Known problem.

Has been discussed here before, mine did the same unfortunately.

But the clicking sound is normal IMHO, they all do it.
You may not have heard it before because the sound is simply deafening with this model!

But the "non-start in reverse" issue has to do with sticky brushes .

For some reason the brushes on these motors do not receive enough pressure from the little bronze springs, so that the least amount of contamination in the brush holder (carbon residue +oil) prevent the brush to come back to the commutator.
That it happened some time after you oiled it is a telltale sign.

You'll need to clean it once again, with lighter fluid (once again, my fav trick..) including the inside of the brush holder.

Then try to slightly increase the pressure on the springs by slightly bending them.

Repeat the treatment on the other side...because it will happen there too soon or later!

In addition I replaced the brushes, because I suspect the original were probably part of a lower grade lot. (otherwise, how would one explain it happen with just **this** one? )

Good luck

Jacques

do not forget to clean the inside of the little square tubes that hold the brushes. This is where they get stuck

Glad it turned out OK for you.
Bad brushes, definitely.
Look for teh ones with a bronze hue in it.
Pure carbon (grey) is sh.t.
What good would be in all the years+countless hours of working on Märklin trains if it's not to share it with you all?

AFAIK there is only one reference.
Just don't know whether Märklin has only one supplier, and coherent quality.
It just seems to me that there are variations in the material . Some will wear out very slow, creating little dust, others will literally break apart.
The old ones last forever...
I reckon it's annoying...but as long as you know how to get around the problem, we'll just have to live with it.
Cheers
Jacques

Maybe a possibility, but not in plastic: the bronze spring is a big part of the electrical contact.
Now, higher pressure won't help if the brushes are made of "chocolate" carbon ...it will just make them break off faster. .
For the moment, I just replace them.

From reading this thread about the carbon brushes, I come to the conclusion that Marklin at some stage decided to buy cheaper brushes, as you all say the old brushes were better. I beginning to believe that Marklin is hell bent on trying to destroy the "Marklin" name and if they continue with these "cost saving" exercises, they will certainly succeed and I don't want this to happen. Can someone please tell the Marklin management to wake up.

Me too- no bitching here. Märklin is what it is and I for one am happy that they still exist.

But I do have a related motor issue that sheds more light on this problem, which as you suggested Jacques appears more widespread than just one model.

Two weeks ago I bought a 26495 Montreal Limited train set. It was about 5 years old but still brand new in the original packaging. The ALCO PA-1s (PA-4s actually) are beautiful and I remain committed to the super robust and easily updated DCM powered locos. No bitching, honestly.

However, I now have had a problem with it as well and it may be related to my VT 11.5's issue. I have always believed that some reverse running is good for a motor, particularly when it is new. So after running those locos for about a week I swapped ends and ran them backward for about 4 days. Then I returned them to the factory orientation to run them some more in the proper direction. But after about 10 minutes I noticed that the train had slowed down a lot and I shut everything down to investigate. Turns out that the rear DCM was still running strong - strong enough to skid that beast of a front loco along on its stalled traction tires! That loco had power but no motive power at all.

So I opened both of them up and I found a lot more gunk inside the brush plates than expected for just 5-6 hours of running. The brushes looked fine but I did not verify that they were free to move. I removed both brush plates and cleaned everything, checked the fit on the brushes and reassembled the motors. The commutators were pretty nasty, with no visible copper on the contact area left at all, but just black buildup. I cleaned them as well before reassembly. Now it is all working perfectly again.

So two things are in common between the VT 11.5 and the PAs beyond both having double DCM power units. Both models are extremely heavy, with the weight everywhere in the all cast construction VT 11.5. The PAs are nearly solid blocks of metal and weight a lot on their own - about as much as my Big Boy! So those DCMs are pushing a lot of metal in both cases and maybe even those torquey motors can't handle that much load. The other thing that they have in common is that I ran them in reverse and then shortly after going back to normal running, one of them stopped. I run the VT 11.5 in whatever direction fits on my track, so it may easily be running in the reverse direction at any time. I ran the PAs in reverse purposely to "break" them in. So maybe that backward running does not bed in these brushes but rather tears the hell out of them and screws up the motor.

