Runaway Legacy Diesel -- Solved

The screw is an allen head screw, and some of the flywheels have two holes, but only one screw.

The common suspects are actually the encoder or the DCDS board I'm sad to say.  I have the Legacy GP7, and it now sports a new DCDS to fix that exact issue.

I've also seen it be the encoder, which is a much cheaper fix.

Some of the flwheels screws are tiny flatheads , I've used a screwdriver from an eyeglass kit to tighten them.

I've had this problem with my legacy gp7 , can't remember which type of screw it had

If you run the loco with that hatch off over the flwheel with the tach reader on it. You should be able to see the flywheel slowdown as the loco speeds up veryfing this is indeed the issue.

The only way to tighten the screw is to remove the shell. When I did mine I remove the screws on the bottom, the raised the long hood up until the plug for the lighting is exposed.

Then  unplug the lighting and you can lift the long hood up and over exposing the motor with the reader. Not much room for fingers to unplug, I believe I used a small screwdriver on one and a fingernail on the other and gently seperated them.

The short hood end has a plug as well, but it can stay connected as your rotating the hood over end.

One of the "other reasons" I'm not a fan of diesels,its always 5lbs of **** in a 3lb bag.

If you want to see this in spades, take apart the Lionel Legacy Lindbergh Atlantic with whistle smoke.  You can't put a dime in there with all the junk that's stuffed into that little boiler!  I'd rather work on most diesels, much easier to deal with.  The GP7 is roomy compared to many steamers.

John and Rick. Thanks and HNY.

Well crap, and I really like that engine. Just looking, after I got the attach screws off my first thought was that this was gonna be worse than my S2 Alco adventure. Will try to isolate the problem better when I get home tonight. I did try rotating the flywheel by hand while holding the truck drive wheels fixed with the other hand and the flywheel can be rotated without the wheels moving. Will also try to run in conventional with speed control off for a visual. Either way I have to rotate that shell up. Will report back with a photo or two.

S

Well, if the flywheel spins without the wheels moving, that's sure a sign the setscrew is loose!

I have an engine that used to take off at full speed for some reason during a run and I set the maximum speed on it and it stopped doing it.  Not as technical as other suggestions, but it worked.  You may want to try that.

Can you use a dental mirror to see if the set screw is there?

A reset is always a good idea when you have issues like this, probably the first thing to try.

I had one that required cleaning.  This was the early Legacy with modular boards.  Dirty and dust on the sensor board.   Though it would initially run fine, then take off.  G

Thought of that earlier but forgot so thanks for the reminder! Will see if they have something like that at the local electronics store. If not, I have to go to the dentist next week and I'll just get one from him!

Catch me if you can!!!

Used a mirror I got at the electronics store. Just like GRJ said there are two holes in the flywheel. Checked each and saw what appears to be a tiny flat head slot looking back at me but hard to be sure. Either way shell has to get out of the way for screwdriver access. Like Rick said, the ONLY way that shell is lifting up and out of the way is to disconnect the lighting plug. Ugh. I sure would like to see a video of factory workers assembling these things. It can't be any easier for them to put it together than it is for us to take it apart.

Back in service! Was able to lift the shell up high enough to maneuver it over the two spots where it was hung up. That gave me access to the flywheel. A flat blade 1.4 mm screw driver fit the set screw and problem solved.

Thanks Rick!

Glad to hear you got it fixed Scott!

Oh yes!! Simple, no $ fixes are the best!!