Brent 89-GT

Sounds like you have tried everything. I don't suppose you were able to hone the MC bore when you did the seals. That may account for the air, though I would almost expect a leak inside at the same time if it wasn't sealing properly.

Before I went ahead with pulling the MC I would try the 944 trick just for kicks. Pushing fluid from the caliper bleeder up through the slave, master and back into the brake resevoir. I might use a couple small hose clamps at the bleeders to make sure you are not introducing any new air.

My blue hose was wet, and no matter what you think, replacing it, even with the MC out, is going to be a major PIA. Good Luck

cfc928gt

BTW, when I bought the new clutch master I bought it from one of the big three and it was a '***' brand (LOL, marketing must not have been involved in the name selection). I suspect that's why using the new plunger didn't work, it was probably just slightly smaller than the original porsche part. I'd bet if you bought a porsche clutch master you could just swap the plunger and be good to go. Replacing the clutch master was one of the worst experiences I've had with the shark. You'll know the blue hose needs replacing when you start getting brake fluid on the floor.

deliriousga

I'll definitely give the 944 trick a try tonight. I had seen where others have pressure bled from the bottom, but I couldn't figure out how to get pressure there. Brake bleeder is an excellent idea. If that works, wonderful, and if not then I'll order the MC and blue hose. I'll try replacing the inside parts with the ones from the new MC first and then change the MC if that doesn't work.

Brent - What do you use to hone the MC? How is it done?

Thanks guys.

GlenL

Well then maybe that's not it.

If the master is bad it should slowly go down under moderate pressure as fluid goes past the cup.

To be honest, I'm not too surprised that there is the same behavior after rebuilding the master. Been following this for a while and think the problem may be mechanical and not hydraulic. Hydaulic failures aren't as intermittant as this sounds. Also, the clutch opens (right?) and it is just that the pedal doesn't come back.

Could the pedal arm be catching or some problem with the helper spring?

deliriousga

The clutch does not open when the pedal is pushed in. It's always in gear. If you push the pedal down past the point where the spring pulls it down, it goes straight to the floor on its' own like there's no pressure behind it. I checked the clutch when the pedal was pushed down and it did not open, just sat there in gear.

I was thinking it might be mechanical too since I've done so many things, but if the clutch does not open when the pedal is pushed due to something sticking, then I believe the pressure in the hydraulics should make it hard to push the pedal in if they were air free. Not sure about releif valves, etc., so I could be totally off base with that.

GlenL

OK. Then I misunderstood the symptoms.

Sounds like time to replace the master. That'd be a good squirt of fluid if it was leaking from a line or fitting.

tammons

928 clutches are the pits. Whoever designed that system should be shot and there have been several times I was ready to take aim.

1st I would say replace all the clutch hydraulics, which you have done part of including the flex pressure line and clean out and really check the hard lines. The inner lining of a flex pressurized hydraulic hose can collapse and is very hard to diagnose. Once you have that all settled and sure its bled, time to move on the the mechanical part if you still have problems.

I recently had 2 clutches in a row that both had recessed capture rings that holds the TO bearing to the PP. That was after about 12-20k. The deeper it goes the less clutch you have. Sounds to me like yours is the master though but I thought that too.

FYI, I spent 3 days trying to get that damn hydraulic line back on the master a while back. It is in an impossible spot so be careful not to bend the tube when you take it off.

I think there was one guy here recently that rebuilt his from the inside. Smart move.

At any rate I fought with my hydraulics for 3 weeks since I had just done the clutch the year before, but as it turned out, mine was another mechanical clutch problem.

Sean79 5spd

It took four times to bleed my clutch slave. I opened the bleed screw and then applied compressed air to the small hole on the lid of the resevoir. In total , forced about a liter of fluid through. Each time the pedal resistance got a liitle better.

Strangest problem I have ever come across.

