silent running

I've had a bit of a problem with a 'sticky' clutch pedal for a while, at first it just felt a little reluctant to return and I noticed that the clutch release spring was missing from under the intercooler. Replaced that and it felt better but still not quite right. When I put the new spring on I thought it was odd that the clutch release arm/fork didn't seem to be under any real pressure from the clutch itself and could be just moved back and forth by hand, but the clutch worked and I've never really adjusted or fiddled with a clutch myself before, so I didn't think anything of it.

Recently the pedal's been slow to come up / staying half way down after changing up a gear following hard acceleration, but gentle driving doesn't cause the problem at all. Looking on here, it seems like a lot of people have had similar problems and after checking the spring, next port of call seems to be to bleed the slave cylinder or change the fluid completely. Not too tricky or so I thought, having bled brakes a couple of times before...

Upon opening up the reservoir and sucking out most of the fluid, it looked more like Guiness than the pinky or yellowy colour I was expecting. Straight away this suggested to my non-expert eye that the old fluid was done for anyway and changing it could only improve things greatly.

So please tell me what I've done wrong!

1. Took lid off reservoir, sucked out old fluid, topped up reservoir with fresh. Left lid off.
2. Pressed clutch pedal and simultaneously opened up bleed nipple, then closed nipple and pulled pedal up off the floor by hand - it wouldn't return on its own.
3. Repeated step two until I'd seen a load of bubbles/discoloured fluid come through and finally started seeing the fresh stuff.
4. Closed nipple, put reservoir lid back on, and pedal still stuck on the floor, unable to come up of its own accord. Looking at the system as a whole, I couldn't actually think of why there was any reason it should??? - The actuator rod on the slave cylinder wasn't actually solidly joined to the clutch arm, there was no spring pressure in the clutch arm itself anyway and the clutch release spring was too feeble to do much in any case. Somehow the system had worked before I fiddled with it though!
5. Now tried holding the slave cylinder rod in, reasoning that there could be a big air bubble just sitting in there being bypassed by fresh fluid coming down from the reservoir. Repeated the same steps as before, this time with more air bubbles appearing. Just for good measure I ran well over half a litre of brake fluid through the system, keeping the rod pushed right in. This time the pedal actually seemed to be able to push the rod out, but it was very slow to go back in with the pedal up, and as before there is virtually no feel in the pedal at all - no resistance to pushing it down, and no force to bring it back up on its own.

Help! Where have I gone wrong? Should I have kept the lid on the reservoir all the time, only taking it off to top it up? Should the rod stay in or out during the process? Even with a perfect hydraulic system between master and slave cylinder, I can't see what it is that is supposed to bring the pedal back up? Is it right that the clutch release arm doesn't seem to be under any kind of pressure from the release bearing? Surely it should be 'engaged' all the time, exerting pressure on the slave cylinder rod unless the pedal is pressed down, which will then counteract this force and disengage the clutch? Is this an engine out job to realign or replace the release bearing? Someone help me before it gets too dark to work on it! Cheers

Turbotits

iTrader: (2)

I think there a spring in the clutch master cylinder that returns the pedal,This could well be broken.

silent running

Aha. Well if that's so then you've made my weekend...I was having visions of getting the gearbox off just to adjust a clip or something. Which I may still end up having to do, but I'll look into this master cylinder spring problem. So is it right that the clutch release arm can just be pushed back and forth and doesn't press against the slave cylinder rod?

T5OLF

iTrader: (4)

It may not be connected to your problem....but i had the same thing, clutch pedal was fine when driven steady but give it a bootfull and the pedal only came halfway back up. I checked the spring on the arm and it was missing, fitted a new but made no odds.
A week later the clutch failed, it had pulled the centre out - did not lose drive but could not disengage the clutch. New clutch and flywheel fitted from group buy on SN and all is well.....for now.

morpheous

iTrader: (9)

Strip the slave cylinder down and clean up the piston,dont rag the seal and make sure the return springs on the clutch arm,also when you get the slave working correctly you can set up the pedal ,its adjustable.

ST AYE

Very dirty fluid may indicate worn a seal. The master cylinder should have a return spring if this has broken the cylinder could well be damaged, which would cause undue wear to the seal.

thedrill

Hi there, just changed the master and slave on mine yesterday because I was having similar problems to what you have described..I also had fun bleeding the clutch , and found the only way to get a good pedal was to compress the slave cylinder rod right the way home whilst undoing the nipple and have an assistant pressing the pedal up and down (needs pulling back up with foot until pressure returns) I also had my finger over the nipple slightly when pressuring up, to stop air returning back into the slave.

Hope thats of some help.

silent running

Cheers for all the replies, very useful. I've just done exactly what you said in the previous post and now I've bled almost a litre of brake fluid through it, with the slave cylinder removed and nipple pointing upwards, clamped fully shut - but still no return on the pedal at all. I've also found a high level nipple up by the o/s turret that I didn't notice before, so I bled that out first then did the slave cylinder, but still no return pressure yet.

I can't see how there can still be any air in there and if so where is it? I've got the slave cylinder out and in a perfect position to bleed air off; I've got an extra bleed point at the highest point of the system...what am I doing wrong? Should I keep the pressure cap on the reservoir while I bleed the fluid through?

I'm just about to get the master cylinder apart and dismantle it now. Slave cylinder piston and spring were OK when I accidentally blew it open last night LOL.

