Brakes not releasing pressure. 1980

[mixybro4]

I have replaced the M/C, all 4 calipers, all the rubber hoses, and removed the proportioning valves. Yet they still don't release pressure after you drive for awhile.

[Mrmerlin]

what fluid di you use ATE super blue or ATE Gold
/
What was the condition of the MC new /used?

try unhooking the booster line,
and plug the hose,
yes run without boost assist ,
you may need a new booster

[mixybro4]

I just used regular oriellys brand dot 3 I believe. I did run it with the line plugged and unhooked. It did not seem to solve the problem. The M/C was brand new and I took it off to make sure it was properly installed. And then put it back on. I came to the conclusion that it was the proportioning valves. So I removed those. Still did not fix the problem. Anyway it could have been a falty master cylinder? I'm really pissed because this is the one thing from stopping me from driving it.

[mixybro4]

Any ideas?

[Mrmerlin]

where did you get this MC and why not use ATE brake fluid in a brand new part

[mixybro4]

Some mechanic bought it for me I'm not sure where he got it. I've never heard of ATE?

[neil30076]

Originally Posted by mixybro4

Some mechanic bought it for me I'm not sure where he got it. I've never heard of ATE?

For ATE info, check out:
ATE -*ATE Brake Fluid

Some mechanic !!!! Is he a Porsche 928 expert or a " all european cars worked on expert".

If that part came from CardOne or a chinese owned shop in LA that rebuilds them - toss it and get the right part - they are junk. Listen to Stan (Mrmerlin) - you will never get this solved by just trial and error...

[mixybro4]

Some European car mechanic. Biggest mistake I ever made. Found a really nice 928 speciallist close by and he helps me out with a lot of stuff. I'll find out where the M/C came from. Should one drip fluid when it's just sitting on the bench? I noticed this one doing that, and Oreillys said it was normal.

[neil30076]

Originally Posted by mixybro4

Some European car mechanic. Biggest mistake I ever made. Found a really nice 928 speciallist close by and he helps me out with a lot of stuff. I'll find out where the M/C came from. Should one drip fluid when it's just sitting on the bench? I noticed this one doing that, and Oreillys said it was normal.

Yes, if there is fluid in the m/c it will drip out on the bench.

[mixybro4]

Guy said M/C was ATE brand and they got it from a supplier called worldpac?

[honerboys]

loosen the wheel lines at the master - if fluid drips out and the brakes release then the master might be suspect - it could also be the pushrod from the pedal is out of adjustment and is too long and not allowing the m/c piston to retract enough to release the pressure

[mixybro4]

I adjusted the push rod all the way so it has tons of play in the petal to see if that was the problem. Did not solve it.

[neil30076]

Did you re-install the proportioning valves? Without them you will never get the correct brake operation, You do have the WSM's? Vol 4, Section 47 is your friend right now.

[mixybro4]

No I got rid of them I believe. It was doing this before I got rid of them.

[mixybro4]

I do not have the workshop manuals. Still have to purchase those

[Mrmerlin]

there is another adjustment though not usually used.

before you touch it
loosen the nuts that hold the MC to the booster
and remove and plug the vacuum line,

drive the car see if the brakes are still sticking

the adjuster is inside the booster but like Ii sai d this isnt usually adjusted.

World pack is where Roger gets his parts so you should have gotten a good part
I would only use ATE gold or Blue fluid in a brand new MC

[stepson]

Originally Posted by mixybro4

No I got rid of them I believe. It was doing this before I got rid of them.

Damn! I would've liked to have that valve.