84 944 Clutch not working properly
 

I am posting this for my father, so keep in mind that I don't know how to describe everything in perfect detail.

He has a 1984 944. About two years ago he went out to the car one morning and the clutch was on the floor. The clutch slave cylinder had died. It was brought in to a mechanic who replaced the master and slave clutch cylinder. Everything was fine until...

Last week he went out to the car, got two miles from home and the clutch pedal went to the floor. However, the different part of this is that he could pull the clutch pedal back up, and it then worked normally for a while, when it did it again.

After bringing it home, we both looked at it, and you can pump the clutch in and out many times, then it will suck itself to the floor. It's almost like it is spring loaded to the floor. So, he had me look around at everything. There are no leaks, or signs of leaking anywhere along the lines or at either of the cylinders. There is a preload spring for the clutch, which also looks fine. The fluid level in the reservoir is fine. We bled the entire system the other day, and there is no air (there wasn't before either).

The thing with sucking itself to the floor is that it isn't even constant. I was in the car pumping it trying to make it fail, and occasionally I could actually make the clutch almost "drop" into the halfway engaged position, too.

I can answer more questions if I get them, or ask him, but we are at a loss for why this would be happening (especially given that it doesn't happen every time or even often).

Thanks in advance...

try pumping the petal and bleeding the system at the junction in the line behind the engine up high on the firewall, this is the highest point in the system and air can stay up there when you bleed the system at the slave cylinder.

Pull the carpet back in the floor where the clutch rod goes through the fire wall. Look for brake fluid between the carpent and the floor. Many "new" clutch masters are failing.

Also check that you have fluid in the brake reservior. The back half feeds the clutch as well as part of the brakes.

The reservoir is full.

There is no leak behind the carpet for the master cylinder.

This leaves it to be either air in the system at the master cylinder, or another problem.

When you talk about bleeding the system in the line up high on the firewall, are you talking about the braided rubber line that goes to the reservoir and into the firewall, or the metal line that runs from the back of the master cylinder?

the metal line. i think it's where it turns to a rubber hose that goes straight down to the slave.

Wouldn't using a pressure bleeder blow any of the air through and come out through the slave cylinder?

Sometimes. Fluid flows down; bubbles float up. So you have to push the brake fluid through faster down than the bubbles go up.

I bleed the clutch master where the line going to the slave comes out the end.

try that.. but what I've learned is that just because you bought a "new" master/slave, doesn't mean that the parts themselves are "new".. they've sit on shelves for years before they're sold and are considered to be called "new old stock"..

if the bleeding doesn't work, it may be time to buy another master/slave..

Local 944 driver has gone through two clutch masters in the last two years. Now working on the third.

+1 on bleeding the line. It's the easiest option and might be it. And it makes sense if the pedal sticks sometimes...it just means your master an/or slave cyl is on the way out (as opposed to completly dead)

Tried bleeding the master clutch cylinder.... no success.

Any other ideas?

my car was doing the same thing. you could put your foot under it and lift and pump it a couple of times and it would work. if i drove a long distance without using the clutch the next time i pushed it in it would stay halfway down. i pumped the pedal two or three times and cracked the line up high behind the engine and there was air there. if i would try to adjust the pedal it would pump up tight and take out all the freeplay. also make sure there are no holes in the supply hose from the m/c reservoir, and that the brake fluid level is over the top end of the hose.

hmmm, just been thru this scenario. clutch pedal near to floor, but can disengage/select gear. reservoir is full, no leaks internally/externally. bleeeding clutch produces no result. fit new master/slave/hoses. no result. on closer inspection {i should have tried this first!!} as the clutch pedal was being pumped, i was looking at the master cylinder, which was moving, actually pivoting across one bolt. seems my firewall has cracked at this point, and apparently its a common problem for the early cars. as the pedal moves, the master also moves, not the actuating rod/internal seal, and this shows up as lost motion/broken leg syndrome!. check to see if your master cylinder is moving as the clutch pedal is pushed in. if it is, then you will need to weld in a plate to strenghen this area.
i have made up a bracket, that holds the master body tightly, and its anchored to the body, so it cant move side to side, or back to front. voila, my clutch is like new again, or at least its working, and will do fine until later in the year when i can do the proper repair.
i seriously hope this is not your problem.
good luck.
bob.

Bob, raises a very good point. The firewalls can fracture more than you would care to hear about.

Would I notice actual physical movement when looking at the master from the engine bay?

If so, then that's not the problem.

replacement...
I fought it for a very long time, but this was my final outcome and I couldn't be happier.

Yes, you should be able to see it move if that is the problem.

I'd replace the slave first. If that didn't get it I'd do the master. Slaves on some cars don't seem to last more than a couple of years - less if the rear oil seal leaks.

if there is no movement, at the master, then thats good, trust me ! i had about 3/8" movement, as the master cylinder moved over against the brake servo. i guess one bolt has pulled thru the thin sheet metal, and when the clutch pedal is pushed in/brass actuating rod tries to move the plunger inside the master, then the easiest thing to move lets go=master cylinder.
there is not much to go wrong with the clutch actuating system. only hoses to check, and possibly a new master/slave combo. bleed the system correctly, and you are good to go !
one last thought. the brass actuating rod. where it screws into the small block attached to the clutch lever. can i assume that its almost screwed all the way out of the block? if it is, then i may have the answer for you.
bob.

More work has been done since last time, we took out the master cylinder and took it apart, operation of that seems fine. Rebled the system again after it was reinstalled.

Any more thoughts?