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I have the 1980 GP #8957 that apparently has an inoperable E unit.  This engine is one that I would run just at Christmas time.  I doubt there are more than a couple of hours of real operating time on it.  When I took the shell off, all wires and contact points are almost factory new.  I can easily move the plunger on the E unit with a small screwdriver up and it will fall down, move the gear and I can manually go thru the position of forward neutral reverse.  The engine does operate in forward and reverse.  The lever on the bottom moves easily and seems to be seated in the correct spot for making contact with the E unit if in the on position.

I have an old repair book that says I should really clean the plunger and gears with TV TUNER or the like, but if the plunger moves easily, is that the necessary fix?  And I’m guessing that when power is applied, the solenoid pulls the plunger up, or am I mistaken?


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The frame of the E unit has to be grounded to the chassis via the mounting screw....even if its tight, it could have lost connection.....loosen the screw, wiggle the the unit just a tiny bit, and re-tighten the’s just a tiny sheet metal screw, make it good and snug, but don’t crank it tight like a cylinder head bolt....that’s the first and easiest thing to check, .....others will have more suggestions.....


Pat: If the plunger falls by gravity without issue, do not do anything!  And yes, the plunger falls by gravity and is lifted by an energized e-unit coil assembly which turns the drum one tooth at a time.

Do not spray anything on the plunger and inner coil if you don't have to. Over many operating hours, the plunger COULD become magnetized, but I never had that happen with any of my Postwar or MPC/LTI items, so I think that is a relatively rare issue you likely will never encounter.

Does your e-unit "buzz" with power applied? If not, I'd check the solder connection on the side of the unit for a cold solder joint; also make sure the other end of the coil wire is also soldered to the frame (doing this from memory...). Some of the soldering I saw come out of MPC was sketchy at best. It should be shiny and nicely contoured, not grainy and dull in appearance.

I’m adding 2 photos. 1 is the E unit.  The other is the shell because I see a little brown spot on it where it sits over the solenoid.

the e unit is screwed in tight to the bracket.  That bracket is riveted to the base.  All interior lights work.

The solenoid wires are soldered to the lugs on each side.  But what is that little black plastic piece at the top of the spool. Is that just from the mold or ?  It corresponds to the brown spot on the inside of the shell.

and I see the 4 wires the green, the red, and 2 blacks come together soldered on the lug to the solenoid.  I black and 1 red go to lights. 1 black must go to the roller. All wires are solidly connected.



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@bmoran4 posted:

That solder joint doesn't look all that great. I can't tell from your picture if there is an e-unit coil lead in that mess.

I blew the picture up, and as best I can tell, it looks the the solenoid coil wire is coming straight out and is tied to the red wire, between the solder lug and where the red insulation starts up. It also looks like a very iffy connection - it's certainly the first place my soldering iron would hit!!!!


Also, if you simply checked to see if the screw holding the e-unit to the bracket was tight, as Pat suggested, that's not really enough. You need to loosen it, wiggle the whole affair (to help break any corrosion) then retighten it.


Ok. Here is what I found when I got a good look with a good LED light.  The copper wire  on the power side lug is not connected to the coil of the solenoid.  If I could take a photo through my magnifying glass, the copper wire looks like it has a dollop of solder at the end where it is not connected. L it may not be anything, but about 1” in from the lug, it is broken away.

what are my options now?

Assuming you pursue this further, and you successfully find the wire end and you are able to unwind one turn as Rob said, you will need to take a sharp knife, or X-Acto knife or a single edge razor blade, and carefully scrape the enamel off the end of the wire before trying to solder it. It is the dark colored varnish they apply to provide insulation.



Ok —stay with me guys.  Here is what I did now.

i found the loose end. I carefully unwind it around the spool till it comes back out to the lug I want to reconnect, where the broken end is at.

as an experiment, I make a splice with the 2 ends, and it seems to try to energize the solenoid.  My splice is not a soldered yet.  I just twisted the wires together.  Just to see if the solenoid will energize.  It does but when it goes to neutral, I can see sparking—- the spool seems to be arcing where the rivet for the e unit lever is , the rivet that the lever rotates on.   But on the inside of the metal case that that holds the spool.

so at least the e unit will work —-when I solder a new connection,—- but trying to not get that arcing on that rivet looks like the next challenge.  I’m pumped that I figured this much out with all the help you guys are giving me.

any thoughts etc?

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