Lionel MPC reverse units

[Anonymous]

I have recently been experimenting with improving the performance of a MPC GP-20 myself. It has an old style electro-mechanical E-unit and the integral motor/truck. When the E-unit is ON it has a loud buzzzzzzzzzz (60Hz AC) so I installed a bridge rectifier t run the E-unit in DC. After installing the rectifier with no other electronic components the E-unit then buzzzzzzzed at 120Hz. So I put a capacitor across the + and – outputs of the rectifier. This stopped the buzzzzzzzz but sadly the E-unit ran very HOT, TOO HOT, in DC, so I wired the E-nit back to AC operation were it runs much cooler. I next turned to the motor/truck; you can pull down an illustrated parts breakdown IPB from Lionel’s web site for your particular engine. There are three things you can do to improve the performance of Lionel’s open frame motors. One, once the engine is apart, clean or replace the motor brushes. Two, clear all the gunk out of the gearbox and the motor worm gear, then lube the gearbox and worm gear with a good quality gearbox lube used be RC racecar hobbyists, I use a silicon based lube compatible with plastic and metal gears. Three, reassemble the motor/truck, many of the open frame motors have a thrust bearing / Allen screw that can be used to adjust the backlash of the comuntator (sp) w/worm gear once it is mated to the gearbox. Slowly tighten (or loosen) the thrust bearing until comuntaror (sp) still spins freely but the up and down movement is minimum. It was after TUNING the motor truck my MPC GP-20 ran very smooth with little gear noise (growling), E-unit buzzzzzz aside. Hope these suggestions help.

[eZAK]

choochin3,

Have you run the engine more than 20 min. with the E-unit in by pass?

It could be that the motor is heating up.

If you are shure it is the E-unit I would swap it out with a electronic one.

[choochin3]

I can see that the Eunit coil is energizing and moving freely and the contacts are moving into place with every cycle. I have never operated this loco on DC power but I purchased this engine used .Do you think it has bad contacts ?Thanx brianelO27 for your help!!!!

[brianel027]

Choochin, you're not using DC current to the track are you? DC current can cause the older electromechanical e-units to act sluggishly and sticky, as the DC current tends to magnetize the coil more. I do use DC current (I can go to AC also) and I do notice that the mechanical e-units are more slugglish with less "snap" on DC current. But I've never had any problem with them not working at all after running them for a while.

You'll probably want to pull the loco shell off and see how freely the e-unit barrel moves. You'll want to keep the engine unit rightside up and apply some current and see if the e-unit parts move freely and snap into place. Some electronic tuner spray may be all that you need. You spray the contacts and the inside of the coil of the e-unit with the spray.

It is possible that if your loco is a diesel and was purchased used, that the mounting could have been bent alittle... I had this happen once. By using some needle nose pliers I carefully bent the sheet metal mounting (cut out of the loco frame) forward to get the e-unit more level.

Also check to be sure all wire / solder connections are good and not loose.

It's also possible the unit itself may need some minor adjustments or tweeking. But if you've never worked on one before, I'd consult with someone who has. Or get yourself a copy of the Greenberg Repair Guide. Classic Toys Trains has done at least one article in the past 15 years on mechanical e-unit repair... I just checked - there's an article on e-unit repair in the June 1991 issue of CTT. It's a 5-page article. If you can't find the issue somewhere (maybe the editorial gang at CTT can assist) I could copy the article for you if you can cover the costs and the postage (money is real tight for me right now).

[choochin3]

I own a older MPC steam loco with a 2 position reverse.This loco runs well for about 15-20 mins.then it stalls.It acts as though it went into neutral with the headlight on.I know this e unit has no neutral position. But it refuses to move.Does anyone have any info on tuning up or repairing these goofy E units?Any help will be appreciated!!!!Thanx