hello,
I was wondering if anyone out there can advise when/how I would know when the motors need replacing (such as hours flying in use) as I want to avoid an in-flight failure!

You'll probably upgrade to a new Phantom before your motors wear out. I've never seen specific numbers on the lifespan -- but, also have never seen anyone mention they had to be replaced due to wear and tear.

Good question.  I have that too.  I have seen a number of videos that talk about measuring vibration and others that have a digital tach.  I am not sure any of these would work on the Phantom.

As you power up the Phantom and then do the CSC to start the Phantom motors, it is a good idea to watch the props spin up and if one of them seems to have any latency or hard start so to speak I would think is about as much as you could hope to see.
It would be nice if in the Phantom Assistant there was a current meter or something that would allow you to monitor the four motors while running (props off of course)

Northofthe49th, that latency and/or other speed related issues are usually caused by bad ESCs. But, sure, it could be related to the motors too.

Does a motor heat up more than the others if the bearings are going out?  I was thinking about checking the motors for heat buildup after a flight from time to time?

oakspi Posted at 2015-3-14 01:02
Does a motor heat up more than the others if the bearings are going out?  I was thinking about check ...

You should do that after every flight, part of the post flight routine.

Gerry1124 Posted at 2015-3-14 01:04
You should do that after every flight, part of the post flight routine.

Thanks again, Gerry

WOW This is good chance for someone to write a simple program to test motors and ESCs.  {:3_48:}  

mike@singerscre Posted at 2015-3-14 00:59
Northofthe49th, that latency and/or other speed related issues are usually caused by bad ESCs. But,  ...

Especially if you are taking off from dusty ground or sand etc. none of that is good for the motors and in that case nothing to do with the ESC unless the ESC over works to try to run the motor then you could have multiple problems...

Thanks guys...so, basically, there is no way to check other than 'keep an eye on it'...

deanadamedge@me Posted at 2015-3-15 05:50
Thanks guys...so, basically, there is no way to check other than 'keep an eye on it'...

Pretty much visual, noticing any extreme heat under the motor, listening if something sounds vastly different from last flight to next or on landing. I will often just spin the prop one quarter or half a revolution just to make sure they feel the same, that is about it.

OK...many thanks...

I carry a can of compressed air and use it on the motors often, especially when flying in or over sand.  Suggest the same.  Will open her up at least monthly and spray out the insides and do a full inspection.  If flying in dust or sand will inspect more often.  Any landing in sand needs a full can of compressed air before flying again.