curt_928

Hello everyone!

Just finished installing new clutch master cylinder and brake master.. in my 79' and thought the fun was over... only when I'm trying to bleed the Clutch system.. the clutch pedal just goes **Thunk*** on the firewall. Doesn't seem to be building pressure... Not sure if its air in the system that's not completely purging..

Any advice would be greatly appreciated!

Curt
79' in charleston SC

hacker-pschorr

I will never bleed a 928 clutch without one of these:

https://www.928gt.com/p-16-brake-pre...r-bleeder.aspx

Ben Allison

It's always a nightmare.

a few quick tips:

1) don't let the clutch/brake fluid get too low, or you'll introduce more air
2) The fitting near the driver's side "frame rail" (flexible hose to hard hose connector) is a good place to bleed when the system is still empty.
3) jacking the car in a variety of ways will help move the air bubble. I find it's easiest to bleed when jacked at the front passenger side.
4) removing the slave cylinder and pushing in the rod (with the brake fluid cap off) helps immensely.
5) make sure the clutch pedal is properly adjusted for the new master cylinder. If the master cylinder cannot retract enough, it won't allow fluid to flow into the system.

Good Luck it's tough.

hacker-pschorr

Unless you use a power bleeder. Once the car is up in the air / wheels off it takes less than 15 minutes to do the clutch and brakes.

curt_928

Thanks Guys!

Mrmerlin

Hey Curt just curious what color your car is? Light Blue with black leather? To fix the clutch there are a few wayssince you already have the cluch system installed try getting a oil pump can then fill it with clean brake fluid, open the bleeder on the slave and connect the oil pump to the slave gently pump the fluid back into the slave have a helper watch the master resivour so it doesnt over fill.
The next way is to get a pressure bleeder, and with about 14 psi or less connect the bleeder to mater resivour , and then open the clutch bleeder and let fluid come out for about 3 seconds then close the bleeder. wait for a about 20 seconds( the reason for this is that the Clutch resivour is small and it takes time for the fluid to refill into the clutch portion of the resivour)Then open the bleeder again. Either one of these ways will wind up taking a bit of fluid to try to remove the air.

Now the best way is to remove the master cylinder and the clutch slave as a whole unit from the car . This entails disconnecting the battery removing the starter and the hold downs on the oil pan and the sway bar and the blue hose connection from the resivour. If you do it this wat you will esentially be bleeding the system on the bench and then you will be getting most if not all of the air out of the lines. Set the master in a vise support the slave so its higher than the master , with your oil can pump connected to the blue hose pump till no air comes out of the bleederit wont take long to do this once no more air is present close the bleeder then plug the blue line with a spare bolt.
Install the master cylinder then the slave then the line securing bolts then the starter connect the blue line to the resivour. fill the resivour test your work you should have a hi and hard pedal, i suggest to use either ATE super blue racing fluid or Castrol brake fluid dont use any of the synthetic blends they seem to swell the seals over time and this causes other problems. Goodluck, you can also do a search for how to bleed the clutch you may see another writeup . The last way I told you about will save you time in the long run from the bleeding proceedure, as its nearly impossible to remove the air from the lines since the line has so many bends.

karl ruiter

The power bleeder helps a lot, but I often find I need to burp the master to get things to work right. In fact, my standard procedure now it to power bleed just until I see the bubbles stop and then burp. I don't even bother checking to see if it needs it. You can find threads here that describe the burping process.

largecar379

did you replace the clutch slave cylinder as well as the blue line and the flexible line (from frame to hard line)?????

if you didn't, you should---always my recommendation.

You did the hard part, now do the rest.......

Good luck!!!

--Russ

shmark

Enzo,
Love the reference and that bleeder is now on my Christmas list. So can you run through your process? Brakes first, then clutch, which ones, etc.? I need to do this too, and having a quick primer is great. I've always used speedbleeders in the past, but that's still something of a pain and the cost is comparable to the power bleeder. Thanks.

curt_928

I went online and got the power bleeder.. should get to me by wednesday.. can't wait to try it.. :-)

The car was once light blue with black leather... have since painted it silver.. though I need to find a place down here that can paint it.. bought it in maryland in 97'. refuse to sell it.. promised her a complete rebuild one day.. that day started this last july. Want showroom condition.. Am *kinda* regretting replacing everything but that will pass when the clutch is back and snappier than before.

Again, thanks everyone!

-Curt
now to look for burping...

hacker-pschorr

I've bled the clutch many times independant of the brakes and visa versa, I don't think it matters.

When I did the jobs together I do the clutch last. Right or wrong it's how I did it. Spring I'm due for both jobs on the 928's (once every two years, more for the track car).

With the clutch job I usually have a helper opening / closing the slave valve just like you would "the old fashion way" with the power bleeder attached. Not sure if this is necessary, works for me.

Curt,
If you are going to replace the blue hose (you should) put hose clamps on both ends. The factory did not - this line poping off will ruin your day.


#1 PIA with this system is the gravity fed master. Try blowing through a clutch master sometime - not easy. Now try to imagine thick brake fluid trying to willingly fill the master during a bleed process. This is where the 10+ psi from the power bleeder comes in. If you clamp the blue hose you can crank up the power bleeder.

largecar379

when bleeding the system, I (and Porsche recommends) start at the furthest brake, right rear, and work forward- then do the clutch.

power bleeder is a must---best money I've spent in years.

--Russ

Mrmerlin

dont over do the power bleeder pressure i blew a resivour of the master with just 20 psi, I recommend 14 psi or less, brake fluid goes everywhere,

85fortheDrive

14-15 PSI is fine.


Get a pal to sit in the driver's seat.
Connect bleeder to reservoir and pump to 14 psi. Make sure bleeder cap is fitted correctly onto reservoir opening.
Carefully loosen bleeder valve on slave cylinder.
I allow 10-20 mL of fluid to push through - heck, it's cheap.
The final burp is key...
Open bleeder valve and have pal push pedal down. It may stay down at this point.
Close valve and have pal get clutch pedal back to up position.
Repeat this a couple of times, noting how much burping air remains in the fluid evacuating from the slave nipple.

Once you've burped it a few times, you should have a firm clutch pedal.

And forgive me for having to say this, but watcha da splashing of the fluid when you taking offa da bleeder. It not good for da paint!

PM me if you'd like more help. BTDT and have Enzo to thank for his patience and help with me.

928FIXER

You can bleed a clutch master/slave cylinder job in 3 to 5 minutes.You just have to put the new fluid in from the bottom bleeder nipple on the clutch slave and it chases all the air out the top.