A buddy gave me an old Athearn GP-38, it has a digitrax decoder installed, wasn’t in the orginal box but does have the parts sheet.
I was warned it wasn’t too good a runner up front, but that’s not quite true. It runs like a champ for about 10 minutes or so (that’s the good news), but then it’ll all of a sudden surge forward and inch or so, the motor making a revving noise, then settle back for about 30 seconds or so, then do it again. This goes on until it finally stops. Put it in reverse and it may run for a little but soon does the same thing.
Here she be on the inside…
First question is about how old would the engine be?
Second, what causes the above stated problem, need a new motor maybe?
Hey there. Well My first suggestion is to unwire the decoder and run the motor with nothing at all. If the motor does the same thing then it is the motor. I suspect it is a decoder issue. Possibly getting too hot or there is something fried in it already. While it is apart check what the current draw of the motor is it may exceed that of the decoder. I had that same issue with an IHC steam engine with a can motor. It pulled more than 2 amps and ran spastic but the motor itself ran great without the decoder.
Also be sure to check your universal couplings where they attach to the metal shafts, if you have one that is cracked it may not be slipping until it gets up to operating temperature, just somehting else to check…
Agree with Forty Niner. That doesn’t sound like a motor problem at all. That sounds like bad gears in the gear towers or a bad universal attachment to the motor shaft. the fact that it’s “revving” is what makes me thing that.
run it with the shell off, when it stalls watch to see if the motor is still spinning but the Flywheels or universals are not.
as for age, its a GP-38-2 which were first made in the 80s. That makes it athearn’s standard Superdrive with the good flat can motor. So the oldest it could be is from the 80s.
You say you can hear the motor turning but the locomotive doesn’t move? In that case either the drive shafts are slipping or there is something wrong in the gear towers. Run it with the shell off and watch. If the motor turns and the U-joints don’t, its a problem with motor shaft slipping in the U-joint. As a rule, if the motor turns, it’s OK.
While you are at it, might as well take the gear towers apart and inspect them. A gear with broken teeth can cause all sorts of trouble. That model Athearn often has bits of nearly invisible black plastic flash inside the gear towers. A careful cleaning, including wiping each tooth of each gear with a pipe cleaner can make them run better.
Jarrell. run it with out the shell and see what happens. All so grab the flywheels and give a twist and see if they are slipping on the motor shaft. That motor looks the same as still being used in the current Athearn RTR engines and they are OK at the best. But still should work with DCC.
If the flywheels slip, pull them and a drop of super glue should do the trick. Depending on how the decoder is hard wired the engine is self is easy to work on.
No, its not that the engine doesn’t move… it DOES move, and quite well for about 10 minutes. THEN I hear a sound like the motor is revving up, the engine surges juuuuust a little, then proceeds on for a little while. BUT, then it will stop altogether. I tried putting it in reverse AFTER the complete stop and it would move in that direction for a while. The revving sound is only for a couple of seconds, then it stops making that sound.
Just as soon as I can get a few minutes with it I’ll take the shell off and watch it for a while.
