D5 pump noise

I refilled my loop a few days ago as I was replacing my GPU and now the pump makes a knocking/squeezing noise but stops if I tip the front of the case up by 6 inches or so.

Is this just air in the loop or something more serious as it never used to make this noise at all previously.

Temps seem fine but just getting annoyed by this noise

 

It sounds like there may be air in the loop.

 

Sounds like it could be air but there's also the slight possibility of bearing wear that you can only check by removing the pump top and rotor and looking at both the bearing and the rotor.

If it was starved of water for more than a minute when filling it's enough to damage the bearing.

 

If the front of the case is tipped either up or down by a few inches the noise stops so I am hoping it is just air but it has not taken this long before to clear the air out of the loop- been around 4 days on and off

 

must be air as I keep hearing lumps of water falling in the rads so keep running it till the air bleeds I suppose- taking forever- never this long before