986 2.5 manual - clutch pedal 'sticking'

[perleman]

Hi all,

THis morning it was very cold (for the UK), prob just above freezing. The clutch pedal was light for the first few inches of travel & kind of 'stuck' on return, and did return the whole way but felt lighter than normal. The car drove & performed fine, and as it warmed up the problem lessened but didn't completely go (after 40 mins / 25 miles driving). Any ideas?

[Qtwo]

Since none of our usually good experts are on line this morning maybe we can at least get you started on your diagnosis and correction.

Check the on-line instruction manual to see if your vintage car is fit with a hydraulically actuated clutch. The manual should have very explicit instructions

to bleed the clutch if it is hydraulic. If hydraulic, locate the slave cylinder. Now locate the clutch fluid reservoir and make sure it is topped off. Bleed the clutch with a helper to depress the clutch pedal. It should be a simple fix if you do have a hydraulically actuated clutch. If it is an electrically actuated clutch then you will need appropriate instruction which I do not have. A word of caution, use only the specified clutch fluid if needed.

If none of the above works, stay on line with RennTech because someone will have specific knowledge to help you.

Good luck,

[fastboydave]

Sounds like you have air in the system (if hydraulic) which means you potentially have a leak somewhere (slave cylinder/master cylinder). As you 'operate' the clutch, it will get better, this is typical of air in the system. If it is not hydraulic, then maybe the clutch is on way out??

[RFM]

Start bleeding the clutch - yes it is a hydraulic system - at the slave cylinder on the gearbox with a helper as mentioned above, if your problem come back or even not disappears trey to locate the leak.

[geza]

If the feel has gradually deteriorated, then the circuit could have air, or the clutch master cylinder or clutch slave cylinder could have sealing/internal leakage issues.

If the feel was suddenly different, could be a cracked pressure plate.

[perleman]

"If the feel was suddenly different, could be a cracked pressure plate."

THe feel was COMPLETELY different this morning. The bite is still about half way up & no clutch sipping. Does the pressure plate require removal of gearbox et al? If it is air in the system am I right in thinking a simple bleed will only treat the sympton not the cause. Should I stop driving it ASAP? And can you diagnose a cracked pressure plate without removing the gearbox? Thanks

[fastboydave]

"If it is air in the system am I right in thinking a simple bleed will only treat the sympton not the cause"

Yes. You've got air in there because something potentially has gone wrong. So, although bleeding the system may 'relieve' the symptoms for a few hours/few days, ultimately the issue will return. When the leak gets too bad, bleeding will not help and you will loose all clutch control (unable to disengage/engage gears). Remember, i think the fluid for your car is the same as the brake reservoir, so make sure its not empty!!??

For me, i'd just take it into a qualified dealer, and get them to diagnose/sort it. If its a slave cylinder or master cylinder, as i understand it they aint easy to do!?

[perleman]

I have just been to see a specialist & he believes the clutch to be at fault, although it is not slipping he says it is heavy & the bite is near the top. The clutch pedal is also 'creaking'. He visually inspected the slave cylinder & found no sign of leaking. My question now really is, obviously some air has got introduced somewhere, will changing the clutch (which is expensive) be likely to eliminate the issue - as I only want to do this if it is neccesary and like I said, the clutch isn't actually slipping at all. I just don't want to have to pay for an uneccesary operation.

BTW it isn't a cracked friction plate as after pumping the clutch several times it returns to almost normal operation, where as with a cracked plate it would not come all the way back to the top of the travel apparantly.

[fastboydave]

If your 'bite' position is changing, then you almost certainly have air in the system due to a leak. Dont know where the leak is, but you must have one? Unless the clutch was bled incorrectly in the first place (which i have experienced from an OPC with my old Box S!) Also, you could have a worn out clutch release baring that will make your pedal hard to press. You get an audilble noise (creaking) outside at the rear and you feel it through the pedal. Part of your new clutch kit includes this baring i believe and the labour to do just that is pretty much the same as a full clutch anyway. If hes the expert, get an agreement that if this doesnt solve the issue he doesnt charge you for the labour or something?? How many miles has your clutch done??

[perleman]

Hi,

It's done 42k miles, but over 9 years, with plenty of London start-stop driving. I have now been to another independent specialist who said my clutch bite is about 75% of the way through so I am now aware that that will need doing in the next 5-10k miles, however I am a little concerned about the clutch not wanting to return as I don't know if that is related to the impending clutch failure.

To drive now it is pretty much fine although the pedal is slack at the top bit of travel. When the car is left overnight the clutch needs a few operations to get back to 'normal' - this makes me think that the master / slave cylinder might have a -tiny- leak, (as if it was bigger than that it would quickly be undrivable). There is no sign of leaking under the slave cylinder, and the Porsche mechanic I spoke to said master cylinder failure was so rare that he'd never done one. I guess my worry is that a new clutch won't fix the actual problem, even though it will need one put on soon

[fastboydave]

When i had my accumulator go (on my 996TT) the pedal went slack and the bite was on the floor. The pedal would also stick half way (as you describe). As i used it the bite improved and the pedal returned to home position although not perfect. Basically i was loosing fluid and air was in the system giving rise to the symptoms, which sounds the same as you. They replaced the accumulator and bled the system, however, i still was experiencing similar again as you decribe. They said that the air in the system can damage the slave cylinder and they need to replace this too. This was subsequently done and then the pedal was fine. Incidentally, no obvious sign of a leak on my slave cylinder too. So i would suggest you dont need to see a leak for the cylinder to be bad??

