Mikado Jr fan issue.

First thing I do is connect the fan motor by itself to a DC source, I like to use around 3-4 volts.  The voltage they normally run on is 5VDC, but if they won't run on a lower voltage, they're probably on their way out.

 

I've had excellent luck lubing the fans, though it doesn't always fix them.  The motors are only around $6, so replacing it isn't a costly procedure.

 

If the fan is good, then you'll have to chase down why it's not getting voltage.  Specifically, which model is the problem child?

Hi John, 6-11100 Penn. 2-8-2 Mikado Jr. #9631 with TMCC. 2007. Railsounds 5 Looking at the parts list, it looks like there is not a fan but a smoke piston. Do these pistons stick? Or do they have seals that fail? Starting to think that it is only a plunger, spring and some sort of cam. May have to take it apart after all.

If you still have chuff, then the smoke lever is OK. You could have a stuck piston, plugged air hole or you might have to change the batting and resistor. Possible bad triac on radio board, could be smoke switch turned off. Also try re-programming.    Just my thoughts.

 

Bill

Hi Bill, Turned out to be any easy fix. 4 screws and about twenty minutes. Removed shell. Noticed that a spring was loosely draped over lever. Did not make sense and I assumed it was a return spring. Looks like someone was inside and did not reassemble properly. Put spring inside and guessed that the thin washer goes between the spring and the piston. Put it back together and smoking away. Only thing I noticed is that I am getting some smoke blow by down by the steam chest. I was wondering if the ball bearing check valve is leaking. I am wondering if maybe that thin washer is supposed to be attached to the piston by the little "ears" that have a small screw in them. I initially thought that it was just a retainer for the ball bearing. Anyone have a diagram? Also thinking that the piston just may be a sloppy fit. Does not actually look that bad. Almost looks intentional.

If you have a "PUFFER" smoke unit, it's most likely that that small, thin washer goes between the smoke unit and the boiler housing on the inside of the shell. This would seal the smoke unit to the body and not let smoke course down around the top of the smoke unit as it puffs, giving you that wisppiness of smoke that you are seeing.  Try it.  Hope this helps,  Dennis M.

Hi Dennis, Will try that. Because it was on top of the piston. Maybe this guy took it apart, got sidetracked and just forgot how to put it back together. Because this is not "wispiness" but when I stop fast, it looks like the steam chest is dumping a lot of steam. But it does not look like it belonged floating on top of the piston anyway.

If the ball in the check valve sticks, you'll get more smoke blow-back than if it's working properly.  When you shake the piston, it should freely rattle inside.  If it's clogged, you can remove the little retainer for the ball and clean things out.

Hi John, I'm going to take it apart tonight again. I believe mine has 2 ball bearing in the check valve. Both rattle freely. I'm going to put the washer on top where I think it belongs. As I said previously I don't mind a little blow by because it almost looks prototypical. I will post an update later on my results. Otherwise it a nice little engine. I may decide to install a cruise control. FMH

Took apart and put washer on top where it belongs. Two ball bearings in check valve freely moving and seats look clean. Inspected piston and look ok. No excessive wear marks or scoring. Fit seems somewhat loose but not sure what actual clearance should be. Not going to bother measuring with calipers. Still leaks. Watching closely, it does look like it is blowing past the piston. But it is not like there are compression rings on this thing. And more than enough is coming out of the stack.

I had one of these and I replaced the resistor with lionel 8 ohm and new wicking. I also made the air holes bigger. It was a better smoker after that. I did have some smoke coming out the bottom as you are having. I belive it is the diameter of the piston that causes this. Just a by product of lionel puffer smoke units.

What air hole did you make bigger? Is it at the top of the piston chamber. If so that might work but it may also decrease the out put pressure with the trade off being and increase in volume. If so what size drill did you use? According to the website this has a 20ohm 5 watt resistor already. I assume that the piston takes in air via the check valve. When piston drops, balls lift and air sucked in. And without a tight seal around piston, air also enters the same way that the smoke escapes but in reverse. I am sure that the leakage occurs on the compression stroke. As I said above. Smoke output is not an issue. I just leaks past piston. But as you said, just a design limitation. Not much more to do but pretend it is just steam chest releasing pressure. Thanks all. FMH

Do you have PRR Mikado Jr 6-38616?

6-11100 See a few posts back.

