The Big boy engine has a broken rod. I don't know what to call it, but it is between the points A and B on the attached photo. Rod C is one of the pivot rods on the front truck, just below that is a rod that connects from under the cow catcher to the bottom of the boiler. If you notice a white spot at the end of arrowhead B, that is where its broken. There should be some piece that goes from there and fits into the boiler, a clip maybe?

So going to check Mizells, or directly back to the Big L.

Purpose of this post is to share with others, to watch for a weak connecting rod.

I have one curve where it goes clunk but does not derail. I better check and correct the track work before I have your issue. Update: two popsical sticks under the straight track before the curve worked.

This message has been edited. Last edited by: winrose46,

Winrose,
Notice those scratch marks near the A arrowhead. New otta the box, when this engine would take a curve left or right, the boiler we skip just a little bit when passing over the pivot rods. I thought it was normal, then about 3 weeks ago found another person with the same engine and his did NOT have that little skip.

Mine has the same marks; however, by raising the straight going into the curve by the thickness of a popsical stick has stopped the binding. I just ignored it for 6 months and thanks to your post I got the initiative to investigate and correct the track work. I will find the time to look at your arrow B on mine to see if there is clip or other retaining device.

Don...that's the steam exhaust pipe that goes to the smokebox. This was causing me grief on my layout, as the loco would derail intermittently on a 072 crossover. I finally found out that this was the culprit and did some modifications to it. It seems there should be a tension spring attached to the backside of this that attaches to either the underside of the smokebox or front engine. It is still a mystery...

Albert, Located UNDER the pivot rods and connects to the concave opening at the bottom of the boiler, right?

I'm sending mine off to Lionel today. Hopefully will see it back soon.

Don..the steam exhaust pipe is what you have labeled "A" and "B" it has a vertical piece that extends up into the smokebox(yours has snapped off as indicated by your photo). Pipe "C" is one of 2 steam delivery pipes which pivot when the front engine enters a curve.
The steam exhaust pipe(A/B)should always run parallel between the two steam supply pipes(C),not crossed over as shown in the photo. This will cause derailments as it is not centred at all times.

Albert, I sure like your explanation, that means alot. The photography is not very good, but if you look real close in the picture. I believe the 2 steam pipes you are describing, you will be able to see the vertical section of the right one. The left one is the one I labeled. But your explanation sure makes sense! The engine is one its way back to Lionel.

Thanks for your insight.