# Strange issue with MTH 30-1554-1 Southern 4-6-2 Imperial P47 Smoke Unit



## L0stS0ul (Feb 6, 2015)

I picked this engine up a few weeks back for a great price and it runs great but I'm seeing a really strange issue with the smoke unit. 









When I got the engine I took it apart and it looked like someone had swamped the thing with smoke fluid at some point. There was fluid all over the inside of the train but everything in the smoke unit was dry. When I pulled it apart the top gasket crumpled and ripped a bit but is still usable. The gasket between the motor and the reservoir was also a little smooshed but I fixed that as well. Finally, I pulled out the smoke wick and put a new one in and primed it.

Since then the train will smoke awesome for about 10 minutes and then you will start to see the smoke volume drops quickly and then just stops all together. The faster the train is moving the faster this occurs. At first I thought the motor was dying or the smoke unit shorted out but after testing everything that wasn't it. I figured out that if I stick a toothpick down the stack it will start smoking again. It looks like somehow a bubble continues to form blocking all airflow. 

I have re-packed the smoke unit probably 10 times and I can't figure this out at all and I have never had this issue with my other trains. Any ideas?

Thanks!


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## gunrunnerjohn (Nov 10, 2010)

When you say you "repack" the smoke unit, are you using the MTH braided wick and putting it between the two resistors in a single loop? The key here is the wick should not block the airflow between the fan chamber and the stack. The fan should blow air over the resistor and wick to move the vapor to the stack. That particular unit uses a stock MTH smoke unit and shouldn't have any special issue with bubbles forming.


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## L0stS0ul (Feb 6, 2015)

Hi John,

I am using the MTH braided wick. I pinched the wick together and placed it between the resistors. The top gasket had formed a bubble in between the resistors and the top of the smoke unit. I removed the bubble by pressing it back up against the top of the unit. The only thing I can think of is that it's the gasket being ripped up a bit causing fluid to wick towards the smoke opening. I can't find replacement gaskets on MTH's website though. I can take it apart again and take some pictures so you can see what I mean. 

Thanks


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## gunrunnerjohn (Nov 10, 2010)

Many times, if the gasket has formed a bubble inside, I just cut it away. You only need the part that actually seals the sides of the smoke unit. I've also been disappointed that I can't get the MTH smoke unit gaskets nowadays. I'd like to find some rally thin gasket material to be able to make them.


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## L0stS0ul (Feb 6, 2015)

I'll try cutting away some material and see if that helps. Thanks John.


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## gunrunnerjohn (Nov 10, 2010)

The gasket material swells and sometimes causes issues. When it's over the fan, sometimes it extends down and stops the fan.


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## L0stS0ul (Feb 6, 2015)

I took the engine apart tonight and cleaned up the gasket. I think it was shredding near the smoke exit hole which was allowing the smoke fluid to wick. I cleaned the whole area near that and then put the unit back together. Here is what it looked like before cleaning. The gasket really ripped apart









I didn't get to test it though. As I was putting the top back on the thick blue wire came out from the circuit board that is attached to the boiler shell. As far as I can tell this wire was not part of any of the wire harnesses but I can't figure out what it was attached to. If it broke off it was a really clean break. The wire does not appear to be attached to anything else within the engine. It is attached to the wire harness for the tender connection in the back. It is the thickest wire in the train. Any ideas where it goes and what it does?


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## gunrunnerjohn (Nov 10, 2010)

That wire goes to the mux board mounted in the shell. It solders under the board to the negative side of the 47uf 35V capacitor that's in-line with the connector at the end of the board, the one right on the corner. If you look you'll probably see evidence that it was connected there. The negative pin is the one with the stripe, toward the inside of the board.


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## L0stS0ul (Feb 6, 2015)

Thanks John, I couldn't find a wiring diagram for this engine. I'll pull the board up and check it and get the wire re-attached.

Any idea what symptoms the engine would have if this wire was not connected? I'm guessing it has not been connected for some time as I didn't pull it or anything it just fell out of when I flipped it over this last time.


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## gunrunnerjohn (Nov 10, 2010)

I don't have a clue. It seems like an after-thought the way it's wired in. It's a large ground wire, so I'm assuming they were having poor ground issues and that was the kludge solution.


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## L0stS0ul (Feb 6, 2015)

Funny, hardware hacks are always the most interesting  I didn't get a chance to look at the engine tonight but will hopefully get it resolved tomorrow. Thanks again


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## L0stS0ul (Feb 6, 2015)

I got the wire fixed. Wasn't too bad. It does look like this engine has had some work done to it at some point. Easy enough to solder the wire back on. 









Still having trouble with a bubble forming over time. It's taking longer now that I've cut some of the material away but it is still forming. Not sure what I am doing wrong. Are there good instructions somewhere with pictures of video of how to install a wick in MTH engines. I think I'm doing it right but maybe I'm missing something.


