Mantua GP-20 problem

[Matt Probst]

Hi all...
Gotta problem I'de like to give to all the expert Gaugers. I recieved an older model, hand-painted Mantua GP-20 off E-Bay. For 20 bucks I couldn't go wrong! (Righhhht)....As always had steam power, I don't know squat about diesels. My only other one is a Walthers SW1 which I love.
I put the Geep on the tracks. It hummed but didn't move. I cleaned up the filthy wheels and re-lubed. It hummed but didn't move again. Hmmmm I took out the power truck and inspected it. Aha! An itty bitty screw was stuck fast to the magnet. Removed the screw and tried to figure out where it came from. No luck...all parts seemed to be in order. There did not seem to be a screw missing anywhere . Checked all the wires and they seem to be fine. The only one I couldn't see is the wire where it attaches to the rear truck. Tried to figure out how to remove the rear truck. Couldn't get the shell off the chassis. The tabs wouldn't move! I didn't want to force it as my mini screwdriver was beginning to mar the plastic. Inspected the shell and saw that the light bulb was still in it's clip but don't know how to re-attach it to where it's supposed to be . But that seems to be a separate problem. Cleaned all the wheels again, re-assembled and set it on the tracks. This time it ran for about 12", stopped and hummed again The back wheels sparked a little and that was it. Now what? What's my next step? Off to the hobby shop? Or is there something else I should check or do? Thanks in advance for any suggestions.

Matt--Hershey, Pa.

 

[Ralph]

Hi Matt,
Wow, good ol' 5628! I'm not sure you'll want to know this but I've owned one of these for years (it was a hand me down from an uncle) and found it to always be a poor runner. It tended to stop on turnouts (only four wheel pick up I believe) and it ran smoothly only at unrealisitically high speeds. It really growled at low speeds! I thought about trying some maintainence on the motor but the powered truck doesn't have screws you can remove to gain access to its parts. Its all sealed up in there.

Removing the rear truck IS hard and I take a breath when prying the shell off. Just in case you didn't notice it, there's a tab in the back end of the rear truck chassis that inserts in the shell above the rear coupler. Maybe that's making the job harder? The clip for the light seems to attach to a small post in the ceiling of the engineer's compartment.

Another thing you might not want to hear is that just last week I gave up on bringing this loco up to speed as a powered unit and replaced the powered truck with a free wheeling one (from another Mantua unit) to create a dummy unit. Since I'm modelling Penn Central I sometimes like to run mixed consists of Pennsy, NYC, and PC power. I reason that the paint shops haven't gotten to all the locos yet.

Cleaning the wheels big time is about the only helpful advice I can offer. Hopefully some one will have better technical ideas!
Ralph

 

[Roger Hensley]

I hope that the seller kissed you. It would have been nice to have gotten something for the money.

I liked the old Mantua even tho they were fast, irratic and noisey. I have a couple of the power units in my parts box (no, they're not for sale) for use in a couple that I have for display if they are needed. Indeed, I even changed out Tyco power units for the Mantua ones for my kids when they were young.

Frankly, it sounds as if you may have a bad winding (wire) in the motor. The loco stops and hums...

Well, other possibilities:
1) lube the ends of the motor (no oil on the bruishes!)
2) lube the axles where they enter the truck frame
3) It picks up power on two wheels on the front truck and the opposite two wheels on the rear truck. The oil will help make electrical contact.
4) the bulb holder pushes on to a little tab on the inside top of the shell. If broken off, you will need to super glue it in place.
5) as mentioned, you actually spread the body (carefully) to remove the trucks and you will have to remove the power truck to lube it correctly.
6) the wires from truck to truck run under the weight in the center of the bottom which makes it a little hard to work with. Removing the weight exposes everything.
7) Pull all of the stuff out from under the shell and replace it with a modern locomotive chassis if you really want the unit to run well. I like the NYC shell myself and would work it over to get it to work one way or the other.

Good Luck

 

[Vic]

Its A "Booger" To Fix !!!

Hi Matt, Back when I had the hobby shop hardly a week went by that one of those didn't show up with the exact same problem. The problem is that little tiny gear on the motor shaft that turns a larger flat gear. The little gear is slipping on the shaft. It gets mis-aligned and locks up the power truck. Like the others have said you have to "poke and prod" to get the power truck out but it will come out of the shell.

Since that little gear that slips is made out of nylon there's not much that's gonna hold it to the shaft. Super glue does not hold to nylon well ... sometimes it will and sometimes it won't.

Slid the little gear off the motor shaft...clean the shaft with a Q-Tip and alcohol to remove any oil. Slide the gear back on making sure it mates correctly with the large flat gear and then put just a tiny drop of super glue on the shaft hole on the small gear. Let it sit for several hours so the glue can "wick down" between the bore of the gear and the shaft. Then re-assmble everthing and give it a try.

Like Roger said there may be a bad winding in the motor. Lots of times when the power truck would lock up from the mis-aligned gear it would overload the windings of the motor and burn one of the armature windings.

This isn't a guaranteed fix...you are better off trying to find a junked out power truck ( they were common to all Mantua/Tyco locos) that has a tight fitting gear and use it to replace the one on your loco.

I got so tired of trying to fix those things that when someone would bring one in I would tell them that the only thing I could do was to replace the entire power truck at $13.95 plus $10.00 labor. At that time that was more than the cost of a good Athearn loco so I would give them 15% off on a new loco of their choice.

A couple of times I did make a decent running loco out of one of those by adding a second power truck....made it dual motored...they would run slow and rather smooth that way.

Hope this helped

 

[Matt Probst]

Ralph--Roger--Vic as always; Thanks for all the wisdom and advice as usual!
I don't think I'll order another loco off E-Bay w/out checking with The Gauge 1st!
I've e-mailed the seller in regards to the loco in the hopes I can return it for a credit. If not, I'll try to either fix it myself by one of the above methods or use it for a clay pigeon. (Pull!!................Boom! ) I didn't realize Mantua/Tyco has had such problems with locos. I thought they were "mediocre" not "junk". (Come to think of it, I used to have a Mantua 0-4-0 PRR switcher that ran like a top).
But anyway, at this stage, I try to devote as much MRR time into layout building and not much with mechanical tinkering other than usual maintenance/cleaning. If I get a loco it BETTER at least run!!

Matt--Hershey, Pa.

 

[DanRaitz]

Matt,

If you want a good inexpensive diesel locomotive you can't go wrong with the standard Athearn. You will pay anywhere from $33.50 for an F7A up to $59.60 for an SD40-2. They will run forever and are easy to repair if you have to. Granted they are not as smooth or as quiet as Kato's, Atlas's and Life-Like Proto-2000's but then they are a lot less MONEY.

Dan Raitz
Escondido, CA