Cleaning dried grease from gears

[Tom4884]

I have an older Con-Cor Big Boy that has been in storage for years and I took it out to run and it just buzzes. Took the shell off, and removed the motor, tested it and it works fine, but noticed lots of caked, dried grease on the gears. I can get some of it with various tools, but was thinking about dropping the whole mechanism, without the motor of course, into an ultrasonic cleaner with some distilled water and some Dawn dish soap. Anyone tried this before? I am really hesitant about taking the gear towers apart because of trying to re-quarter the drivers. Any thoughts?

Thanks, Tom

[peteski]

I doubt water and detergent will be able to dissolve that crud.  My favorite degreaset for N scale mechanisms is Naphtha.  Can be purchased either in Ronsonol lighter fluid, or more affordably as VM&P Naphtha in quart or gallon cans in hardware stores.

99% (or in a pinch 91%) Isopropyl Alocohol is also a decent solvent, but not as good as Naphtha.

I never use water (tap or other) for cleaning N scale mechanisms (but I do use for cleaning the shells).  No need for distiller water.  We are not talking about highly precision laboratory equipment.

I think on that loco I believe you can hold  the chassis upside down and remove the bottom gear cover, exposing the gears (without the wheelsets falling out. You can take an old toothbrush moistened with Naphtha, and loosen the dried grease.  Wear rubber or vinyl gloves because Naphtha will dry out your skin.

Also those  Rivarossi "can" motors with weak soft-vinyl magnet don't have much torque (read "they are rather crappy").

[mmagliaro]

Agree with Peteski.  Naphtha, 99% or 91% alcohol, either will work.   Soap and water will not.  You need a solvent that is higher up the "food chain". 

What makes this an especially nasty job is that even with a good solvent and a toothbrush, you will wash out "most" of that white crud, and what's left will re-harden as a coating on all the parts.  So expect to do many rinses until it's really all gone.  I have been through this exercise with that very engine and the Challenger.
If you think you mostly got rid of it, but some remains, the engine will run for a little while until the grease rehardens somewhere.  Sometimes there are sections of that grease that get rock hard so you need to let the solvent soak on it for a while just to turn it to "goo"so you can get it out.  In my case, I disassembled the whole darn engine down to the frames, drivers, gears, etc.

If you're not going to go that far, exposing the gearboxes as Peteski suggested is a must.  You have to get all white crud out of the gears or the problem will never go away.  Just be careful not to move the drivers while you have the covers off, so you don't upset the rod quartering.  Even if you do, the drivers are all gear driven and the rod slop is pretty forgiving on those engines, so if you take some close photos before you start, you should be able to get the drivers back into the correct orientations if you accidentally dislodge them.

[Zack L-J]

Is naphtha plastic safe? What about paint? I’ve got some old diesels that need cleaning up, and I just want to know how anal I have to be about cleanliness.

[peteski]

Is naphtha plastic safe? What about paint? I’ve got some old diesels that need cleaning up, and I just want to know how anal I have to be about cleanliness.

Naphtha and alcohol are both mild solvents.  But alcohol is a polar solvent, so it is  not as good as naphtha for dissolving petroleum products (grease).
Mechanisms are usually not painted, so I would not worry about it.  Even if the some of the mechanism (like the frame) was painted, a brief contact with Naphtha would not affect the paint.  If the metal is darkened, that is usually not paint, but chemical blackener. But like I mentioned earlier, I would not use alcohol or naphtha (just dishwashgin detergent and warm water) on body shells (which are painted).