What are these strips of paper glued over the FM motors?

Could it be very old, dried out masking tape? I'd agree that someone added it for the reason you suggest, but not the factory.

Thanks, Bill. I wonder if that was common practice at service centers if it wasn't from the factory. The FM interior photo on the Tandem-Associates website has identical tape over the motors. 

In that case I'm looking forward to peeling these off and trying to remove the adhesive.

Matt, welcome to the forum!  That's a good question.  During the postwar era, paper was commonly used as electrical insulation in many applications.  I'm no expert on postwar locomotives, but your hypothesis does appear plausible to me: that it could have been factory applied to prevent the light bracket from shorting the motor circuitry or from rubbing the insulated wires.

Others more familiar with the older locomotives will probably have a suggestion or two about working around this.

The Tandem photo is interesting. Maybe it is factory. Your photo certainly looks the same.

I have a Lackawanna with the paper...I'am sure it was added at the factory....

Thank you! Sounds like this engine may never have been serviced, unless somebody glued them back very carefully. I am in awe at how smoothly it still runs though if that's the case.  The FM is living up to it's reputation thus far, thing is a beast. Thanks for the info and great to be here.

@Matt G from VA If you decide to remove the paper tape for easier servicing the of motor, maybe a good alternative would be to apply Liquid Tape to the underside of the lamp bracket.  The link above is to Amazon.  It can also be found in the electrical aisle of some home improvement and hardware stores.

I bought a FM a few years ago and it had the same tape. Ran very good also before I serviced it. Also had an original leaky battery.

The tape appears to have perhaps two functions - to prevent the chafing of the wires on the light bracket, and to provide a measure of strain relief on the motor wires. If you watch the motor pivot with the shell off on the O-31 curves this diesel was designed for, it becomes evident that keeping the wires tethered closer to the brushplate cuts down on the fatigue to the connections at the brushes and the field.

Jerry Williams did something similar by using a rubber band to cinch the motor wires down & around the can/enclosure to keep the wires from flexing at the motor solder tabs.

This is factory. Lionel did this in the 50's as insulators and to hold wires in place.

@Matt G from VA posted:

My only guess is that it holds the wires away from the headlight bracket but it seems like a bootleg detail on an otherwise beautiful motor. Maybe Lionel needed a quick fix?

I think you nailed it with your first guess.

@Matt G from VA posted:

My only guess is that it holds the wires away from the headlight bracket but it seems like a bootleg detail on an otherwise beautiful motor. Maybe Lionel needed a quick fix?

Yes. It is not a "bootleg" method at all - have you seen all the zip-ties under the hoods of moderns locos to keep things apart/together? There were no "zip-ties" in 1957 or whenever. The paper tape was quite effective.

Lionel never invented twist-ties. Asleep at the switch again!

There just always seems to be some clever little clip that piggy-backs on a a fastener/integral to another piece - or with a little more longevity than tape but I guess I can't expect something as elaborate as the mercury capsule hold downs inside the engine. Also might just be a little bitter about the stains left on the side of the Pullmors :-)

The point made about alleviating strain on the solder connections is very interesting - thanks for the feedback everyone!

I believe that that is a woven fiber glass tape. It is intended for high temperature applications. All the FM s I have worked on have it. Glass tape is still available and I put a new piece of glass tape on to hold things in place. Many of the earlier diesels have a variety of metal clips to restrain the wires. I think the glass tape was a money saving change.