Sean

FlyingDog

I had the same problem after I replaced the chassis to engine soft line. If you pump it up and down a few times, does it pump up a little? Mine would go from no clutch to 1-2" with a little pressure at the bottom after several times of working it up and down with my hand. I don't know what the problem was, but I know how I fixed it. I set the power bleeder at 5psi and pushed the pedal to the floor twice. The second time there was a pop. Suddenly the clutch seemed to work perfectly fine. I haven't test driven it yet.

hupp

The 928 clutch can be a pain, but it is not overly complicated the solution to the problems are typically very simple. The simple type stuff that will drive you nuts and make you want to replace everything.

John,

I would not do anything dractic just yet. Based on what I've read, it sounds as if your hydraulic system has no leaks - you are able to install the pressure bleeder and it holds, so no leaks. If no fluid is evident in the cabin, your master is more than likely not the issue either. Use a bright light and take a look under the car, up past the steering shaft in the area under the brake booster and down this side of the engin bay and fire wall. Are any leaks evident? If not, your blue hose or master is likely not the issue. Your issue may be due to air in the slave - which can have drastic effects on the hydraulics. I'm making this assumption based on the fact that you mentioned that your clutch will operate a few times just after bleeding, then the pedal stays on the floor. Did you evacuate the slave after bleeding? Here is how I bleed my clutch: (I'm sure you know much of this, so sorry if I'm being redundant)

WITH SLAVE INSTALLED
-Remove pre-load at clutch pedal rod, but don't detatch. I like to do this because it makes it easy to actuate the slave rod by hand, which is done later in the process.
-Install pressure bleeder at reservoir, pressure to 10psi and open bleeder at slave.
-Pump the clutch pedal several times during the bleeding, and bleed until no air bubbles are observed.
-Close slave bleeder and remove pressure bleeder.
Now evacuate the trapped air from slave:
-Unbolt slave and pull back until you can get the boxed end of an 8mm wrench on the tip of the rod (through the inspection hole on the lower bell). This will give you leverage to push the rod in.
-Put a slight load on the rod with one hand (or use a helper), open bleeder with the other hand, push rod all the way in, close bleeder, led rod extend. Repeat until no air is observed.
Now remove any potentially trapped air from the master:
-Slowly push slave rod all the way in and release with bleeder closed. do this several times
-Install slave.
-Set pre-load at clutch pedal.

BTW,

I've had the pleasure of replacing my master, so I can help if you get to that point.

deliriousga

Well, I did hupp's 928 clutch bleeding ritual and tried the Shocki brake to clutch slave trick and still on the floor.

I ordered the clutch master, blue hose, ABS relay, shift boot and foam so I can hopefully get her back on the road after this weekend. About how long should the clutch master change take? Any info that may help make the "PITA" job easier are much appreciated.

Thanks!

tammons

If you have an incredible stroke of luck you should be able to just install it in a 1-2 hours. Its at a weird angle, and very difficult to get to, also the hard line is impossible to get started, so when you remove the old one be carefull you dont bend the line. If the hard line is still close to aligning you may get in one shot. If your not lucky like I was last time it could take days, beer and a lot of $&^% to get it threaded like it did mine. Also make sure the orientation is correct, IE not upside down.

deliriousga

I replaced the clutch master cylinder and now all is well. It has been holding up just fine for the last week as the daily driver.

FlyingDog

Did you look at your old Master cylinder to figure out what is wrong? Do you think it was the new master or the new blue hose that fixed it?

Mine is doing the same thing and I think BeerFish's Euro is now doing it also. I have no leaks. Bleeding improves it, but I never see any air come out.

I just got a new blue hose and a speed bleeder. I don't want to waste the effort of installing the blue hose if I'll have to do the master later, and of course I don't want to waste money on a master if I don't need it.

hupp

Success, good to hear!


.....AND ayone who says that replacing the door handle linkage is the rite of passage has not had the pleasere of replacing the clutch master....yet.