Marx SF 21 Diesel-Need Advice

Classic Toy Trains Forum
1

I recently got a Marx 21. It ran great after cleaning the wheels, track, commutator and pickups. Today it started to run fine, then would stop and reverse, then back to forward. Where can I start? I sprayed contact cleaner in the e unit, no good. What would you Marx pros do out there?

Thanks much

Northernpike

2

NP, I had a MARX 21 some years ago and it was a nice loco for sure. Without seeing your loco, the trouble you describe sounds to me like a loose wire some where on the loco - either off the reverse unit or off the motor. Maybe even a break in a wire coming off the power truck. A loose wire off the reverse unit can vibrate just enough when the train is moving to cause a momentary break, which can cause a change in direction of the loco.

It’s not uncommon for locos with metal frames with holes stamped in them for wires to run through, to eventually over time develop a break in them, or for the wire coating to wear off at some point. When the loco is going around a curve, the wires move and if they come in contact with the metal frame, they can momentarily cause a short, which a can trip the reverse unit.

I’vbe had this kind of problem in the past with older postwar locos. Checking out and replacing a wire or two usually fixes the trouble.

3

brian

Thanks for the info-I will have to check those wires-makes sense

I will keep you posted. Thanks much!

4

Most times what you describe is caused by something being dirty. But you say everything is clean so as mentioned above wires would be next or the reverse unit is shorting from time to time. If the unit has loose parts they will arch.

5

I have two #21’s and they both have been examined and cleaned but they both do the same thing you describe when passing over switches. I made a special loop with no switches just so they could be run from time to time. If you find the problem with yours please let me know what corrective action you take.

6

Got it running. One of the wires on the pickups was loose, vibrated causing interuption in power and the e unit cycling. thanks for the advice

northern