MDT Plymouth Switcher - sparks and smoke comes from front of motor

[FastKat]

I have a Burlington Route MDT Plymouth Switcher that is about 20 years old.  I put it on the track and it would light but not move.  I pulled the body shell off to see what was going on.  When applying throttle the motor would jerk maybe 15 degrees and stop... with a little hum.  If I turned the motor with my finger it would turn a little by itself but then stop.  When I put the throttle up farther I saw sparks and eventually smoke from the front of the motor.  The problem does not seem to be in the gears as they seem to turn freely but for the motor.

What is the problem?  Do I need to order a new motor or can this be cleaned?

I really want a Bethlehem Steel body shell.  Any chance they will be available separately?  Or should I just buy a whole new engine?

[brokemoto]

I would buy the newer version if for no other reason than the newer version runs better.   

If you simply must keep the old one, if you will get a bottle of Life Like track cleaner, dip a Q-tip into it (be sure that you get the Q-tip good and wet), hold the Q-tip against the armature and turn it with your finger, you will clean a bunch of crud off of it.   Put the chassis back onto the track, apply power and see if it runs.  It might sputter and spark, but eventually it should take off running.   if it does not, you have another problem.

To be sure that you have not done any damage to the motor.   As you mentioned smoke, that is a possibility.   It is not necessarily the case, older power often smokes if it has not been run in some time.   I do have one very old locomotive that smokes every time you apply power to it, even though I clean the armature.  There never has been any damage to the motor, it simply smokes for a little bit, then runs allright.  I know other modellers who have locomotives that do similarly.   Smoking is often a symptom of  a fried armature winding.  If you will inspect the windings on each pole, it usually is obvious if there has been any damage.   You will see charred wires and often the break will be obvious.   If that is the case, the motor is toast.  You can pay for another motor and do a swap out, or you can even pay to have the motor re-wound, but for this version of the locomotive, you would be wasting your time and money.   The latest versions of these things are not bad runners.

You might be happier with B-mann's GE 44-tonner or 70-tonner industrial switcher.   Either of these are excellent runners.   B-mann does issue at least one of these lettered for a steel producer, but I forget which one.   They come with a factory installed "smart" decoder that allows operation either on DC or DCC.   If you are not a DCC user and do not plan to be one, you do get much better slow speed control if you remove the decoder.   The modification is easy; there are tutorials on it in various places on the web.  Do keep in mind, though, that if you do modify the locomotive, you might void the warranty.

[gatrhumpy]

You probably just destroyed the motor. I would get a new one.

[FastKat]

Thanks for the info guys.  I will likely just look for another - perhaps the Plymouth MDT or the 44-ton switcher.

[swimmerbob]

The motors will fail if the brush holder gets overheated. if you've seen smoke at higher speeds and the switcher still runs, this is probably what's happening; the motor is no good. this 3-pole open-frame motor (somebody keeps referring to these motors as 'pancake motor'- not true- a pancake motor is one that has a flat, or disc-shaped commutator) is barely sufficient to power this switcher. it's used to keep this product within a particular price point. there has to be a better way without going to a can-type motor. what i did when one of my MDTs smoked itself, was get a surplus spectrum wide-cab (too new for my 60s layout) and use the motor and one of the sector worms from it. remove the flywheels from the 5-pole motor and remove the brass worm from one sector shaft. install the worm onto the new motor nose shaft and test the switcher with the body off. do not cut the rear shaft until you are happy with the worm placement and how it runs (sans body), since that rear shaft gives you a 'handle' for working with the motor until you are finished testing. when you're done, you can trim off that extra shaft and you'll like how your little switcher performs. i think mine runs as well as the can-motor MDTs the guys run at my club. If you are unfamiliar with working on tiny motors and shafts or don't have the tools and fixtures for such tiny work, get someone who does give you some help. Once you've seen it done, you'll want to dive in and do for yourself. If you aren't careful. you might have fun while learning!! good luck!