting down on the wadding. I original used a whole piece of their string wadding. One of the tech stated about 4 inches..I believe this may have helped also.

I'm getting no smoke out of the bottom of the piston with the holes enlarge on the second engine.

Jeff,

I have both engines closed. So, supplying a picture is a problem. See , reply below.

Thanks Shawn. I still have smoke coming out the bottom so I'm going to replace the smoke unit. I did open up the holes, maybe a little too much.

Jeff, Fill the holes with epoxy (JB Weld) and drill to original size.  G