Metallic sound

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#1
Just out of curiosity, I have a PH4 that has been rock solid for about three years now. I have literally flown it all over the world without a hitch. So, after about 20 hours total flight time I am starting to hear a whining metallic sound when flying. I don’t see any issues in response so far, but am a bit concerned. Is there any maintenance I should be doing on the engines? Any issues I should consider as I add flight time to these engines. Would appreciate any advice.
 
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#2
More info needed. With the props on, spin the motors with one finger slowly. Do they all feel the same? Also try to move the prop in a horizontal direction. If you have a bearing failing, you may get some sideways play, but very slight. If it is a bearing, I would not send it up in the air.
 
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#3
A quick check of bearing health is post-flight motor temp. This can be performed with your fingers.

It’s unlikely you’d have four failing bearnings so just do a quick check. If they are all similar it’s not likely bearings.

This sound has been reported occasionally over the years with all variants of Phantoms. Don’t recall any connection with a pending failure.
 
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#5
Thanks all.

Starz: with props on, they all feel the same (i.e. no scraping or metal on metal rubbing feel). Each gives a small amount of horizontal play, when holding the prop, not when holding the engine itself. So, I am assuming that is flexibility in the prop mount more so then a sign of a failing bearing. Also, given all four have the same amount play, I am hoping that’s a good sign....

N017RW: Each engine gets warm, but not really hot to the touch. If there was an issue, I am guessing I would have an engine noticeably hotter then the others. Is that correct?

I did get an odd message in flight , it was “battery power limit will automatically reduce the aircraft’s mobility to insure flight safety”. May have nothing to do with it, I was at about 30% battery and bringing the Phantom back down to land when I noted the message. I have not seen this particular alert in the past.
 
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#8
AND its been advised here as i have read it in many threads and from people who are very knowledgeable : that Its BEST Not to run engines Up to "FULL SPEED" with no props !...the speeds them engines will go to is not good for them and the tiny itsey bitsey ball bearings will sure suffer !

Just wondering has that drone in its life time......maybe been "left out in the rain" and water got in all the motors bearings ?
OR been took off in a very very dusty area a whole lots ?
well its a few idea and i wanted to ask them.
 
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#9
Hi Motor, I have never run the engines without props. Had assumed that would not be a good idea.

I have flown in a multitude of conditions, from beach sand to snow to trail dust. Never in rain or overly wet conditions, but I have flown very close to both fresh and salt water features many times. Never had any issues, but then I have always been careful to get close to water, but not close enough to get the engines wet.

I have sprayed out the dust with an air can, but the engines don’t look noticeably dirty. I normally see dirt/dust around the gimbal, not the engines. If the engines were getting dirt or grit in them, other then an air can, how would you clean them?
 
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#10
Sometimes....that high pressure out of the "canned air" can actuality do more "bad then good"....By blowing so hard that tiny dust particles are blown in the cracks of the bearings !..they are not sealed like automotive bearings are.....I'm very sure i will hear different that some ones done that for years AND NEVER HAD A PROBLEM.. But who knows maybe they have and not shared it...I don't think dust on a motor would not do any harm "The Motors"... its best to wipe them off and fly On >>>>

And please never ever TRY to oil them !....i have seen many threads here and its a No No !
 
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#11
Part of this topic was covered in a thread i started awhile ago about running the motors without props on. Yes you can run them without props and its actually a good way to check for bearing noise. Their rpm is precisely controlled by the ESC regardless of load and they cannot over rev. That being said I dont recommend running them very fast anyway and there's no need to. If you have a bearing problem you'll hear it even at idle.
Operating motors with no propellers
 
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#12
AT low rpms and No props....How about the old method of a foot long stick to the plastic area right around the motor while at a low speed and other end of the stick to the ear " But not inside "... like US older mechanics did to find a bad lifter or a alternator bearing ect..and see if the sound is like a grinder or s m o o t h at lower rpm's ONLY and see IF all others sound the same.
 
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#16
There have been issues in the past with worn prop mounts resulting in a grinding noise. Do you have the updated P4 series prop mounts or the originals? The updated mounts came stock on the P4 Pro, and a single coil spring on the center post replaces the metal plate with three wing-tabs that came with the original P4. If you have the original mounts, lift up each wing-tab to bend it back upward and consider upgrading to the newer version. Also, replace all the props as mentioned by Nightwolf above.
 
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#17
I do have the originals props, and a new set. I don’t hear any difference between them. So far, I haven’t had any issues beyond the sound. Thanks all of you for your suggestions. I will post an update if something changes. Hopefully not.......
 

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