Worked on his 240D which has a similar hydraulics set-up to 928...no power bleeder, had to make a road repair after loosing clutch line.


Attach rubber jumper hose from slave bleed nipple to closest brake bleed nipple.

Open nipples.

Stroke brake pedal to reverse-bleed clutch.

Close nipples.

Drive on.

 

What a brilliant idea - from someone who has bled the clutch curcuit (from Dry) by the side of the road with a 928 supported on it's own weak aluminium jack.

 

This method works great!!!!

Finally got my clutch to work proper after re & re

Kudo's to Landseer (Chris) for sharing; tell you dad thanks

Ken
PS I know its 6 months later, but peeps kneed to know!

 

I don't get it. How does it work?

 

It works by reverse bleeding the fluid UP from the slave rather than down from the master; It also wastes very little fluid as the air is let out back up at the reservior.

When you pump the brake pedal, it pressurizes the brake circuit. Since you have opened the bleed screw for the brake, the pressure pushes the fluid out through the jumper hose INTO the clutch slave, and backwards up through the clutch master, to reservoir. Since air wants to rise, it is much easier to purge the bubbles this way.

This is one of those Homer Simpson Duh-OH! moments.

So simple, even a caveman could do it.

Ken

 

He's using the breaks as a power bleeder.....brilliant!

 

Does the break pleeding nipple needs to be closed once the pedal hits the floor ?

 

I didn't play with my nipples, ( I save that for when I'm alone in a dark room....but I digress) just pumped a few dozen times. The fluid circuit is closed in this case, so all you are doing is moved fluid from the res. down through the brake circuit, out the jumper to the clutch circuit through the slave up through the master, returning to the reservoir, where the bubbles can work their way out of the fluid.

If you have a lot of air (ie just after a re & re) you''l want to keep an eye on fluid level so you don't just cycle more air through, and pooch your brake AND clutch.

The beauty of this is that its a one-person job, and you don't have to keep going back & forth. This is a method that should be stickied under a "10 best solutions to common 928 headaches"

Ken
PS I have the pressure bleeder from 928intl, and while it is great for brakes I did not find it to be a cure for clutch-bleeding woes. A pressure bleeder that pushes UP, now that might be the fix, but I'll stick with this one for now.

 

I wish I can see a drawing/picture of this. It is still a little fuzzy to me.

 

So simple it has to work.
I'd purge the jumper with a few pumps before sticking it on the slave nipple to avoid having to add more air before the fluid starts to flow into the slave...

 

Heres a couple of (lousy) pics that I hope illustrate the idea.

Here's the layout


And here's the flow:


And yes aggravation, connect hose to brake bleeder first, let fill with fluid, then connect to clutch slave nipple to minimize introducing air. In my case, gravity took care of filling the hose, so I didn't have to pump for that part

HTH
Ken
PS I don't know how long the jumper hose *should* be; I had a 3ft hose at hand, and that was more than enough
PPS at no point during this operation should you touch the clutch pedal- LEAVE IT ALONE until you have closed the bleeders

 

I'm getting ready to replace the blue hose and stumbled across this thread. Didn't pick up much traction when introduced I was wondering what others thoughts were on this trick

 

Reverse bleeding works, for some reason I thought it was in the WSM. Years ago when I watched someone bleed a 928 clutch for the first time, that's how he did it.

The only issue I ever had with this method was a slave nipple with slightly loose threads. Pumping the fluid in came right out the threads. I've only ran into this once, on my own car.

 

One of the problems I've had is air trapped in the clutch master.

When mounted in the car, and with car at any safe orientation, the firewall-contacting part of master cylinder is always higher than the front.

I wish there was a bleed screw on the master at its highest point, plus a access port cut in through the firewall to access it from the pedal area. I might cut one and thread a nipple into the master. Right now the only way I can get the system bled is by unclipping and releasing piston in the clutch master so that air and a bit of fluid is released through the firewall.

The pressure bleed doesn't work for me, forward or back. Maybe if the clutch pedal was on the floor, then system pressurized from the reservoir, then the pedal lifted slowly from the floor....

 

Interesting. Keeper.