Fluval FX5 motor is knocking

[waytoodeep03]

I am having a knocking noise on my fx5. I cleaned out the motor and the impeller. Impeller looks good so I put some silicon grease on it to hopefully make it turn smoother.

I turned on the filter and it sounded quiet for about 5 minutes then the knocking started again. Sounds like a clicking/rattling type of noise.

I also have an fx4 and fx6 and those are as quiet as a mouse.

Has anyone faced this issue before? If so how did you fix it?

 

[deeda]

Is it possible you didn't put the gasket in the correct spot? Or maybe the impeller shaft broke? I'd take it back apart again to check.

 

[waytoodeep03]

Is it possible you didn't put the gasket in the correct spot? Or maybe the impeller shaft broke? I'd take it back apart again to check.

Yea it was knocking before I took it apart. I went in to see if sand got in it. Im thinking maybe the motor is getting weak?

Id hate to buy a new motor as they cost almost as much as the filter used

 

[iridescence]

try unplugging it, wait for a few seconds to let the air out, and plug it back in.

 

[waytoodeep03]

I am having a knocking noise on my fx5. I cleaned out the motor and the impeller. Impeller looks good so I put some silicon grease on it to hopefully make it turn smoother.

I turned on the filter and it sounded quiet for about 5 minutes then the knocking started again. Sounds like a clicking/rattling type of noise.

I also have an fx4 and fx6 and those are as quiet as a mouse.

Has anyone faced this issue before? If so how did you fix it?

Here is a video of the exact same noise that I am experiencing.

Filter is clean. Impeller is clean

 

[Oscar Mike]

Here is a video of the exact same noise that I am experiencing.

Filter is clean. Impeller is clean

Sounds like there's either sand stuck somewhere or the impeller shaft broke. I haven't fully taken apart my recently purchased fx5 yet but was able to fix a Chinese canister impeller using a nut cracker set lol. One of the picks was almost the same diameter as the impeller shaft so I sanded it smooth and cut to size. Works like new but sounded just like yours before because the rubber stoppers were holding both halfs of the shaft making the magnet wobbly.

 

[duanes]

To me that sounds like cavitation.
Which could be from a number of various issues.
If the impeller shaft is slightly out of line, from something as minor as a grain of sand that got caught, and slightly wore away some plastic, causing wobble, this wobble can cause cavitation.
Cavitation happens if something is out of line, and bubbles are actually separated/pulled out of the water and collapse in the impeller section, doing damage.
Below is a link of cavitation on a very large pump
PreviewPreview4:00Cavitation in a Water Pump and Valve - Excellent Visual and ...

 

[TwoHedWlf]

I've found most of my filters behave like that one when out of the water, not really an ideal test. I figure they lose sync without the damping of the water. You could try wrapping a few layers of tape around the impeller shaft, see if that helps for a quick cheap test if it's worn.

 

[BIG FISH BOB]

The armature of the pump is either bent or obstructed...... The armature is the center of the motor that spins. Really clean it out...... if it still make noise....it's just a matter of time. The filter could work for a week, a year, or annoy you for years.

 

[Monsterkeeper0223]

I am having a knocking noise on my fx5. I cleaned out the motor and the impeller. Impeller looks good so I put some silicon grease on it to hopefully make it turn smoother.

I turned on the filter and it sounded quiet for about 5 minutes then the knocking started again. Sounds like a clicking/rattling type of noise.

I also have an fx4 and fx6 and those are as quiet as a mouse.

Has anyone faced this issue before? If so how did you fix it?

I have a few times with my fx6’s and all I do is wash it out and wash the motor out and put it back together and always quiet again