The smoke unit resistor that was in my engine was ceramic coated. So I replaced it with a wire wraped one. I belive it was an 8 ohm. As to the holes. As you know the piston is mechanically moved up and down buy the lever below it. So it moves the air unlike a fireplace belows into the smoke chamber via the two hole type posts in the fluid chamber. If you enlarge the two holes just a tad the piston can move more air into the chamber. More air flowing over the hot resistor when in operation produces more smoke. fan driven units put more air into the smoke unit via the fan and its fan blades thus making more smoke output. what the piston types do is mechanically force a puff of air into the smoke unit via the mechanical piston. so the more air flow you can get into the unit the better. thus enlarging the two holes inside the unit helps with the air flow.Also replacing the stock wicking material with new lionel material is help full for two reasons. one You can get a little more fluid in the unit and two the new lionel wicking material does not charr as fast as the stock material. All this in conjuction with a hotter resistor in the command enviroment makes for better smoke. Hope you can follow me on my description. Try this experiment.... Take a petri dish and put some lionel wicking material soaked good in smoke fluid in the dish. Then place a hooked up resistor ( use test leads hooked up to 18 volts) down in the fluid soaked batting. Make sure its down in the wicking material first or you will burn it up. Then just blow over the resistor with your mouth. See how much smoke you get. This is why the more air blown over the resistor in the smoke unit when in operation the better it smokes. This is why fan driven units put out more smoke than piston type units. I may not be 100% right on this, but I believe I am close as to how smoke units work. Hope this all helps.

It makes sense about the resistor. And the wire wound is providing more heating surface. Within reason of course. I am wondering if the board on the older TMCC unit can handle the addition current. The new wicking also makes sense. And opening the hole on the fan units makes sense. Because the fan can clearly push more air. I guess theoretically, too much air would actually cool the resistor reducing smoke output. But not sure if the same logic applies to the puffer unit. For a fixed size piston chamber, the volume of air exiting on the compression stroke does not increase with a larger exit hole , only the pressure at the outlet. Assuming of course a complete discharge per stroke. And the size of the holes need to smaller than the check valve on the piston, otherwise we would be back to the original problem with the piston sucking from the path of least resistance instead of pulling in air from below, it would pull smoke away from the stack into the cylinder. Maybe you could clarify what you mean by a "tad" I am used to fractional, decimal and # drill sizes. And any feedback on what is the smallest size resistor that is safe to use.

Correction I may have implied that increasing the hole size increases the pressure it actually decreases the pressure

Increasing the cycle rate or the cylinder size is the only way I can see that you would get more air per time unit into the smoke unit with that puffer system.

Actually, with all the blow-by around the cylinder in a typical puffer, increasing the hole size may well increase the smoke volume.  By reducing the pressure in the cylinder, you reduce the blow-by around the cylinder and increase the amount of air volume going through the smoke chamber.

 

You would think someone might come up with a wick less smoke unit. A simple metered spray mist directed at the resistor. Use the empty wick cavity as a collector/ reservoir with a sump recovery. A PCB to calibrate/ control the the injector and resister. Still use the fan to pressurize the unit but use a mechanical valve to time the puffs. Might work and be made cost effective. Maybe on high end initially.

I'm guessing it would be expensive to make a mist based unit that was reliable. 

 

I'd like to see them simply make the reservoir larger so you could go longer before you had to refill the smoke unit.  The MTH method of sandwiching the wick between two resistors and sticking it into the bowl works great, as can be seen by the smoke volumes.  If that bowl was larger, you could lay down a fog that you couldn't see through before you had to refill!

 

Hi John, I was considering that also. But in order to get blow by, the smoke needs to get in the cylinder. And it can only come in from the smoke chamber holes. Which would indicate that instead of outside air entering only from the check valve which is working and from the piston clearance, smoke is getting sucked into the cylinder. It is possible, but not sure if increasing the size of those holes will actually get more air to the smoke unit or just more back flow. An additional check valve in the smoke unit with a larger hole might work.

Hi John, My older MTH makes tons of smoke. But it is a continuous fan with only TMCC on and off. Smokes moving or standing. Is there a simple ( inexpensive) way to get the fan to pulse/ chuff? Does not need to be in sync with sound but would nice.

There are a lot of factors at work here, and the check valve is certainly one issue, it's pretty small.  When the piston travels down, it will suck from the smoke chamber, and indeed is usually does.

 

A much better design would be a tighter cylinder fit and a better check valve.  That  way there would be more air available on the upstroke.

I agree. a check valve with a bypass valve for air intake on the exit port would be much better than the check valve on the piston.

Is there a part umber for the improved wicking on the Lionel website. I need a few odd bits anyway. So I might be able to justify the nine dollar shipping. Fred

Fred,

 

   I have both batting 691-SMKP-008 and 691-SMKG-KP5 at 15% off list price and a lot less  for the shipping.

 

Bill

Hi Bill, I do not know what the difference between the two part numbers are. Or how to order from you. A few more details would be helpful. Thanks FMH

 

Fred send us a email.

 

Bill

Will do in the AM Thx