Fixing a Marx 490 O27 toy locomotive

Last Updated on December 2, 2015 by Dave Farquhar

Note: Please don’t do what I did in this post. Chances are you’ll make things worse in the long run.  If you’re looking for information on fixing a Marx train that won’t run, go here for instructions on how to do that.

I fixed my Marx 490 locomotive this weekend. I used the tips in The All Gauge Model Railroading Marx Trains guide. Scroll down to the heading titled, “The Marx motor.”

I was skeptical because these instructions call for WD-40, and it seems I’ve read a hundred other places never to use WD-40 on any model train. But my Marx 490 wasn’t running well, and it would cost more to have it professionally repaired than it’s worth.But before I continue, let me interject something. If you’re here from Google because you just found a box of old trains that say “Mar” on them, the company is Marx, not Mar. And the trains look a lot like Lionel, but they’re not Lionel. In a few rare instances, Marx trains are very valuable. But in most cases, a Marx isn’t worth as much as the box a Lionel came in. Which is why I said it would cost more to repair my Marx than it was worth. I just had two Lionels repaired for $25 each, plus parts. You can usually get a Marx 490 with some cars on eBay for $25.

But that’s not to say Marxes don’t have charm. They certainly do.

There. I feel better now. Back to the story. Where was I? Oh yeah. WD-40. I didn’t use WD-40 on my Marx. I used Gunk Liquid Wrench instead. Two reasons: The main purpose behind WD-40 and similar oils is to clean, rather than lubricate. They leave a little bit of lubricant behind, but not a lot. Gunk Liquid Wrench, like WD-40, is primarily a solvent. But it has synthetic oil in it, whereas WD-40 has kerosene in it. In my mind, this makes Liquid Wrench a better choice for this purpose because what little lubricant it leaves behind when the solvent evaporates will be of higher quality and last longer than WD-40’s lubricant.

But there was a second reason. Liquid Wrench was on sale, so it was cheaper. I also thought long and hard about Marvel Mystery Oil in a spray can–it works in cars and airplanes something wonderful–but opted for Liquid Wrench because the instructions called for a penetrating lubricant, and I didn’t know if the Marvel would exhibit the same kinds of properties. I’m a journalist-turned-computer tech by trade, not a chemist.

But first, I tried omitting the WD-40 step and just cleaned it with Goo Gone and TV tuner cleaner. Like I said, every time I turn around I read somewhere that you shouldn’t go near a model train with WD-40. Between the TV tuner cleaner and the Goo Gone, the train looked brand new very quickly. I was impressed. It ran very nicely too, but the next day it didn’t run at all. Figuring that now I had nothing to lose, I broke out the Liquid Wrench.

After a spraydown with Liquid Wrench, it ran too well–it flew off the track and fell 4 feet to my concrete floor. Ouch. That left a mark. One corner of the cab busted off, and it took me a good 15 minutes to find it. After I’d let the locomotive run 20 minutes–with a big load this time, to slow it down and keep it on the track–I re-glued the broken corner with some Tenax-7R plastic welder. Tenax is great stuff–apply a small amount of it, hold the pieces together for a minute, and they’ll stay. It’ll take 8 hours for the joint to completely dry and reach full strength, but after just a minute, the joint is as strong as it would be with every other glue I’ve ever tried on plastic.

Lesson learned: Keep your test track on the floor. Or surround it with pillows. Or use a Marx transformer that can send just a couple of volts on its lowest setting, so slow actually means slow.

The next day, I ran my 490 the opposite direction on my track–the first time I’d ever run a locomotive that direction on the track. And guess what? I found a bad spot on the track. It derailed–again–and the piece I’d glued fell off in spite of the cushions I’d placed all around my table.

Then I remembered that Tenax is amazing stuff if your two pieces fit snugly, because unlike some glues, Tenax doesn’t fill in the gaps at all. The break must not have been clean enough to give the Tenax adequate surface area to create a very strong bond. So I re-glued with epoxy, since epoxy will fill gaps. It held this time.

So now Marxie has a battle scar and he’s probably worth half what he was worth a week ago, but he runs very well. It’s short on ability but long on heart–it struggles pulling loads that won’t make a Lionel break a sweat. But it’ll pull them, and you can see it working hard doing it. And where a Lionel will just give up on a grade with a curve with a long load of cars, the Marx just keeps spinning its wheels, ever faster, until something manages to catch and it propels on its way.

I think that’s what I like about it. It never gives up.

There are a few other things to like about them too. Like I said before, you can buy a Marx locomotive for less than the price of the box a Lionel locomotive came in. Marxes are easy to take apart–mine’s held together by four joints, easily pried apart with a small slotted screwdriver. And the motor is simpler than a Lionel, so it’s easier to understand. If you want to learn how to fix toy trains, Marxes are easy to learn on, and if you mess up, you ruin a $15 locomotive rather than a $100-$1,000 locomotive.