WolfeMacleod

I'm working on getting this thing roadworthy again. It now runs well. New windshield install due on the 25th.

Car was parked since 2011.

It's been driven a few times over the last week or so. Today a new problem popped up with the clutch.
Pedal goes halfway to floor before giving resistance. Does not want to return smoothly. It "pops" back up. Before today, it felt normal.
Clutch starts to grab immediately when releasing.

During repairs a couple months ago, the brake master cylinder was replaced. System bled and fluid replaced.

I don't know how interconnected the brake fluid and clutch systems are. Fluid level in reservoir is normal.

At 120,000 miles, a new clutch was put in (in 2008). Car now has 123,000 and change.

Should I be looking at the clutch master or slave?

Starting to get nervous I might not be be to make the windshield appointment on the 25th...

Otto Mechanic

I'd start with the slave, it's easier to bleed. It does sound like air got in there somehow, possibly a leak.

Otto Mechanic

My recollection (from my experience with a 931 in 1989) is the systems are completely connected; the brakes and the clutch use the same fluid.

No Lag

If it like the 944 and it probably is the fuild is connected. The clutch is tricky to bleed too, so maybe it needs further bleeding? The trick on my S2 was to lift the back end up and bleed again. I used a power bleeder. Finally after a couple of tries all the air was out and a firm pedal.

WolfeMacleod

Pedal was firm before today, seemed pretty normal.

I have the Motive power bleeder. I'll have to look around for instructions on bleeding the clutch. Clarks maybe?

Was just quoted $953 for clutch master and slave replacement. Considering my new-to-me 968 goes in for $4000 worth of service next week (same day as 924 windshield install) ouch.

Otto Mechanic

If you use a Motive it isn't complicated but it may not work well either. I just went through this with my 944S2 after a brake/clutch rebuild. It is a good idea to lift the rear of the car when you're bleeding the slave, but some will argue you're better off pushing fluid through the system from below at the slave nipple. I've never done it but I understand it takes putting a fluid supply on the slave cylinder nipple (a squeeze bottle full of fluid), taking the cap off the reservoir, and forcing fluid up through the system into the reservoir.

I was able to bleed the air out just using the motive and lifting the back of the car. It took time and a lot of fluid, but it beats replacing the master and slave needlessly.

WolfeMacleod

I just did a "brake pumping" style test. Pumping about 20 or so times, and the clutch pedal feels pretty normal again, and doesn't sink so low. Pedal return is more normal.
Air in the line?

Otto Mechanic

Somewhere I'd guess. It's always a crap shoot when you replace the Master cylinder, even if it's bench bled it can have air in it that migrates over time.

You may be able to call the folks that did it and ask them to bleed it again for free, but if you already have a Motive you may as well do it yourself, probably less hassle and almost guaranteed to improve your relationship with them

Otto Mechanic

I should also mention that after lifting the rear of the car and bleeding the slave, you should perform a full bleed of the brake system again to remove any air that migrated from the slave into the rear brake lines. Repeat until there's no air in the slave or the brakes.

I went through about 3 liters of ATE Blue during this process. I cut corners a bit and recovered the fluid and re-used it. I know you aren't supposed to do that but if it's clean fresh fluid and you're careful about keeping all the containers you use clean and free of contamination (either water or old fluid) I think it's worth the risk.

In this application, isopropyl alcohol. 90% or better, as a cleaning agent for your containers, will also be your friend.

Otto Mechanic

I'll also add a gratuitous (and uninvited) plug for my campaign against the new DOT regulations making blue (or any color other than yellow) brake fluid illegal in the US.

It makes this process wasteful since no one can really know they've completely flushed the hydraulic system unless there's a color change. We end up wasting fluid, which isn't all that toxic but it isn't good either, and we also compromise the safety of our cars.

Write your congresscritter and demand this stupid regulation be repealed.

Bring Back Blue!

Damnit.

WolfeMacleod

Was done by a Pelican tech writer who stayed here for a week, helping to get the car back into running order as far as the timing belt and braking system were concerned (brakes were froze solid) But we didn't bleed the clutch system, as it felt fine when the master brakes cyl was finished.

YES ON BLUE!

Otto Mechanic

Well, I'd say that's a big clue. Definitely bleed the clutch (and bleed the brakes again) before you shell out almost $1000 for a new Master/Slave and end up with exactly the same problem?

Go Blue!

WolfeMacleod

After sitting overnight unused, the clutch pedal again did the same thing as it did yesterday. Pumping it again returned it to a normal feel.

jvandyke

it's the master, IMHO
Just had this on our '87 924s. Is there any fluid at all at the pedal push rod where it connects with the master (at the firewall)?
A couple weeks ago my kid (who drives the car) asked me to take it for ride, I was stunned that the pedal wouldn't come back up and it only engaged the last 1/2" I immediately grounded the car and we did a master. Totally solved it, pedal engages normally and comes back up as it should. It was the easiest master cylinder swap I've ever done (I usually work on quirky small cars though with master crammed in tight places, this one was a walk in the park!)
The inside bore probably started to pit and corrode from sitting unused, when put back into service it began to wear on the seals and they are now "soft failing". It will go completely dead soon. I couldn't find rebuild kits so just bought another, $75 or so.
While brake and clutch pull from the same reservoir, the clutch side shouldn't suddenly need a bleed unless something is failing and even then bleeding is a temporary "fix" if any.
oh and
GO BLUE
(not a great season though, Penn State just paid us back for last year...ouch)

WolfeMacleod

Appears dry as a bone.