new boat trim question

[Rich1540]

1998 50hp johnson spl ,on a welcraft 160ccf
my question is motor goes up perfectly nice and quiet but when i lower it whines real loud and makes some erie sounds and it will slowly fall if i let it sit awhile !
any ideas ! ive tryed to change the fluid and bleed it !
i read on here how to bleed it so i think im doing it right ?

 

[Rich1540]

Re: new boat trim question

could this be a seal in the cylinder bleeding by ,i would appreciate any help ,
Thanks Rich-just got the boat yesterday

i drained all the oil out and refilled raised it up and down ,then cracked it open again and let air out ,and repeated 4 more times and still bleeds down after sitting alittle while /almost a grinding noise /still goes up like its brand new just going down is the problem ?