Clutch Release Bearing noise

[matty_et]

Hey guys,
Long time no post i know, i still get on here to check things out from time to time.
Lately i've had a problem with my MY06 Lib 2.5i 5 Spd man. When starting the engine and having it idling, foot off clutch and in neutral i have a slight whining noise that seems to spool up then die down then spool up again and so on. Its mainly on cold start ups and will continue to make to noise untill ive taken the car for a spin and things are warmed up. Im almost certain its the clutch release bearing as when i apply a slight pressure on the clutch pedal (enough just to take up the free play) the noise stops and when fully depressed there is no abnormal noises. Also while the noise was being made i have physicaly pushed the clutch slave cylinder/throw out fork in, in the engine bay in thus sliding the release bearing further away from the pressure plate. So it seems to be that the release bearing is not moving far enough away from the pressure plate and is creating a slight drag on the bearing and creating the whining noise.

Now heres where im stuck I have searched the net for any info and all i've really found is acouple of ghetto DIY's where people have made a bracket and fitted a return spring to pull the slave clyinder/throw out fork back, if i cant help it i dont really want to stoop to that degree. I have rang a Subaru service centre and described the problem and was told that on these engines the release bearing is in constant contact with the pressure plate (correct me if im wrong but it seems like unecessary wear and tear to me) and that the bearing is stuffed and when im stepping on the clutch im somewhat deading the sound of the stuffed bearing. My understanding is that if the bearing was stuffed the noise would be greater when the clutch is pressed/underload. Also i had the clutch and DM flywheel replaced under warrenty approx 65K Kms ago, i assume Subaru would have replaced the release bearing in the process but who knows. So i guess my question is, what actualy does bring the slave cylinder back in under normal circumstances. I dont think the piston for the master cylinder is directly attached to the pedal.. reason being for pedal free play adjustment, so its not as though the spring pulling the pedal back up is in turn sucking the slave cylinder in....or is it? Is there a spring in the slave cylinder itself or even in the bell housing? Is there even i bloody spring somewhere at all lol?

Any help or input will be much appreciated, its annoying that it has happened just now as i was just about to put it up for sale as i want to upgrade. i dont want to sell it with this noise and im not a fan of doing thing half assed.

Cheers

[smythie]

So i guess my question is, what actualy does bring the slave cylinder back in under normal circumstances. I dont think the piston for the master cylinder is directly attached to the pedal.. reason being for pedal free play adjustment, so its not as though the spring pulling the pedal back up is in turn sucking the slave cylinder in....or is it? Is there a spring in the slave cylinder itself or even in the bell housing? Is there even i bloody spring somewhere at all lol?

At least on my 3RB, there is a spring on the fork, though if anything it is applying a little pressure on the bearing

[matty_et]

Thanks mate,
Yeh i think your right in saying its applying pressure on the bearing (seems like unecesarry wear to me) and also if im not mistaken i think your clutch is a pull type whereas mine is a push type...whether or not that matters.

I did abit more research and found that some manufactures do indeed keep the release bearing in constant contact with the pressure plate, though not enough pressure to produce unecesarry wear. Is it possible to have a low tension spring inside the slave cylinder pushing the piston out? I assume Subarus slave cylinders would be pretty similar in design regardless of the model of car whereas you have a spring and i dont.

[smythie]

that slave cylinder on mine pushes on the fork if that's what you are referring to.

Having the bearing running all the time isn't going to hurt it anymore than it sitting on the shaft rattling along. Contrary to popular belief, bearings as a rule will not fail due to age or the amount of running they have endured. Failure of a bearing is usually a result of an incident in its life which either causes the lubrication to drain away from it, creates an irregularity in the surface of one of the bearing surfaces (inner race/face, outer race/face, rolling elements), or heats a surface such that it is no longer as hard as it was originally.

[matty_et]

Yeh thats true about the bearing.

Today i jammed the clutch pedal down and removed the rubber boot over the slave clyinder ram and noticed it was very rough, i cleaned it up abit and applied a little grease on the ram. So far so good, but time will tell.


Also when im refering to your clutch as a pull type i mean the throw out fork via the bearing actually lifts/pulls the clutch pressure plate spring fingers away from the clutch/drive surface of the pressure plate rather than push the bearing onto the the spring fingers to create slip as in a push/more commenly found clutch set up.

Apparently pull type clutches need less effort to operate thus can be of a higher tension for more powerful aplications. Im pretty sure the GT's have them, i assume the 3.0lt would have them and also my slave cylinder in installed in the reverse of yours in the photo.

Cheers.