SOLVED Thanks to all! Looking for help repairing a Lionel 2-4-2 starter engine

What type of pick up rollers does it have ??

Early in MPC production, hollow pick up rollers were tried (and dropped) as they are very sensitive to the slightest bit of dirt or grime on the tracks, not to mention switches.  

If your engine has these hollow rollers you are best to lock it in the forward position.

Ken

do you mean the hollow ones like that are on the older scout engines?

did that, they cant get any cleaner. 

Yes, those are the ones.

If the engine in question has the "snap in rollers", clean them as well as you can, and ensure that they have some spring to them.

Ken    

no they are not hollow, standard rollers that connect to the brass rectangular strip.  Which I cleaned as best I can.  

I might have to just tell the customer that they need to lock in one direction

It happens sometimes, I have a 4-4-2 with the hollow pick ups that runs through anything that I throw at it, yet one of my 4-6-4's with PW style pick ups, that has been serviced, cleaned and them some, I have to lock in forward only.

Ken

Couldn't a capacitor/diode set up be used to help the E-unit coil from dropping out at the cost of holding the direction button longer?

The tech(non train) in me says swap the e-unit with a known good one, or bypass it and watch for motor hesitation or amp fluxuation to eliminate the e-unit as suspect. Coils can be finicky to power changes, fast amp draw could cause a drop out too.

A MARX Commador Vanderbuilt I have did this for years before it suddenly ran right again. All I can think of is maybe I moved the position of some wires during a clean & paint. I suspect they had been shifted over a bit during its one prior cleaning, landing them in a magnetic field area with enough "noise" to have the E-coil drop quickly.

The real pain was it had no direction lock!

the e unit is fine, when I connect using alligator clips directly to the e unit and body frame the engine works fine.  It is only when on rails that the issue happens. 

The rollers must be losing contact with the rails long enough to make the e-unit reverse. Could be the spring isn't strong enough to hold them down.

Since you have already done the cleaning, an overlooked loose wire or bad ground would be my next step.

Jim

Agree with the suggestions of loose wire or poor ground.  How about putting a pickup on the tender truck and supplementing power & ground with a two-conductor tether?  If the loco had the Electronic Mighty Sound of Steam from the factory, it might already have a single connector with supplemental ground on the Tender.

Also dirty brush wells or inadequate brush spring tension can cause this problem.

Finally do all four wheels sit squarely on the rails?  The MPC frames were light gauge compared to their Postwar predecessors.  A fall from the table or a collision could have skewed the frame such that all of the wheels no longer make contact with the track!

My $.02.  -Ted

AS others have said, it is the pick-up roller assemblies. Just replace them, they are inexpensive, about 1.50 each. They just snap in. You can add more tension if needed. Just lift the brass contact near the middle with a small screwdriver near the middle where the dimple is as slide out (after the rollers have been removed) It will come out without having to unsolder any wires. Bend slightly and reinsert. 

I have one (#8203) with the same issue.  Some of these 2-position e-units are just 'jumpy' for lack of a better term.  from what you are describing I don't think cleaning will do it.  I would recheck the grounds--testing it with alligator clips will not necessarily rule out the e-unit.  Also check the e-unit lever and the lug it contacts next to the solenoid.  If that is not clean and tight track vibration can cause a break in the circuit which will trip the reverse unit. 

This is the same engine, I will double check the e unit, the lever is tight.  If the e unit operates fine when powered through alligator clips then isn't it safe to assume it is ok?  I think it is something with the pickup rollers perhaps not making good contact with the brass bar.  I do not see an easy way to pop the pick up assembly off to look closer, I do like the suggestion of adding a pickup roller to the tender

I will try that..

You may want to clean the contacts with a rotary wire brush and use conductive contact cleaner then conductive lube.

After reading this I had a "ohh yeah" and slap in the head moment. I pulled the pick up rollers off, then gently removed the brass tab, bent it down a and replaced all parts.  The rollers were much tighter and no more problem. Thanks for the help.