Clutch pedal has no feel and pushes to floor effortlessly; causes?

Hi guys

After driving on a highway for 40 mins at 90kmh the clutch pedal went straight to the floor, had zero feeling and I was unable to change gears. I checked the reservoir which was full however there was little to no movement on the slave cylinder. I assumed the fluid had boiled and sat the car for 20 mins. Feeling returned to the pedal with the engine off, but as soon as started it become quite soft again, which I assume was due to the power assist. Pushing it all the way to the floor I was able to select a gear and drive home.
Today the pedal is as soft as yesterday. I will replace the slave cylinder, rubber line, flush and bleed. Apart from this what else could lead to the above symptoms? Also, how do you check the clutch in a GB TB42; I'm told they don't show signs of slipping and just let go.

FYI - the car is off the road while I also try to resolve large coolant leaks.

Clutch booster may be leaking? But then again, it should just be extra heavy then. How close is the exhaust to the clutch lines and slave cylinder? Radiant heat will give you grief on the clutch too.

Master cylinder.

Yeah I would replace master and slave cylinders at the same time.

The master was done not all that long ago. The exhaust is very close to the slave on GQ's.
Annoyingly Repco sell the slave but not the rubber clutch line which seems only available online.

Was the master rebuilt or a new one, if rebuilt then recheck as there may be an internal problem

Quote:

---

Originally Posted by pearcey

Was the master rebuilt or a new one, if rebuilt then recheck as there may be an internal problem

---

New I believe; it was before I owned the vehicle. Perhaps 3 years old but only 15k.
I have to order half my parts online as they're not stocked here. I'm hoping to have everything by mid next week. Will start with a new slave and flush and bleed.

Sent from mTalk

Use a bleeder like this. Saves lot of trouble.

http://www.ebay.com.au/itm/Hand-Held...IAAOSwA3dYZiCZ

I see your location is Adelaide , where about`s , north, south,east or west. I`m down Christies way and spent 45 years on the tools in the brake and clutch game, so if your close enough I may be able to have a look.

Quote:

---

Originally Posted by dom14

Use a bleeder like this. Saves lot of trouble.

http://www.ebay.com.au/itm/Hand-Held...IAAOSwA3dYZiCZ

---

Thanks, i bought one a while ago in prep for the brake flush. Looking forward to finally using it.

Quote:

---

Originally Posted by pearcey

I see your location is Adelaide , where about`s , north, south,east or west. I`m down Christies way and spent 45 years on the tools in the brake and clutch game, so if your close enough I may be able to have a look.

---

Thank you for the offer however I am Semaphore way. If my order from Patrolapart ever turns up I'll swap out the slave and slave line and see what happens. I was under the impression the adjustment was on the slave/fork but i have just read it is fixed and done from behind the pedal; fingers crossed for a nice learning curve!

An update. Finally got around to replacing the slave cylinder (cooling system etc) to get car driveable and it felt allot better for a few weeks but not perfect. I have now adjusted the push rod on the pedal right up as the clutch was not engaging until close to full release.
The clutch now engages a bit sooner but not much. Before I book it in for a clutch I want to make sure its not the master cylinder or power assist.
I've heard they can leak back into the power booster but I don't seem to loose fluid. Could it also be simply by passing within the cylinder; what's the best way to test it?