Clutch query?

[rpjg_1975]

Quick query for anyone....

Just bought car back out on the road and from time to time the clutch fails to come back up properly. Comes up about to the biting point so will drive ok. If I pull the pedal up with my foot it is fine until I put it back down again then the same thing happens. Am I right in thinking it will be the slave cylinder and if so is it a nightmare job to change?

Cheers

 

[pylonracer]

I had exactly the same problem after putting my 944 back on the road after three years, seemed to go away after a few days of use.

Make sure the system is well bleed out and has plenty of fluid, the clutch slave cylinder is not too bad to work on, it is a little bit tight but OK.

Baz

 

[pauljmcnulty]

You'll see if you're losing fluid, as you'll need to be topping it up. I've just had mine changed as it was showing a high water content, quite possibly original. [&o]

You'll not see the slave leaking. It could also be the master, but this would show leakage, or the hoses. Slave is an easy job - I did mine myself and I struggle with anything above tuning the radio. I still have the imprint of the starter motor on my forehead 5 years later, though.....[&:]

 

[Fen]

I have had this, though I can't remember the cause. I don't think it is rellated to losing fluid; I think it's just that a return spring isn't powerful enough. Don't take that as gospel, however.

I don't recall it being a symptom when my clutch slave was on the way out. In fact I think it was my Turbo that did it after it went back on the road and when I mentioned it to my indie he fixed it but it took a couple of attempts.

 

[rpjg_1975]

Right, thanks everyone. I will keep an eye on it then. Don't think i've lost any fluid as I checked all the bottles yesterday. The small brake fluid one at the back left as you look at the engine was a little low but nothing major. It did it the odd time before I took it off the road and I only bought it back out a couple of days back. Will be using it a bit more over the next week or so, so I will keep watching and report back

 

[swright]

ORIGINAL: rpjg_1975

The small brake fluid one at the back left as you look at the engine was a little low but nothing major.

That's the clutch fluid reservoir, so if that was a bit low it could well indicate a leak.

 

[rpjg_1975]

ah, will keep a watch on that one then. any ideas how I bleed the system or does it self bleed?

 

[swright]

I'm not 100% sure as i haven't bled a Porsche one yet but id expect there to be bleed valves on the slave and master cylinders. Just like bleed valves on brake calipers.

 

[pylonracer]

There is a bleed nipple down on the slave cylinder near the starter motor, you will need a basic brake bleed kit ie a jam jar and a length of hose. I do not use one of the fancy self sealing hoses that you can buy.

The reason for not using the self sealing type is that the nipple is very loose in the slave cylinder once it is off of its sealing face and can easily draw air back into the system via the screw threads.

The way I carried out this operation was as follows, place a small ring spanner on the bleed nipple (dont undo at this stage) push a piece of rubber pipe a couple of feet long onto the nipple, place the other end of the pipe into a jam jar which is about 1/4 full of brake fluid. Get some one in the car to push the clutch pedel to the floor and hold it there, now undo the bleed nipple a small amount until the fluid starts to flow down the pipe and into the jar. As the fluid flow slows down which is very quick with a small hydraulic system like this, tighten the nipple back up, now tell the person in the car to let the pedel back up (in your case they might need to flick it back up with their foot) now repeat this operation until you get fluid with no air going into the jam jar. carefully monitor the level in the clutch fluid resevoir and top up as required, if you let this fluid run out you will have air at the top of the system which will take longer to bleed through.

It is important to understand the seqeunce of this operation, we are pressurising the system and letting the pressure and air expel via the bleed nipple, but before we allow the master cylinder to draw more fluid in we block off the nipple by tightening it up. With the self sealing one way bleed pipes that are avaliable this operation is done automatically but you run the risk of air getting back into the system via the loose threads.

WORK SAFELY, use the correct jacks and stands as you will have one person under the car (you) and someone jumping around inside the car.

Baz

PS check that you dont have fluid leaking from either the master cylinder, most likely visible by looking up at the pushrod that comes off of the pedel, or fluid around the slave cylinder, correct as required.

 

[peanut]

its more likely that the seals in either the slave or master cyclinder have perished and are letting fluid past . This means that after you press the pedal down you'll lose pressure in the system as the clutch forces the fluid back past the seals under pressure which will reduce the return pressure on the cyclinder pistons and therefore the pedal.
If its been standing that long I'd replace the brake master cyclinder and clutch master and slave cylinders too .You use seal repair kits but you need to be meticulous about cleaning the cylinders and pistons and if it doesn't work you'll have to dismantle it all again.
The easy test to confirm this is to press and release the clutch pedal and note how far the pedal returns.
Then press and hold the clutch pedal for 20-30 seconds .If the pedal doesn't return or returns less then you have either a fluid loss or the fluid is escaping past the cylinder seals under pressure and you won't be able to change gears

 

[rpjg_1975]

This may be a silly question but if it is the seals would it do it all the time or not? I only ask because driving it back last nite it was perfect and from my limited experience of the problem it may do it, then be ok for a while before going again?

 

[peanut]

its not happened to any of my cars for quite a while now so I can't remember. I think if you shift the clutch pedal quickly there is usually sufficient pressure to change gear. Its when you ride the clutch or hold it down a while you'll get pressure loss past the seals. It could be a problem with return springs maybe. I'm not too familiar with 944's all my work was on MGB's and Datsun 240Z and earlier cars .
I believe there should be a return spring on both the pedal and the slave cylinder.
If the seals have gone you'll usually see the fluid go cloudy and eventually black

You are going to need to get a Haynes manual if you intend doing DIY on your car. Take a look in Clarkes Garage under Garage Manual section
http://www.clarks-garage.com/

 

[picopro19k78]

I had the same problem about 3 weeks after buying mine last summer. Couldn't see any leaks and fluid ok so got into footwell and sprayed Duckoil with a straw attachment into the top of the peddle. Appeared as if the spring was strong enough as you could, as you've said, be flicked back up with my toe. Haven't had the problem again (yet)

 

[rpjg_1975]

quick update, seems fine today, fluid a little down so topped up. can't see any fluid anywhere so will keep watching. got a haynes manual when I bought the car which has been helpful on several occasions and I will save that website for future use.

goes for mot tomorrow so fingers crossed []