Just replaced slave cylinder now grinds going into second gear

you forgot to say MANUAL transmission????????
and step #1 on all M/T box clutch pedal fails (say pedal see?
is the fluid for THE MC to slave cylinder is dry.
check fluid under hood for cutch MC, master cylinder above
the CLUTCH PEDAL it is.
if dry or very low, and goes lower the MC or SLAVE is bad.
i replace them both for faster longer service life./
the clutch bad can be variable until all fluid is lost
one key clue,is
is can not start the engine unless in Neutral.
or can not shift to 1st gear to move car. ,from neutral engine running
or all gears grind as you shift.
or the canary gear REVERSE loves to grind first is early warning of clutch failures.

a new MC and slave is cheap, do not buy a new transmission until MC and slave are proven good. first.

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.

the gear grinding noise is because the clutch plate is not fully disengaging and the input shaft is still driving. If you did not use the same length of push rod then the slave cylinder is not moving enough to disengage the clutch. Check it out that with the pedal on the floor the piston in the slave cylinder should be almost to the edge of the slave cylinder . That is where It should be to be working properly

that sounds like a throw out bearing failure-is there any adjustment at the slave cylinder-it may be holding the bearing against the clutch and causing the noise-this thread may help-http://www.jeepforum.com/forum/f9/how-change-bleed-clutch-slave-cylinder-511531/- cheers Denny

no fluid in the clutch reservoir due to a failed clutch slave cylinder
time to replace both the clutch slave and master cylinder

Hi bosslady15,

First of all I think I should say that clutches do not make grinding noises - but transmission gears do.
However, a clutch that is not disengaging properly can make the gears grind when trying to shift from one gear to the next. Also a common source of noise is the clutch throwout bearing. This will make a "grinding" or "growling" noise any time the clutch pedal is depressed. In either of these cases, the only solution is to replace the clutch, throwout bearing, pressure plate and pilot bushing. These all usually come in a clutch kit. If you have an hydraulic clutch with an internal slave cylinder it is recommended to replace the slave cylinder as well and also the flywheel on on vehicles. I'm sorry I cannot be more specific because you did not mention what type of vehicle we are talking about here.

If the slave cylinder is leaking, replace the slave cylinder. You are loosing hydraulic pressure in the clutch and is the reason why it is not engaging correctly.

yo it could just be out of fluid!

If it is grinding too much to get into gear, you must have air in the hydraulic clutch lines. Use the bleeder on the slave cylinder to get the air out. You can have someone step on the clutch pedal as you would when bleeding brakes, but these usually gravity bleed if you let it run long enough. Keep the reservoir full. Once you shut the bleeder, press the pedal down to where pressure is felt, then quickly cycle it back and to this point over and over by hand. This gets the air out of the return port in the valve of the master cylinder. You should get a pedal that hardens at around an inch of freeplay or so. Now your clutch should completely disengage, thus letting the gears in the tranny stop, allowing you to shift into gear without grinding. Let me know if this solves your problem.

Replace master cylinder