Your system (although) slightly different (no accumulator) sounds as though it is behaving similar to mine and even if you replace the clutch, this will not sort the change in bite etc that you are experiencing? This needs sorting. Just because he hasnt seen a master cylinder go, doesnt mean to say it isnt? There's always a first time, not saying it is ofcourse. Anyway, with your pedal feel as it is and him not removing the parts to inspect the actuall clutch, i would suggest that it is a very wild guess on how much 'life' is in your clutch?? At the end of the day, i suppose you are in their hands a bit......

You any where near Wembly?? I know a couple of well clued up guys near there where i had my car from? They know their stuff......

[perleman]

Hi,

I am close-ish to Wembley... the thing is, sorry if I wasn't clear but the bite never moved, just the postion the pedal returned to after releasing it. It is now pretty much back to normal so I'm going to leave it for a bit and see if the problem re-surfaces - Is it possible that any air has been pumped out? I'd love to have your recomendation in Wembley, is it Jaz? I really need someone I can trust to only do what is totally neccesary to fix the problem if it comes back.

[fastboydave]

Still think its air or bad cylinder(s). As you use it, you tend to pump the air out if there's a leak, so it does improve, its like pumping your brakes when you've lost pedal. Incidentally, check your brake fluid reservoir is at max, as thats the same fluid i believe if it look low, you definately have a leak. I'll send you a message with the guys details and website. Dave.

[perleman]

The clutch 'sticks' down in the morning after it hasn't been used for 14 hours, and after a few operations, it is pretty much back to normal for the rest of the day. It also makes a 'creaking' noise on operation, mainly when warm. Should I actually bother getting it sorted - or wait to be stranded by the road at a random point in the next 0-12 months? Will it potentially do more damage if I leave it?

I can't bleed it myself - not technical enough, live in a built-up area with no facilities etc. I have spoken to a tech and he has told me the following:

* One of the cylinders is likely at fault (master / slave)

* The slave appears to be dry on visual inspection

* the master can't be inspected without doing work.

He suggests replacing the slave first, which is most prone to failure & easyest to get to, at about 170+ vat to see if that's the issue. If he removes it and it isn't faulty he still suggests replacing it once he's done the work to get to it, to reduce the chances of future failure. If there isn't a fault with that he is pretty sure it will be the master cylinder, at a similar cost, and is fairly convinced that replacing that will cure the problem. Does this sound right? I'm braced for expense now and am considering replacing the clutch at the same time just to get it done (pedal is very heavy & bite is high up although not slipping yet). The car 'juddered' a bit when creeping up a hill in traffic in 1st gear just using the tick-over (foot off gas), so does this mean I might be needing a new dual mass flywheel too though?

Edited November 19, 2007 by perleman

[colinpbarrett]

Hi Perleman,

Can you advise what solution eventually solved your problem? I have noticed the exact same issue on my car (2001 986 S - 33k mls). The temperature has been as low as minus 6 the last few nights and I began to notice a very slight sticking in the clutch yesterday evening. This morning (after an exceptionally cold night), the problem was a lot more pronounced. The clutch isn't slipping and was catching most of the way as usual. However the pedal felt like it was 'sticking' when I pressed it and was delayed in returning immediately to the upright position. The clutch also felt 'semi-engaged' when it was in gear even when the pedal was in the fully upright position. This caused the engine to rev highly when gas applied and the car to feel like it had inadequate power. The sticking got progressively worse after a 40 minute city drive.

The brake fluid reservoir is full (I believe this is also the source for clutch fluid - it this correct?) although I can't get my mechanic for another five days and I don't have the technical savvy to bleed the system myself. Did bleeding temporarily solve your problem and can you advise if the issue turned out to be a leak in the master or slave cylinder?

Cheers,

Colin

Edited January 8, 2009 by colinpbarrett

[RFM]

Colin,

Looks like you have mentioned in your post two contradict facts: " the clutch isn't slipping...... and further: the clutch also felt semi-engaged when it was in gear even when the pedal was in the fully upright possition. This caused the engine to rev highly when gas applied and the car feel like it had inadequate power". This is slipping IMHO. I'm almost sure your car is suffering with a mechanical clutch issue, rather than a hydraulic issue. I could be wrong of course.

[PJsSCW]

. . . However the pedal felt like it was 'sticking' when I pressed it and was delayed in returning immediately to the upright position. The clutch also felt 'semi-engaged' when it was in gear even when the pedal was in the fully upright position. This caused the engine to rev highly when gas applied and the car to feel like it had inadequate power. The sticking got progressively worse after a 40 minute city drive.

The brake fluid reservoir is full (I believe this is also the source for clutch fluid - it this correct?) although I can't get my mechanic for another five days and I don't have the technical savvy to bleed the system myself. Did bleeding temporarily solve your problem and can you advise if the issue turned out to be a leak in the master or slave cylinder?

Cheers,

Colin

I too am having this problem of the clutch pedal sticking half way up... I just replaced the clutch so, it doesn't slip . . . but, the pedal "sticks" half way up and i have to help it the rest of the way up with my foot everytime I shift. . . after I start to help it, it springs up fairly rapidly to the top of its range. half way up, the clutch seems to be fully engaged (fairly low bite also noted) it does not slip what so ever though . . .

Any Ideas???

Thanks in advance,

JP Hooie

[RFM]

I would bleed the clutch system again to start with, if no result check for leaks and replace the master and/or the slave cylinder when leaking.