Is it OK to replace only one motor on a twin motor loco?

[Ralphmp]

I have a Mallet where the front motor block has the "hesitant start" lurgi - doesn't want to turn at first but after a few seconds grudgingly comes to life, then runs fine for the entire running session and then exhibits the same hesitation next time it's put out on the track.

I've cleaned up the motor block (a previous owner appears to have used a car grease gun to lubricate the gears so there was grease everywhere - yuk!) and fitted new brushes and this has improved things a bit but the problem is still there. I've also checked and rechecked the quartering is ok and, despite the loco only drawing 0.5 amps when running round the layout with a couple of coaches attached, I'm coming to the conclusion that it's the motor that's poorly.

I'm really not up to refurbishing the motor so for peace of mind I'm thinking of fitting a new one. However I'm not sure if this will promptly put unwanted strain on the existing motor that's currently working fine. "Logic" would seem to say it's best to replace both motors at the same time, but before I go ahead I wondered what other folks' views / experiences are on this.

Any comments would be much appreciated.

Thanks

 

[Zerogee]

I realise it's largely down to cost - but personally I would replace both motors so you're sure, and then put the one removed "good" one into the spares box in case you need a used replacement later for a single-motor loco.

Jon.

 

[Gizzy]

I've replaced one faulty motor in a V51, with no issues Phil.

I can see the merit in changing both and keeping the good one as a spare though as Jon suggests?

Is the inside of the motor gunked up? My V51 (brought 2nd hand) had been over greased, and this was why the motor failed....

 

[PhilP]

Please be aware that new stock Buhler motors (with the same part number!) are now different to the older motors..
They are more efficient, so will start at a different voltage (probably) and rotate at a different speed for a given input voltage.

Therefore, I would replace BOTH motors, and keep the good 'older' one as a spare..

But before you do this, have a very good look at the intermediate idler gear s in the block.. If the face of the gear which is driven by the worm on the motor has gone concave, then this could well be your problem.

 

[Ralphmp]

Thanks for the responses.
Jon - this is what I'm thinking, also I think it better to shell out for the second motor rather than wait and see and maybe end up spending more in the future should the current good motor play up.
Gizzy - good to know and yes, the motor was covered in grease; horrible!
Phil - thanks for the info on the new motors - very helpful - and also the suggestion on another possible cause of the problem. Another evening with me, the Mallet and my toolkit!