They are both rotating off of my layout anyway and they are both running perfectly as I pack them up. It will be interesting to see how they behave when I get them out next time and I am going to try to avoid running them backward. My 19 year old California Zephyr still runs perfectly with just one change of brushes in all of that time. Because of its A-B-B layout it is hardly ever run in reverse, but in addition, it does not weigh anywhere near what the ALCOs do.

I would be interested in hearing if anyone has had similar DCM issues and can see any pattern in this stuff. I only have those three double DCM trains for comparison and that is too small of a sample. My single DCM powered locos all run perfectly with only occasional, basic service. I will continue to use and love them as always but I will be keeping a much closer eye on them in the future. I never assumed that would be needed with such a normally robust and basic motor as the DCM, but apparently I was wrong.

Cheers.

Wow - what a nice collection - Thanks for the input! That is definitely a better indication of potential problems than just my small sample. It seems that luck has not been with me!

Good to know that this problem might not be widespread, since mine are some of my favorite models.

Maybe this is just a batch of bad brushes in the trains that I have bought - the luck of the draw as we say. I do know that my older DCM models have been very reliable over the years and required almost no care or feeding. There really is not anything different about these motors otherwise, so bad brushes make sense to me.

Time will tell how mine do in the future and I do intend to replace the brushes when I get the chance to run them again. I also intend to run them less in the reverse direction in case that is part of the problem.

I will enjoy these beautiful locos and I will keep an eye on the amount of oil. The person I bought it from oiled them and tested them before sending them to me. When I took the brush plate off there was more oil inside than I expected, so that may have been the problem. I wish Märklin had stuck with the bearings for these motors, which would make them much nicer.

Thanks for the advice.

Good advice Chuck, and that is on my todo list.

I have read about people doing that upgrade but I don't have a drill press and I am afraid that I would not get the hole in the brush plate exactly centered if I just use a hand drill. I can't imagine that the motors run very well unless the bearings line up perfectly.

How did you drill the hole in your brush plate? Does the one in the metal casting just replace the plastic insert that Märklin puts in when they make them? I have also not been sure where to buy the sealed type bearings. If I did that I do think it would eliminate the brush breakdown problem which does seem to be caused by too much oil. I will have to speak to my lazy, grouchy shop foreman and see if I can get some of mine done too.

After I worked on mine this year I decided to have spare brush plate/armatueur sets on hand for them. I have older dcm locos which have never had a moments problems so I am at a loss to understand why these are so delicate.

I still love them and I will still run them however fits - that after all is the point of a double ended train set like that. I will just know to keep a close watch on them. I also want to try a ball bearing upgrade on one of them to see how that goes. I oil these just like I have oiled dcm locos for 30 years and the newer ones are the only ones I have seen get so wasted in just a few hours, rather than a few years of use.

This will always be a favorite train of mine though - I just need to figure out how to live with it - kind like the wife.

Interesting information about just how heavy this train really is Ross. Thanks for the insights.

I don't believe that ball bearings would improve the performance of these motors, but I still wonder if oil in the motors is contributing to the breakdown of the brushes. If that is the case then the ball bearings would help. That was a good comparison between the performance of 37605 and 37607 on grades, and provides more insight into the limited pulling capacity of these locos.

These dcm units represent extremely old technology and maybe in these heavy models they have finally met their match. I have seen how they can be replaced with modern motors but it is a pretty drastic action involving irreversible changes to the power trucks. My current plan is to run and enjoy my dcm locos and to keep a closer eye on their status and to have some spare brush shields, brushes and stators on hand. In time I could become brave enough to replace the motors in the heaviest locos but for now I will just wait and see how it goes.

Cheers!