Replace slave cylinder

It sounds like something not put back correctly or adjusted. Was the slave cylinder arm push in when you bled the system? There may be air behind it. Did you use a pressure bleed system, slave up to Master. Lots of help in the links.

https://www.google.com/search?q=2005+6+hyundai+tucson+clutch+master+cylinder+replacement

https://www.google.com/search?q=2005+6+hyundai+tucson+clutch+adjustment

Umm...

A mechanical 'breaking noise' doesn't sound good. It's hard to diagnose a problem online without being there to see/hear the vehicle. But .. it may be that your clutch pressure plate has broken/ release/throwout bearing has broken?

It's difficult to see why the master cylinder should leak - unless it was incorrectly fitted in the first place?

Just to check ... The master cylinder is in the engine bay/compartment and is where you top up with clutch fluid. When a master cylinder fails it usually results in no pressure at the clutch pedal, not a leak.

The clutch slave cylinder is the one that does all the work. When you press the pedal hydraulic pressure is sent from the master cylinder to the slave cylinder - which then pushes the release/throwout bearing against the clutch pressure plate and 'disconnects' the driven plate .. allowing you to change gear.

The slave cylinder is the one that does all the hard work - it is located somewhere where engine and gearbox mate together, usually at the bottom right/left. It's usually the one that fails/leaks. It's quite easy to replace..

I don't think it is anything to do with reverse gear. It's more to do with the clutch pedal being depressed - and, I would suspect - something has failed.

The link below is generic images of a clutch:
clutch diagram Google Search

Basically, a clutch is 3 parts. There's the 'pressure plate' which bolts onto your flywheel. The pressure plate is a 'spring'. You depress the clutch pedal and the release/throwout bearing presses onto the centre of the pressure plate causing the 'fingers' - the springs - to bend back and take pressure off the driven plate - which is the link - the drive - between engine and gearbox.

If you have a leak your clutch will not work. This causes a 'grinding/crashing' noise when you try to change gear. The first thing you should do is check where the leak is coming from and do something about it.

The 'noise' that you mention may be due to the fact that the gears are 'grinding' as they try to mesh together without the use of the clutch.

The first thing you should do is check why there's a leak. It's difficult to see why a new master cylinder is leaking unless it was incorrectly fitted and damaged (pipes incorrectly connected..).

If it's the slave cylinder that is leaking - replace it. Easy job.

If Master cylinder and slave cylinder are ok - you have to look at your clutch unit. A clutch is always replaced with 3 parts ... throwout bearing/pressure plate and driven disk.

Does the car want to pull when sitting still in gear with your foot on the clutch? If so, I would say that your clutch is not fully engaging and could be the cause of your grinding when changing gears. If not then I would think the clutch is operating fully and the synchros are worn and need replaced. But either way, with metalic fluid being in the slave cylinder dust boot, the slave cylinder needs changed.

Bad transmission

replace the clutch

Check the fluid in your slave cylinder. you have a master cylinder for the brakes and a slave cylinder for the clutch. It should have a screw on lid and if it's full, you probably need a new one.

clutch is not disengaging when pedal is pressed
no hydraulic fluid
slave cylinder leaking
clutch master cylinder failure
air in system
clutch cable broken
take it to a clutch and brake specialist shop
not a clutch problem

Have you just replaced the clutch? Taken out the transaxle, and put it back in? Are you sure transmission was in good condition before this? If so, review your procedure carefully to be sure you got it all back right.
Watch the slave cylinder while someone depresses clutch. You should see the little plunger move slightly out and move the clutch lever back. The lever moves the release bearing inside bell housing into contact with the pressure plate. If slave cylinder doesn't move at all, try bleeding again. The plunger has to move when clutch is engaged.
I'm not sure what you mean by "will shift but won't go into gear". You mean it's actually going into a gear position and car won't move? Or it won't go into any gear, period. As if you had no clutch?

That cylinder is known as the clutch slave cylinder. It should push against the clutch fork every time the clutch pedal is depressed to allow gear changes. If it doesn't, suspect a faulty slave cylinder, or clutch master cylinder.

do this...

make sure the reservoir is full
engine off and pump the clutch pedal slowly about 5-10 times
while holding the pedal down have assistant open the bleeder on the master located in the trans

if you get a good squirt then your concern is the master
if no squirt then replace the slave

neither job is quick but the slave is 1/2 time