I’ve just purchased my first model train, a factory sealed Mantua 2-6-6-2 articulated.
Unfortunately it doesn’t run. The engine turns on, moves forward a half inch, and then seizes.
I was able to find an assembly manual for this kit but it wasn’t very clear on troubleshooting.
If anyone has worked on one of these before and has some advice I would appreciate it. I have previous modeling and wiring skills working with Gundam kits but this is my first time working with model trains.
Welcome aboard!
The problem with models “sealed in the box” is that, if they’ve sat for a few years (or decades), any lubricant in them dries up and becomes hard as concrete. Additionally, the wheels and some other power pickup components oxidize, weakening contact. Both of these can, in my experience, cause the results that you’re getting. I’d recommend that you take the entire drivetrain apart, photographing each step (I have good luck remembering how everything goes together, but not everyone does…), and then clean everything. Make sure to put some good lubricant on everything that moves (but keep it off the wheels) and then put it back together. This is a good thing to do with every model you get whether dried lubricant is the issue or not. If that doesn’t solve the problem, then you likely have oxidization. The locomotive appears to have a headlight (I’m unsure and not experienced with this particular model). When testing, keep an eye on it. If when the locomotive stops the headlight keeps on, then you probably have a mechanical issue. If the headlight shuts off, then there are electrical gremlins. Now, if neither of those solve the issue, I have to wonder if the siderods are binding. And that’s out of my little domain!
I hope that you can get the locomotive running–it really is a spiffy engine!
I have one of those models. They were made over 30 years ago, so for sure the grease has dried out and needs to be cleaned and replaced
Power pick-up can be a problem in any of those old Mantua / Tyco or other
pre-2000 engines. On those, the engine only picks up power from the track on one side, and the tender connects to the other track. It’s very easy to lose power and have the engine stop. (On a “modern” engine, the engine picks up power from all the drivers and all the tender wheels, making for a much better electrical conneciton.)A DCC decoder with a “keep alive” can help a great deal with that, or adding extra contacts.
So believe it or not, I took apart the drivetrain and everything was perfectly clean. No oxidiation and all the moving parts were fine.
What happened was there was a defect in assembly on the front cylinder timing rods. A couple of them were slightly bent so I filed down the rivets and it runs fine as long as I don’t put it in reverse.
I will get a replacement set of rods that aren’t bent eventually, but it does run now.
I disassembled the drivetrain and worm gears and everything was still clean like a new car 
It turns out they made a mistake with the front cylinder driving wheels during assembly and bent the hell out of the timing rods, so I will need to replace them eventually.
There’s nothing worse than a factory defect for making a model misbehave! Let us know when you get the new parts.
On a side note, how in the world did you upload that video?
I assume by “timing rods” you mean the valve gears, connected to the main and side rods. Most likely it was fine in the factory, but got bent (most likely bent in I would guess) at some point when it was being shipped to the wholesaler or retailer or to you. That happens pretty often with steam engine models in HO.
For the video, I used the media upload tab on the mobile browser, but the video was 20mb and the max filesize upload is 4mb, so I used an encoder to reduce the clip to 3.8.
Then just embed the video in the text post.
Huh. It’s consistently bugged out when I’ve tried to upload videos.
Assembly of the valve gear on that locomotive shouldn’t involve the ‘front drive wheels’, so I think what he means is that there was some problem with one of the lead driver pairs that slightly bent the front side rods.
For the OP:
In the United States the long rod from the cross head to the main driver pin, which in British parlance is called the same thing as in an IC engine as a ‘connecting rod’, is called a ‘main rod’.
If the engine has outside radial valve gear, it will be driven from an eccentric crank on the end of the main pin.
The long rod that works the valve gear is accordingly called the eccentric rod.
The ‘other’ rod that goes forward from the valve gear to the actual valve rod or spindle is called a ‘reach rod’.
That other stuff at the cylinders is the combination lever and union link, but I doubt if either of those would affect free movement of one of the engines on that locomotive.
Using that nomenclature will give us a clearer idea of what was misaligned at assembly that would be related to bent components.
I would suggest that a small jewelry ‘bending plier’ (with one curved and one conical jaw) might be useful for getting in and straightening various rods without having to remove them from the locomotive.
You may already have parts on hand to fix this. But, Bowser lists five pages of valve gear parts, maybe something in here you can use. Or not.
https://bowserorders.com/product-category/ho-bowser-parts-valve-gear/
You can find the Mantua parts diagram on HO Seeker.
