Quieting down old engines

[whozleft]

I have a couple very old GP units that seem to be running pretty good, but are very loud when they run. Is there anything I can do to get them performing a bit quieter?

thanks for any hints and/or tips.

[James in FL]

If you can figure out what's causing it your half way there.

You don't state the manufacturer so try some of these;
Remove the shell and run the chassis on the track.
Check for slop in the drive train, from the motor shaft throughout the trucks.
Check for worn motor shaft bushings. 
Check for something loose or vibrating.
Check that the motor is tight and properly seated.
Check that everything is aligned properly and that nothing is binding.
Check for proper lubrication.
Check the fit of the shell. The shell may be amplifying the noise.

See if you can isolate the source, and report back.

[whozleft]

Thanks for the tips. They are both Bachmann units.

[James in FL]

Ah, OK then.
Very old B'mann locos are sometimes termed "growlers".
The source of the noise is poor alignment throughout the drive train and/or cracked gears.
Some associate the sound to a coffee grinder.

You used the words "Very old".

So let's say, for the sake of argument, 15+ years old.
At that time B'mann locos were notorious for cracked gears.

This is the stigma, to this day, that haunts Bachmann N scale locos.
It appears to have been addressed.

I have Spectrum locos, both steam and diesel, that do not exhibit this problem. My Spectrum Dash 8-40C's were growlers, my Dash 8-40CW's were not.
All my Spectrum purchases are from 2004 or later.

FWIW I also own the new split frame Steam 0-6-0, 2-6-2, and 4-8-4 versions and they are all quiet and smooth. My earlier versions of these same locos (solid frame - pre '95) all suffered from cracked gears.

Check your gears.

[whozleft]

James,

Yes, at least 15 years old. They seem to run ok, but do growl as you say. I will tear them apart and check the geears as you suggested. I hate to give up on the old stuff since I've had it so long and it has served me well.

I actually looked at a new Bachman engine at the LHS the other day and mey go back to get it this coming weekend.

I really appreciate your help, tips and input.

Take care.

[whozleft]

Since I was on the site I looked up in the parts section and don't see a whole lot of parts listed for engines. Assuming I may have to replace my gears, where do I get them?

Thanks

[Conrail Quality]

Northwest Shortline probably has the gears you need.
http://www.nwsl.com (their site is best viewed with Internet Explorer rather than Firefox; the text shows up transparent for some reason)

Timothy