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## gunrunnerjohn (Nov 10, 2010)

Let's see the pictures of what you're doing. It's generally not that difficult. How much fluid are you using?


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## L0stS0ul (Feb 6, 2015)

I'll pull it apart tonight when I get home and take some pictures.

I use megasteam and I have some MTH fluid that I also use from time to time. I find I get much whiter smoke with MTH but the smell is extremely strong. Megasteam might not be as white a puff but the scent is much less strong and pleasant.

When running the MTH trains I usually put between 15 and 20 drops in when I'm starting everything up. Then when the smoke volume drops I add another 5-10 drops. That is usually after about 15 minutes of running. MTH trains seem to eat up the smoke fluid a lot faster than lionel but the smoke volume is quite a bit more

Each time I have pulled the 4-6-2 apart the wick has been mostly dry. The wick is charred where it touches the resistors but that's got to be expected.


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## L0stS0ul (Feb 6, 2015)

I finally got around to messing with this today. I think there was a combination of 3 things going on with this smoke unit. 

1. The top gasket is letting air out since it is destroyed. I can see huge puffs from time to time from under the engine. It kinda looks like steam from the cylinders. By itself not a huge deal but it was adding to the problem

2. The fan blade looks like it's from a lionel unit and I think it might have also been slipping on the motor shaft. Compared to my other ps2 engines the original one has more blades and looks like the same one I have on my lionel engine. I accidentally broke one of my other MTH engines smoke units in this investigation so I scavenged the fan blade from that one to use on this nicer engine. It fit a lot more snugly

3. The top gasket was wicking smoke fluid towards the smoke opening.

Just to be complete here is a picture of how I have the wick in the resistors









Because the fan blade was slipping and the top gasket was leaking air there was a low pressure situation in this smoke unit. Once I cut away the top gasket and put the tighter fitting lower blade count blade on I have not had the bubble form. I'm still getting the cylinder effect from time to time but without a replacement gasket I'm not sure I can address that completely. I've only run it for 15 minutes so far but I think fixing 2 of the 3 issues might have resolved this. Fingers crossed.

Now onto my other issue. In taking apart one of my other MTH engines to investigate I accidentally broke one of the resistors. I believe the smoke unit is part number AA-0000029. I need a new fan blade for it and a new resistor. I also need the gasket that goes between the fan motor part and the smoke fluid area. I scavenged that for the other engine as well and I'm having trouble finding a replacement. Anyone know where I could find these parts?

Thanks so much

Picture of the broken resistor


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## L0stS0ul (Feb 6, 2015)

I think I found the model number for the smoke unit gasket and MTH even says they have some in stock 

IB-0000006

http://mthtrains.com/IB-0000006

It looks like the right from the picture. I'm not even sure which smoke unit the 30-1554-1 Southern 4-6-2 has as I can't find a parts diagram for it.


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## gunrunnerjohn (Nov 10, 2010)

All of the common MTH smoke units, including the one in our pictures, use the same 16 ohm resistors in pairs. If you send me a PM, I have the proper resistor and the official MTH impeller for the smoke fan. I also have the gasket that fits between the smoke chamber and the fan chamber.

FWIW, AFAIK, the MTH and Lionel smoke impellers are virtually identical, and have the same shaft diameter. They do tend to get loose as they age, nature of the beast.


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## L0stS0ul (Feb 6, 2015)

Thanks John, PM Sent.

This was the fan blade that was in the unit. It's got 8 blades and was barely holding onto the motor shaft. Slide right off without any pressure. The one that was in the other MTH engine had 6 blades and the blades were about twice as thick as this one pictured. My other MTH 2-8-0 has the same 6 fan blade setup. The 6 blade is working a lot better in the engine for sure but hard to say if it's just because it's holding on better or not.


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## L0stS0ul (Feb 6, 2015)

Well, I'm at a loss now. I have replaced the both of the gaskets and the fan impeller. I have also replaced the resistors while I was swapping out the gasket. Why not I had them off anyway. The only thing I can think of now, as I have replaced pretty much everything, is something with the brass smoke exit thingy is collecting smoke fluid and forming a bubble. I was thinking maybe cleaning it with dish soap or something else that would try and resist bubbles. I have noticed that it tends to form bubbles really easy when I am filling it which my other engines don't seem to do. 

I seem to have the really strange issues a lot lol. I really thought I had solved this one. Here's a video of it after getting everything back together. It is smoking awesome and literally, as I turned off the video, when it came out the other side of the mountain no smoke was coming out of the stack and the bubble had formed.


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## gunrunnerjohn (Nov 10, 2010)

The one thing you can do is take the brass ferrule out and enlarge the hole as much as possible without cutting through the threads. That one should have a screw-in ferrule.


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## L0stS0ul (Feb 6, 2015)

This one is screwed on. I will check it and see what I can do. It is pretty thick so I'll take a look and see if I can enlarge it. Probably give it a good douse of WD-40 as well and the a silicon bath lol. :goofball:


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