Some things to check

I am having serious problems with my clutch. Changed clutch, IMS, etc. a few months ago, and have had this problem since then, though it has gotten worse. At first, I thought the different clutch feel was due to a new clutch, but it has progressed.

Recently, I have had to have the pedal fully depressed to disengage the clutch. The instant the pedal was off the floor, it would engage. It has progressed, and now it is not disengaging at all. I have bled the clutch twice, once without the power bleeder, and once with it. No change. Also both times showed no air in lines.

Pedal pressure is lighter than it should be, but there is still enough pressure to return the pedal. (Usually). There is no noticeable leakage at the slave cylinder or the master, and I haven't noticed a drop in fluid level.

Is there any part in the system which is more prone to failure than others? I hate to start throwing parts at a problem, but I am not sure how to troublesoot past where I am. Next step is the stealership. If you think rates are high in the states, you should try Germany!

... flow and pressure coming out. Sorry i don't have enough experience to know what is the weak link.

Grant

I hate to be the bearer of bad news but if the thrust bearing on the crank is done the crank will move back and forward. A friend found his bearing in the pan . He could move the front pulley almost half an inch. The car ran great , but the clutch engagement was terrible.

Are you keeping the clutch pedal fully pressed to the floor the entire time you're bleeding the clutch?

What year is your car? (Later model years may require toggling of the ABS -- I think -- unit to get the entire system bled)

I am keeping the pedal depressed. Not sure about the ABS, but I haven't read anything about it in the Bentley manual.

I am going to replace the slave cylinder and see if it fixes the problem. I will know in the morning. I'm picking up a master cylinder and a slave cylinder, just in case.

Your problem does sound hydraulic, given that it wasn't great after your clutch R/R but has gotten progressively worse. I think you are on the right track the the MC and SC replacement. Best of luck!

NBC but I have an 84 Alfa Spider that years ago had a leaky slave cylinder, I successfully replaced it and a month later, the MC started to leak. Replaced the MC and then my clutch pivot pin sheared! All is well now but I always amazed how it seems that one thing leads to the other.

dghii
2000 Boxster S 6speed 112k miles

Thanks for all the comments. I replaced the slave yesterday, master today, and pressure bled the system. No change. I guess the comment about improper torque on the pressure plate could apply, though I followed the books, and torqued in two stages. I think I will have to give it to the dealer on Monday and hope for the best.

First of all what year / model Boxster are we talking about?

I have had my share of clutch issues with similar symptoms; where my clutch grabs 1-2mm off of the floor, and sometimes drags even on the floor making a shift into First at a light difficult. My issues would get worse after warm up.

Q1: Does your issue get worse on a warm engine? i.e. after 30min of driving its worse than a cold start?

Q2: Have you pulled your slave to verify:
a. You dont have a leaky piston (failed slave internally)
b. The nipple that actuates the clutch ARM on the end of the slave rod is plastic and the rod is metal. I had one issue where the nipple started to crumble and as it did the rod was shortened thus not pushing the clutch arm all of the way in when the pedal was on the floor. Pull slave and inspect rod.

*Pulling the slave is easy. Reinstalling the slave nearly kills me. Its such a long reach with no leverage and really needs to be muscled back in. I finally built a tool to push the slave in and hold it while I reinstalled the one 13mm bolt.

For my issue, which was partly due to my 3.4L conversion changing some clutch geometry a bit, I ended up making an adjustable slave rod and reinstalling it 5-10 times playing a game of high - low on its length until I came to the best length where the clutch would completely dis engage and the clutch would not slip under full load (3rd gear redline).

I also had to shave some of the plastic off of the back of the clutch pedal for an extra few mm of travel.

Good luck.

In fact, it is problematic enough that I would guess a mistake there as being a reasonably likely cause of failure.

You might consider pressure bleeding the clutch system with a friend, or assistant. If this fails, then it rules out the slave and master as long as the slave pin was put in the proper position. If the afore mentioned has been done and there are still issues, then the pressure plate was probably improperly torqued down. Those bolts and threads need to be clean and torqued down in a certain pattern. I personally like to do them in two stages.
regards

So, I was thinking about all the possible weak point in the system. Could someone who is familiar with the inner workings of the clutch answer this? Looking at the parts diagram (didn't want to post it due to copyright) the release arm pivots on a small piece, which snaps on to a ball. two questions:
First, is that ball adjustable, i.e., fore/aft?
Second, if that small piece had somehow fallen off, and the release arm was resting on the pin instead, would the system work as it is now, with the clutch working fine while engaged, but not disengaging completely?

