How long can I run a modern Lionel engine?

I guess you can run it until it stops!  As for the length of time, that's going to depend on what load it's hauling.  I've run really long consists with various locomotives, but they do tend to work hard and get pretty warm.  OTOH, running 20-30 cars behind the BB you could probably run it all day.

I know @Andy Hummell runs his Polar Express Berkshire a lot during Kennywood Parks Christmas Lights event. Maybe he'll chime in. 

Run it until it blows up. Then cut it up and throw it into the BOF to create future generations of locomotives, automobiles, infrastructure, etc.

Thats what the REAL railroads did and DO. Nick

My trains tend to get their long running times during train shows where something is moving for 10+ hours. Typically I switch out locomotives/trains frequently enough so that no one engine or consist is running over 90 minutes at most. This is pretty conservative though with today's modern motors, you could probably run them for hours and hours without an issue, especially the command locomotives at low speed.

A slight side note, my transformer of choice in train show settings is usually my pair of Lionel CW-80's. They're on continuously for over 10 hours running trains, no issues whatsoever.

I have run engines for 4 hours at Christmas  show for 20 days straight. No problems. Turn them on and let them run. 

I kid my buddies if I sell it I can just say it was test run

As others have said, it's about how fast you run and how much of a load is on the loco. Feel the boiler from time to time. If it gets too hot, swap engines, slow it down, or lighten the load.

The heat goes up linearly with increases in the load, but exponentially with increases in the speed.

If we all recall, Lionel trains ran for hours in store windows and display layouts, back in the day.  But I'm speaking of post-war trains.  

I read, on this forum, I believe, that the Franklin Institute had an "O" scale layout before the HO layout of the late fifties.  If memory serves, the Lionel motors were burning out and being replaced with Marx motors.  Some please correct me if I am wrong.

In considering load, continue vintage of cars. Postwar Lionel is a load.  Modern MTH rolls very easily.

Run 'em 'till the wheels fall off.

Then grease'em up, and run 'em some more! 

Run ‘em until mommy says “For the last time shut that thing off and get to bed”.

Thanks everyone.  It pulls 12, MTH Premier 18" passenger cars from recent years. 

I bought 3 more since this video.  

As a comparison, at our open house today I ran a LionChief+ NW2 at max effort for 6 hours straight pushing hoppers up an 8% grade to our rotary coal tipple.  By max power, I mean I pushed the maximum number of hoppers each time that the engine was capable of pushing up the grade.  

Short version....run 'em all day long.

-Greg

The way I look at it.  Manufacturers make things to use. Not sit.

Only makes them  look good. The longer you use their product.

As long as parts are available .  it's repairable. 

My 736 ran hours up and down a 4x8. Pulling 20 cars. Growing up.  As a kid you don't think of how long to run. 

Same thing for me later .. Still run till whenever.

My 2383 same . the Pittman can motor in my STD berk. Don't even worry about it.  It's run 5 plus hours no problem. 

I run my engines 3 to 4 hours at a time and never have a problem or getting to hot. I just make sure they are well lubed and oiled up!!!

The newer engines with the can motors run for hours w/o getting hot. It's the older PW stuff that gets hot and needs to cool off every 30 minutes or so. As Paul and Jeff said, keep it lubed and you can run it from now to Christmas.

My first-issue (small motor) PE Berk did have a bad habit of smoking the e-board when pulling long trains for prolonged periods. Swapped a board out from WbB and it fixed that problem.  

In the 1970's, the accepted minimum design criteria for locomotive lifespan was 100 hours. (McComas & Tuohy, "Lionel Collector's Guide and History", Volume IV, 1980, p. 19).

My 736 must have over 5. 000 hours. All original. Had to replace the jewels .caused by my crashes.

No one’s mentioned it but you have to factor in smoke unit operation if you run with the smoke on. Basically my VLBB won’t go more than about 20 mins at a stretch with the main stack smoke on before it needs refilling. But I do run mine on the high setting with EFX turned up. When these engines were released, the Mike R. instruction video made it clear that the smoke units in them are very thirsty.

During the post war era, Lionel recommended that you stop and give the motors a chance to cool down about every hour. As others have said, today's can motors have much less current draw and, therefore, less heat than the older open frame motors did. I run my modern engines hours on end without any problems. 

For what it's worth, I ran an MTH bump and go car on an O27 rectangle around my workplace's Christmas tree for 10 hours a day, 5 days a week between Thanksgiving and Christmas.  Went for two years straight with regular oiling before the motor finally called it a day.  In that time, I had to replace the roller pickup once.  I calculated at the time that the little indefinite was running the equivalent of 13 actual miles over one 10 hour shift... 

Mitch 

As long as it's lubricated properly it'll be fine. 

As an example the other day I ran my 1996 vintage Lionel Santa Fe F3 the other day pulling a dummy F3B with Railsounds 2.5, a dummy F3B, a Dummy F3A, and eight 16" aluminum passenger cars. After about an hour and fifteen minutes I noticed that the headlamp had gone out. I popped the shell off to change the bulb and decided to see how warm the Pullmor motors were. Both were only a degree or two warmer than my hands, so maybe 100°. I've run that same locomotive/train for 2-3 hours without issue. The shell/trucks are never much warmer than human body temperature (remember you only really feel warmth if the object is over your body temperature). The only thing that gets noticeably warm is the fuel tank area, where the LCRU sits. I've run my big MTH Premier Santa Fe 2-10-4 Texas with a 9434 Pittman motor for 2-3 hours pulling a 20 car freight train at 45 scale MPH. Not noticeable heat build up.

So OP running a Legacy Big Boy for 3-4 hours pulling a 20-30 car train isn't going to hurt anything.