Kline Tank Loco Mystery

It must be upset that you left it sitting for so long! 😰

Seriously, something has obviously changed. I would give it a lube job and give the underside a good close inspection at the same time, looking for anything out of olace or any obstruction. How are the traction tires? I have the gtw version of that engine and it is a great little runner. Hmmm, actually I have not run it in a while......

Rod

Worst case scenario is that the wheels are suffering from "zinc pest".  Hopefully not, as I have one too.

if it's the front pilot that is jumping the rails, try oiling the axle.

Here are a couple of pix of the GTW tank engine. Nicely detailed and runs on small curves just fine.

Rod

necrails posted:

My Kline CNJ tank loco had been sitting for awhile so I thought I would let it run on the layout a bit while I was doing something else.  This loco previously had been a set and forget item.  Set the speed, get the sound volume right, provide some smoke fluid and let it wander the layout.  Never a problem before.  Yesterday after placing it on the track it decided to hop off the rails at every opportunity.  It no longer navigates a hidden 042 loop (worst spot on the layout for a problem), hopped off the rails on a straight track and seems to be picking the guard rails on my Ross switches.  It looks like the front truck doesn't want to stay on the rails.  There have been no changes to the track, I looked for the obvious already like obstructions on or near the rails and checked for level track.  Other than sitting on the shelf, nothing has been done to the locomotive.  All of my other locos operate fine but to be fair all are diesel except a Weaver 0-6-0.  The little Weaver has no problems.  Thoughts and/or suggestions are welcome?  

Not to be, well, you know - but have you actually turned it over and looked at it? Especially the front truck? You did not say anything about that.

I agree with D500, check everything under the engine even the pickup rolls, sometimes they can move out of position.  Also have you watched it like a hawk on the locations where it derails?

Thanks guys and no I didn't do the obvious and turn it over (duh).  I did look at the roadbed for changes in the track.  Being a basement after all my first thought was shifting due to moisture or settling.  Before you say no way, I did find and eliminate one place where the track moved ever so slightly for reasons unknown.  I did notice the front truck seems to float.  While the entire loco has a nice heft to it, the front truck seems to have a mind of its own.  If I don't see anything out of sorts perhaps adding a small weight there will improve tracking.

Is it possible that the front truck swiveled around in the course of you putting the loco back in its box?  During the MPC-era, Lionel made a 4-4-2 and there was enough free play for the truck to rotate 180 degrees.  In some cases when the truck was turned around there wasn't enough travel to negotiate O27 curves and switches.  FWIW.

Maybe there is something wrong with the spring that pushes the front truck down??

RickM46 posted:

Maybe there is something wrong with the spring that pushes the front truck down??

Good idea, have seen where a derailment will cook the spring on a car or engine and strength is gone.