Very Loud Fluval U4, Help!

[xamy_valox]

Still having no joy. I took the filter apart this afternoon to see if something was trapped or catching but apparently not? I have taken the bag of coral gravel out and it doesn't make a difference, still just as noisy as when it is in.
I have contacted the shop I bought it from via e-mail (good old eBay =\) and will see if they will replace. I can only think its faulty? It sounds like the impeller is catching on something but when I look at it, it seems fine?

 

[snazy]

I've got 3 Fluvals and they's absolutely no sound from them Yours has a problem, whether improperly clipped media inside, the motor has caught something or it is faulty.
Check the impeller

 

[xamy_valox]

I have done, can't seem to see anything wrong with it! It spins fine, nothing blocking it, perfectly straight! Mine has got a little quieter since its bee back in the tank an hour or so, but still not silent as everyone else is saying theirs is =[

 

[Mamba]

Sounds like you may have a little problem as I have several U Filters, U2, U3 and U4's in all my tanks and have never had a problem touch wood.Mine are all very quiet.

I have read the above and would like to make a suggestion to isolate the problem.

Have you ensured that the top end of the filter is clipped securely into the top of the clamp? When new these can be a little tough.

If yes then take the filter out completely, minus the bracket, put it in a bucket of dechlorinated water and test it without the bracket attached. Ensure of course you have a bucket deep enough. If it is quite then it's something internal to the tank and how it's fixed.

If it's still noisy, un-clip the motor assembly from underneath so that only the motor is in the bucket. remove the impellor itself by turning it upside down and tapping the back. It's held magnetically so should fall into your hand or you can cheat and remove VERY carefully with a pair of tweezers/small pliers. HAve a look inside the impellor housing to make sure there's no detritus in there and check the impellor again and make sure each blade is identical and has no chips etc out of it. It takes very little for an impellor to cavitate.

If all seems ok, submerge the pump in the bucket facing up and turn the pump on for a few secs to determine whether the noise is still there.

Let us know the result, it may point to the problem. It's as everything eliminating one thing at a time. Let us know how you get on.