I've had many mantua and other similar locos do this to me. The problem lies with the gear meshing. Try adding slips of paper between the motor and frame
I am late to this discussion but have run across this issue on several Mantua steamers.
When you were cleaning, did you polish the bolsters and trucks on the tender? It seems the contact points stay clean while doing forward work but when you go into reverse the trucks make a tiny shift on the bolsters and apparently a bit of corrosion comes into play; causing these issues.
But most of the problem can be traced to the crappy motor used in those engines. The "power drive" versions were better but not very common. I would be looking for one of the factory replacement can motors on the angled mount with the worm gear on the motor shaft. Its a bolt in replacement and will improve that models running 10 fold.
Here is a Helix Humper kit https://www.ebay.com/itm/324811852116?hash=item4ba04b8954:g:ypQAAOSwX0BhV7bW
Here is the stock Mantua can motor set up. https://www.ebay.com/itm/144227738359?hash=item2194a4a2f7:g:4y8AAOSw80phVxiv
Silly NT's, I have Asperger's Syndrome
Back in my pre brass loco days when I ran more of the Mantua engines. I found than many of the rods, which are stamped out of metal, had burrs and such around each opening. I took the time with a magnifier and a jewelers file set to clean up every single hole. My worst offender was a brand new Booth Kelley Logger 2-6-6-2T that I got for Christmas from my parents. That took alot of time to smooth out. A combination of cleaning up all the burrs on the rods, a GSB Tan Can motor and lots of run time on the club layout. It was as smooth and quiet as a Kato locomotive, all you heard was some light clicking of the side rods. I only wish the boiler/side tanks on those were diecast metal instead of plastic. Mike
If it's jumpy going forward, there could be a minor quartering issue in the drive wheels. When you take the motor out and roll the chassis on a piece of track or turn the wheels by hand, do you feel any binds in either direction?
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BTW, a few companies have offered a can motor upgrade for these older Mantua models. The Helix Humper was one that was around for a few years, had a flywheel with the worm machined into it on some models, sadly they are out of business but the motors pop up at shows and ebay. Then the later models had a can motor with worm gear on it that is a direct bolt in fit for the old open frames that are notorious for poor running qualites either from excessive motor shaft movement to weak magnets, both of which can be fixed, but its still an open frame motor.
NYcentral54:
Run the locomotive in both directions to make sure the squealing issue is gone.
Sometimes excessive end-play in the motor can cause such problems. It's a pretty easy fix to add some thrust washers on the motor shaft to limit the end-play.
Wayne
Thank you for the advice. I replaced the motor and worm gear with a NOS replacement motor. Same problem. I will check the gear mesh. It is an open worm/drive gear setup.
Thankd for your help.
The gears are probably not meshing properly. This can be caused by a few factors. When removing the boiler, can you see the bull gear and worm gear, or is this a covered geared system (I think Mantua called it the power drive)?
Simon
Oks it possible being that old that the gears have enough wear that they are binding?
A pessimist sees a dark tunnel
An optimist sees the light at the end of the tunnel
A realist sees a frieght train
An engineer sees three idiots standing on the tracks stairing blankly in space
Larry,
When you lubed the engine, did you do the two motor bearings?
I'm assuming the motor setup looks like this, with the worm on the motor shaft:
Ed
I have a Mantua 2-8-2 Camelback from the 1980's that has a running issue. The locomotive runs fine and very fast in reverse but is sluggigh, slow and jumpy in forward. I have cleaned the wheels, bearings and lubricated the engine but the condition still exists. Does anyone have any idea of the cause or a possible solution to this problem.
Thank you,
Larry