Well,
I am pretty sure I put the clutch plate in backwards. I turned it around, so that the larger flange is forward (in other words, the pressure plate is farther aft than before), and the pressure plate had much more back-pressure when I torqued it. Can somebody please confirm that this was correct, because I am now having other clutch issues.

My current problem feels like a bleed issue, though I have recently replaced the master and slave cylinders and bled it repeatedly. When I press the clutch, it goes to the floor with almost no pressure. It does not come back up without a little nudge. When under the car, I can't hear any sounds from the tranny when the pedal is pressed.

with the slave cylinder removed, the plunger moves when the pedal is pressed (gently- I know the risk of pushing it out of the cylinder).

My thinking is this: If I somehow messed up the clutch plate installation, there should now be MORE pressure on the pedal, not less. Everything points to hydraulics.

I am absolutely out of ideas. If I have to send it to a mechanic, I would at least like to narrow down the problem.

BTW, For anyone in the San Diego area, Black Forest Mechanics has been extremely helpful.

Quote
IFlyLow
Well,
I am pretty sure I put the clutch plate in backwards. I turned it around, so that the larger flange is forward (in other words, the pressure plate is farther aft than before), and the pressure plate had much more back-pressure when I torqued it. Can somebody please confirm that this was correct, because I am now having other clutch issues.

My current problem feels like a bleed issue, though I have recently replaced the master and slave cylinders and bled it repeatedly. When I press the clutch, it goes to the floor with almost no pressure. It does not come back up without a little nudge. When under the car, I can't hear any sounds from the tranny when the pedal is pressed.

with the slave cylinder removed, the plunger moves when the pedal is pressed (gently- I know the risk of pushing it out of the cylinder).

My thinking is this: If I somehow messed up the clutch plate installation, there should now be MORE pressure on the pedal, not less. Everything points to hydraulics.

I am absolutely out of ideas. If I have to send it to a mechanic, I would at least like to narrow down the problem.

BTW, For anyone in the San Diego area, Black Forest Mechanics has been extremely helpful.

Boxster factory manual section on the clutch.

I have a line drawing of the clutch hardware exploded but it only shows one side of the friction disc. All I see that may be a distinquishing feature is the splined sleeve extends quite a ways from the clutch's center section.

To state the obvious you must be sure you have everything installed correctly. Not only the clutch disc facing the right way but the release bearing and release lever, too.

Do not forget the retainer spring.

Once you're sure you have the hardware installed correctly then of course comes the hydraulics.

Sincerely,

MarcW.

Yeah, thanks. I have the same picture from the parts disc, and I can't tell either. The first (Presumably incorrect) time iinstalled it, the large flange was aft. The pressure plate slid on easily, which I assumed was a good thing. Speaking to the mechanic at Black Forest, I found out that the pressure plate should have significant spring pressure on it while torqueing it. Once turning it around, so that the large flange was forward, the spring pressure felt more consistent with the mechanic's description.
Release bearing, lever and retaining spring are all correct.

I'm starting to think that the original improper installation possibly caused damage to the slave cylinder, event though it was installed only this summer.

the clutch hydraulic system was exposed to excessive clutch pressure the clutch slave cylinder seal (or?) could have been damaged from the overpressure condition. Another risk is the clutch's slave cylinder's piston was forced to travel into an area of the cylinder that it had never been into before. Corrosion, dirt perhaps could have damaged the piston's sealing or scored the piston and its cylinder wall.

(This is why when one bleeds the brakes he should avoid pushing the brake pedal all the way to the floor to avoid forcing the brake piston into virgin cylinder territory with the possible damage to the brake piston and cylinder.)

The result is the clutch hydraulic system can't build and maintain sufficient pressure to hold the clutch disenaged even though the clutch hardware is now correct.

There is another possibility that the clutch pressure plate diaphram spring has been damaged from being (WAG) over extended from the misinstallation.

Wish I could be of more help but even if I were there chances are I'd not be able to spot anything amiss. I've never had a chance to view my Boxster's clutch hardware up close so without some drawing, or picture...

Sincerely,

MarcW.

As an as side to my previous post, have someone push the clutch pedal while you watch the flywheel pulley for movement. I sincerely hope this is not your problem.