New motor and sound decoder in Athearn challenger

[mmagliaro]

There was a problem with the early-run Challengers wherein they were overlubricated, oil got onto the commutators, and it caused excessive comm slot clogging.  The symptom was exactly as you describe: motor starts okay, but once it runs for a few minutes and heats up, you start getting intermittent slow-downs and finally a completely stop.  It also gets hot and draws more and more current.  The phenomenon eventually destroys the motor, or at the very least, burns down the brushes to nothing.

Cleaning out the comm fixes the problem, but only temporarily, unless you clean out all the excess oil and brush debris from the motor cavity.  On the one I fixed, I cleaned out the slots, cleaned out the motor with brushfuls of alcohol, and then it ran great... for about 20 minutes, and then the problem reappeared.  I had to do it several times before I finally got all the oil out of there, after which, it would  run for hours without a problem, but even after that, at a few hours the problem would reappear.  I could only surmise that the brushes had been so contaminated with oil that they softened and there was no saving them.

I eventually replaced the motor with one from the Life-Like/Walthers 0-8-0, which is a 3-pole skew-wound.  That fixed it for good and the motor was a perfect fit.  Of course, you're not going to find those now, but....

Now that I see a photo of that motor.... you might try going with (ironically) one of the 3-pole skew-wound motors I've been getting off eBay to use for rebuilding old Rivarossi motors.

They look like a dead ringer for size, shafts, and brush contact placement.  These are pretty darn good motors in their own right.

Just look for FT-010SA motor  on eBay.  And buy a few... these are industrial surplus from China and you can't always count on every single one being good.

[peteski]

Or just clean the heck out of the original motor.  I just fill my ultrasonic cleaned with Naphtha, dunk the motor in it, then run the cleaner for a while.  That should degrease it completely and clean all the gunk in the commutator..  Of course after I dry it, I oil the bearings.

[mmagliaro]

Or just clean the heck out of the original motor.  I just fill my ultrasonic cleaned with Naphtha, dunk the motor in it, then run the cleaner for a while.  That should degrease it completely and clean all the gunk in the commutator..  Of course after I dry it, I oil the bearings.

I thought that would work, too.  Now, I didn't go to the extreme you describe, but I did really clean it a lot with alcohol and a brush, run it a little, clean it some more, etc.  And still, after an hour or so of running in the engine, the comm was loaded up again.  I have a feeling that the oil contamination permanently ruined the brushes, so that even after it is clean, they keep disintegrating rapidly and filling up the slots.  I don't have any scientific proof of this.  But I've never had a motor keep doing this after cleaning it out with alcohol.

[peteski]

I thought that would work, too.  Now, I didn't go to the extreme you describe, but I did really clean it a lot with alcohol and a brush, run it a little, clean it some more, etc.  And still, after an hour or so of running in the engine, the comm was loaded up again.  I have a feeling that the oil contamination permanently ruined the brushes, so that even after it is clean, they keep disintegrating rapidly and filling up the slots.  I don't have any scientific proof of this.  But I've never had a motor keep doing this after cleaning it out with alcohol.

Alcohol is a polar solvent, and while it will dissolve oil and grease (petroleum products), Naphtha (being petroleum based) IMO does much more thorough job.

But you have a point about the brushes. Excessive oil might possibly ruin them.  So, those could be removed and replaced while also cleaning the bejesus out of the motor "peteski style".