The big question that I still need answering is: should there be any force exerted on the clutch release lever by the release bearing/clutch assembly? Surely the lever should be pressing back against the slave cylinder rod when at rest, with outward pressure from the rod pushing against this when the pedal is pushed down?

thedrill

Hi again, There will be no pressure onto the clutch slave rod from the clutch arm as it should be held back with the external return spring, the slave cylinder rod is free floating with only a lightweight spring internally pushing it out into the clutch arm pivot point.
If your stuck I have a perfectly good slave and a working master for you to try out.

silent running

Ah, right, ok. Well the slave cylinder's got a lightweight spring in it for definite, and it's working. I just took the master out and dismantled it as far as I could and there's definitely a spring in there somewhere pushing the piston out well; feels smooth and strong. No evidence of any brake fluid leaks coming through. Lengthened the rod by a couple of turns while I was there.

So now it's down to putting it all back together again. The system is weird though - not like any of the manuals show. From the master cylinder the pipe goes to a splitter where pipe A goes off via a very long route and then back to a nipple at the highest point of the system. Pipe B goes off to the slave cylinder.

So the plan is:
1. Top up reservoir
2. Clamp slave cylinder shut
3. Open high level nipple and bleed until no more air comes through
4. Open slave cylinder nipple and bleed until no more air comes through AND pedal pressure comes back
5. Put lid back on reservoir and unclamp slave cylinder
6. Mount slave cylinder back on gearbox and spring on clutch release lever
7. Job done?

One other technical hitch I've encountered...I had a look at the release lever with the boot off and it can be waggled about all over the shop, left and right , back and forth, even up and down a little. Noticed the pivot rod seemed to be sticking out of the side of the gearbox and moving with it, so I pressed it in and it seemed to tighten up the lever movement. But shouldn't there be something holding it in tightly, not just a greased pivot rod that seems about to fall out at any minute?
6.

WUZ

iTrader: (14)

As per your other post, the Pivot shaft is secured by a blanking plug. if this is not in, the Pivot shaft can slide out of the box meaning it is not fully in and you'll lose one of your "fulcrum/pivot" points. this will explain why the release lever is able to wobble around. You might need to check the clucth plate and release bearing for damage

Russell

silent running

So when I first looked at it, the pivot shaft was sticking out the side of the 'box by a couple of cm. I pushed it in by hand so it's just proud of the hole. I need to get everything back together and driveable today, so will I be OK to leave the pivot shaft where it is? Or should I push it in as far as I can by hand and then bung it up somehow to keep it from coming out - as a temporary repair until it can be looked at properly?

silent running

And I thought all my troubles were over once I'd inspected the master cylinder. I'm starting to get really ****ed off now. This should have taken an hour tops, and instead I've wasted my entire weekend on it. I've been bleeding the fluid through for at least twenty minutes, that's another whole litre of brand new fluid gone and still no pedal return pressure. When my other half's pumping the pedal up and down there is simply nothing pushing back off the floor at all. With the system bled (or what I think is 'bled'), the nipples tightened down so the system is sealed shut, it's got a totally solid pedal - you can't press it down at all. The only way to move the pedal is by opening a nipple, then the pedal drops to the floor with virtually no resistance and sticks there.

What the hell am I doing wrong? There CANNOT be any more air in the system anywhere. I'm at my wits' end. Am I doing something really stupid once I think it's bled and it's something so obvious that's no-one's mentioned it? Can someone write out a moron's guide to bleeding a clutch system, including even the most obvious things that shouldn't even need to be said? PLEASE!?!?

WUZ

iTrader: (14)

once it is pushed all the way in, it should sit 15-20mm inside. this is enough room to be able to screw on th eblanking plug and nip it up.

the clutch pedal WILL NOT RETURN ONCE IT IS PRESSED WITH THE NIPPLE OPEN. that is how it is on a hydraulic clutch, when you bleed the clutch you do not want to push the pedal all th way down, only about 90% and then lift it back to the top and start again.

I do feel that you current problem aren't related to air in the system. This would just make ofr a spongy pedal, nothing else.

look like you need to check out the clutch master cylinder.......................again

Russell

silent running

Cheers for the help, it's really appreciated!

OK so the pivot shaft, I'll press it in, bodge a plug for it for the moment and hope the clutch is OK. That I can handle I reckon.

I can see what you mean about the pedal not returning but my problem is that I can't get '90%' - it's either stuck at the top or stuck at the bottom; there is nothing in between. The only way I know the pedal's connected to the hydraulics at all is because I can see a little of the reservoir fluid go down on every 'up-stroke' and a little of it flows out of the bleed screw on every pedal down. There's no feeling in the pedal that fluid's being squeezed out or anything though....

...Half an hour later...

This is turning into the worst weekend of my life. I just spent another 20 minutes bleeding it out REALLY carefully - barely opening the nipple each time, closing it before the bottom of the pedal stroke, opening it after the start of the down-stroke, so far so good, very slight back pressure starting to be felt, but no more bubbles at either nipple. So nipped up all the connections tight, pedal at top of travel, released the slave cylinder clamp (it popped out half a cm or so, not the whole way), bolted the slave cylinder in position against the clutch lever, and went to give the pedal a try. Felt hard at first, then pushed down ok and I think it came back sort of, then pushed it again and it seemed stuck not wanting to go down, then pushed a little harder and it went straight to the floor. Hooked it up and back to square one - no feeling of any connection to the system.

You can probably guess what I found in the engine bay - brake fluid over everything, slave cylinder rod wedged hard against the clutch release lever so it couldn't move, piston wedged 3/4 out of the cylinder with the seal wrecked and a gouge now in it.

So I must have HAD a bled and ready hydraulic system before, but instead of pedal and slave cylinder moving back and forth smoothly, it's just totally unpredictable and crap. Time to rip the entire system out and start with new cylinders and maybe even pipes? Perhaps even taking all the plumbing out and bleeding the whole lot on the bench?

silent running

Any more ideas? Replacement master and slave cylinders are on the way. Could it be the convoluted pipework that's at fault? If I want to prepare the piping for the new cylinders, what should I do...open up the nipples and drain the whole system out?