My HO SD40-2 (Indiana Rail Road) makes a odd clicking and humming noise after sitting dormant for a few days. What is the problem and how do I fix it.
Try to isolate the sound. Is it coming from the front or the back? Is it coming from one of the trucks or from the motor?
Well, for one thing, you didn’t say that you had taken the shell off and were at a loss as to what was happening. All you did was throw up your hands and ask for help without telling the rest of us anything about any troubleshooting procedure you went through, if any. You can’t fix things when you don’t know what’s causing the problem. Besides taking off the shell what did you do? I mean, what exactly did you do to try and figure out what was causing the problem?
Have you taken the time to figure out how the mechanism works? Once you’ve done that, it narrows down the problem areas.
As for a clicking noise, my guess (and that’s all it is) is that some rotating part is intermittently hitting some non-rotating part. Without the engine in hand to diagnose the problem, that’s the best I can do.
-Andre
[edited by selector]
While you have the shell off, lubricate every moving part, including the motor bearings, drive shafts, and gears, with light machine oil. If you don’t have some hobby oil in a special dispenser, you can use the tip of a toothpick to apply small amounts of oil.
I have found Dexron III automatic transmission fluid to be an excellent lubricant for models. It is made to withstand extremes of temperature without running off or hardening, it is plastic compatible, and is cheaper than hobby oils.
Slowly run the engine with the shell off and watch to make sure nothing is rubbing on the drive shafts, especially as it goes around a curve.
A clicking or thumping noise in some of the early Proto 2000 locomotives was a sign of cracked drive gears in the trucks, but Athearn was hardly ever known to suffer from this problem. In fact, Athearn gears were used to replace P2K gears in many cases.
Right you are that it doesn’t happen to Athearn’s often, but as with everything else there are exceptions. I’ve had three Athearn’s with cracked gears. An F7 that had two, one in each truck, an SD40-2 that had one in the rear truck and an SD9 that had 5, three in the rear truck and two in the front truck. All of the locos had sat up for a long time and I’m guessing that over time the plastic shrank enough that it cracked. I replaced the axle gears in all of them and they run normally. It’s quite possible that part (or all) of your problem could be due to a cracked gear(s). Other loco brands I’ve had this problem with are Proto 2000, Walther’s and AHM.
All of the above posts offer good advice except for the part where the OP says that the sounds occur after the unit has sat dormant for a few days. I take it to mean that the noises go away after the unit has been running for awhile, but then come back after the unit sits for a week. Any noises involving lack of lubrication or cracked gears would, I believe, be pretty constant.
By the way, which Athearn SD40-2 mechanism is involved here: the original drive with all the universal joints, the first revision blue box with the hex drive, or the newest RTR with the hex drive and DCC sockets?