I recently rebuilt all four of my calipers in my 1984 Porsche 928S. I filled up the reservoir and started on the back passenger side. I have speed bleeders on so cracked it about a quarter turn and pushed all the fluid through. I then did this on the rear driver side, front passenger side, then front driver side. I still am not getting pressure on the pedal at all. I also have a vacuum bleeder that I just went through in the same order on all four and still cannot get the pedal to show any pressure. Is there something that I am missing in the process on this car?

I appreciate any help you can give me.

 

Did you bleed the master?

 

if you went full stroke on an original master,
then you now need a new MC.

 

You might do well to purchase a pressure bleeder package if you are going to do this task yourself. Since I started using one a few years ago I find it so easy and trouble free.

 

Yes, I have used both vacuum and pressure bleeder, and have found the pressure bleeder most beneficial.

 

I also vote for the pressurebleeder. It can be a bit tricky to get all the air out of the system, but with some practice it should not be all that difficult. Maybe your mc is shot as Stan says...

 

On an old 928, if pressure bleeding, I'd recommend using the dry method. I used the wet method with mine and it overflowed the reservoir out the fluid level sensor portion. In my newer Porsches iv head no issue doing the wrt method and it's convenient to put 3 or 4 liters in and run around to the multiple cars.

 

So I tried everything to bleed both the master cylinder and the rest of the brakes. When I bleed the master cylinder fluid comes out and no bubbles but it does not seem to have much pressure. What is odd as I had the booster and master cylinder rebuilt a year ago and everything seemed to be working well last year before I did this rebuild. I had the master cylinder out of the car and when you press the plunger it seemed to easily build pressure. There was definitely at least light pressure every time I bled all the calipers also.

I've never had to bleed a whole system before that was dry so maybe I am doing something wrong.

I'm going to buy one of the pressure bleeders to give that a try. I appreciate everyone's input and help.

 

OK try this
you say you have a recently rebuilt MC ?
OK first open the B nuts that go to the MC one at a time , from the rear of the car to the front.
let each one drip till you dont see any more bubbles
Then move to the pressure valves .
( NOTE this is a gravity bleed .)
Once this is done.
Put the pressure bleeder on the tank pump it to 10 PSI
NOTE no fluid is in the pressure bleeder tank.

Then start at the LF then RF then LR then RR,
crack each bleeder till you see a steady stream of fluid.
Once this is done remove the pressure tank and press the pedal down,
you should have a pedal,
if you dont then press a few more times see if you are building pressure.
If not I suggest to remove the bolts on the MC slide it forward and verify that no fluid is leaking into the booster.
NOTE as an alternative you could remove the vacuum port from the booster then use a bore scope to view the rear side of the MC.
If its leaking then it needs to be replaced.

If you dont get any pedal then the chances are good the MC seals need to be replaced.

NOTE you should also have replaced the old rubber flex hoses with new SS flex hoses,
I suggest to only use ATE brake fluid.

 

I apologize for my ignorance, but what are the B nuts?

 

I believe he means bleeder nut since the following remark (in red).

 

B nuts are what hold the lines into the MC body , from the back to the front.
drip till no more air bubbles come out.

 

Got it! The power bleeder worked great. Oddly enough, there were no real bubbles. I hooked it up and pressurized the system at 15 psi. I let it sit for a few minutes to make sure there were no leaks and it held strong. Then bled each caliper and the master cylinder. Brakes are nice and tight. Thank you for the help!

 

FWIW I only suggest to use 10 PSI on pressurizing the motive tank as its possible to blow the MC tank out of its grommets,
especially if you used DC111 on the grommets to prevent the feed ports from corroding.

NOTE I also suggest to take an old piece of rubber seal molding like from an old hatch seal,
cut a piece about 6 inches long and place it on the fender edge above the MC cap inlet ,
this will reduce the amount of water that touches the MC .
NOTE when you wash the car water will rinse down onto the MC cap and then to the tank then to the grommets,
this is how the grommet inlet bores get rusted.

The DC 111 will prevent the water from touching the metal and thus stop the corrosion process,
the rubber strip will divert and reduce the amount of water that touches the cap and thus prevent water from getting into your MC tank.