C420 MRC/Lima noise

[LehighValleypa1]

First post in this forum, hello to all.

I have two 15-20 year old MRC/Lima c420s and both have developed a "thumping" noise. The first unit ends up having broken spur gears and has been converted to a dummy. It still has some of the noise.

I purchased another used unit and it came with the "thumping noise" also. I disassembled the thing , cleaned and checked everything, re-oiled and the noise is still there. All of the gears are good, the wheel sets cleaned and no flat spots that I could detect, and the truck pick up wires are in the proper place. The only thing I didn't check was the gear at the end of the drive shaft at the top of the truck housing, can't figure out how to remove the top.

I put DCC in the newer unit and except for the thumping it runs beautifully. And I forgot, it makes the noise at all speeds. Hope to hear from someone with the same situation. Thanks

Steve

 

[LehighValleypa1]

and

The units are HO scale.....Steve

 

[Cjcrescent]

Still sounds like a cracked gear. Probably one of the idlers. You need to totally disassemble the trucks to check all the gears, even the worm on top of the gear towers.

 

[NH Mike]

Steve I've regeared my C420 Lima because of broken axle gears. NWSL #77610 are brass and the number of teeth and the pitch diameter are correct. The hole is a bit small and will need to be carefully opened up to fit the Lima axles. A NWSL puller is best for doing the gear swaps. My idler gears and shaft gears were fine. When the job was done the engine ran as smooth and quiet as any of my Kato or Atlas engines. Yours may have another problem causing the noise but in the dummy it has to be one or more wheels not running true. Is the motor still being powered even though it no longer is driving the wheels? Maybe that is where the noise is coming from in that engine?

 

[LehighValleypa1]

C420

Hi Mike:

I completely disassembled, cleaned, checked, and re-assembled the unit and the noise is still there. Since my post I've re-checked and the dummy does not have the issue. All the running gear is out of the dummy.

The powered unit now only makes the noise while going up a grade and it sounds like something slips and then the noise. At your suggestion I'm going to order new wheel/gear sets from NWSL. Maybe the axle gears are worn and that is causing the slipping. Thanks for your help.

Steve

 

[NH Mike]

Steve last time I checked NWSL does not make a specific set of axle gears for the Lima / MRC engine so you'll have to order them by the part number for their universal gear, #77610. Four is all you need but in my case I ordered 6 just in case one or 2 got messed up while reaming out the holes. Your noise could be excess back and forth play in the motor or drive shafts. Does it make the noise going up hill both backwards and forwards, or just when running only in one direction? Good luck with the repair. These really are a decent little engine if you don't need the latest and the greatest in add on details.

 

[Icheymon]

Steve, I picked up one on vacation and was dismayed to find the same problem. I contacted North West Shortline Customer Service and they advised me to purchase #2554-6 Lima 10T 40"/110 Geared Wheelset - Premium Nickel Silver. The package arrived today, I installed the wheel and gear sets per their instructions and the unit runs silent. With shipping was 30 bucks.....more than worth it to me.