Noise on gearbox when clutch pedal is pressed down

there is no air in a hydraulic system or if there is , the clutch will not disengage
if you have any sound when depressing the clutch pedal, it is most likely from the throw out bearing running dry when pressure is applied to the pressure plate fingers
so it amounts to this
if you press on the clutch pedal and you can readily engage first gear or reverse and you have steady operation when you take your foot of the pedal , the clutch system is working as it should
that means that any noise you get when pressing on the pedal is when the throw out bearing is placed under load and as there is no other part that is moving, that is the logical area
one point here --if it is an air noise and of that you are sure , when people press on the clutch pedal, to stop vehicle movement they also have the foot resting or pressing on the brake and a hissing noise here can be from a vacuum leak at the brake pedal from the brake booster
easy to check before pulling a box that doesn't have a problem

sounds like thrust bearing or bearings in gear box

What?! Really! The noise goes when the clutch pedal is depressed! So the noise goes when the release bearing (throw-out bearing) is engage? So how would that be a release bearing/clutch problem? If it didn't make a noise until the clutch pedal was depressed, it would be the release bearing! In other words its the input shaft bearing and/or counter shaft bearing in the gearbox. Stop giving people bad advice

if it was the clutch thrust bearing the noise would be there as soon as you put load on the pedal, so the noise will be coming from the spigot bearing because when you have the clutch pedal down a few inches the input shaft in the gearbox is almost stationary there fore the spigot bearing is then turning around the stationary input shaft causing the noise .when the clutch pedal is released the clutch plate is held tight by the pressure plate holding the input shaft at the same speed as the crankshaft there fore the input shaft and spigot bearing are turning at the same speed and not turning on each other and not making any noise .regards agwbk

I hope when the first clutch was replaced the throw out bearing was replaced. It sounds like you are either riding the clutch (foot resting on clutch pedal and partially depressing the clutch during normal driving) or the adjustment is incorrect. The throwout bearing should not contact the pressure plate unless the clutch pedal is depressed when adjusted correctly. The constant contact is what wears the bearing out prematurely.

If you notice a change in the rattle,when you depress the clutch pedal it is most likely in the clutch,or the linkage.The release bearing will most often have a squeal or a hissing sound.The clutch fork can rattle, if the ball pivot retainer is broken.You may feel some unwanted slack in the clutch opperation,and you may be able to adjust this out,but maybe not, with a hydraulic clutch.

sounds like the main shaft bearings within the gearbox itself. i would of said the release bearing but u already changed it. the main shaft doesnt spin with the clutch pedal pressed. check for oil leaks and check the oil level in the gearbox.

Can not seem to get the sound clip to work but from what you have said not only is it pretty obvious but also quite a common failure on Jeeps:

Thrust release bearing

These are part of a 3 in 1 clutch kit, as it is a box out job you may aswel do the clutch at the same time, also check the rear main oil seal (a cheap part that also may aswel be changed while gearbox is off)

Kind regards

Lloyd

it sounds like your clutch release bearing has or is colapsing.when you press the clutch the release bearing is under the most load hence the noise.gearbox out i,m afraid.Can you still get gears ok ?.Also the pedal box,s are prone to break on polo,s ,the symptom for that is like a squashy pedal and hard to get gears.if you can look up at the top of the clutch pedal where the cable mounts see if the bracket the cable fits in to is broken away at the top.

First check the oil level in the gearbox. The noise you hear sounds as though the pressure plate of the clutch is faulty. If every time you press the clutch pedel the noise goes away it points to the clutch. If this model has a manual clutch cable adjuster, try and adjust it to see if there is any inprovement.