Br3nn4n

Hi guys,

I'm not sure if I posted about my brake problem before, but since I bought the car I've had to constantly work on them and now have ZERO brakes. This is an 86 944 N/A.

I got the car with almost zero braking power, but still a little...enough to stop if you gave yourself several blocks at 45 MPH. The guy told me when I got it that it needed a seal, which I replaced and that stopped that leak from the booster to the Master Cylinder. Then I bled the brakes with a vacuum bleeder (Mityvac) and one of my bleeder valves broke off in the hole (though, it appears to be sealed so woot!). Still very little brakes.

Next, I went to try to bleed again, after putting teflon tape on each valve (well...the 3 I can unscrew anyway) and got a little better vacuum but still lots of air. I realized it was probably sucking air from the rubber seals from the spouts on the bottom of the brake reservoir going into the Master Cylinder. So, 2 days of waiting later my dealer got them in and I installed them. Bleed....still very little brakes.

Finally decided to whip out my pressure tester and found I have an adapter that fits the threads on the brake reservoir perfectly. Popped it on there, pumped to about 5 to 7 PSI pressure, and the car helpfully started pouring fluid out of the right front bleeder valve. Apparently that Maker's Mark hit me a little harder than expected last time I bled the brakes and I forgot to fully close that bleeder valve. And at this point, I had only about a quarter a reservoir of fluid and no more in my stash.

So I made sure that valve was closed and ran around bleeding again. Still getting a LOT of air, to the point where it would drain my vacuum of any vacuum in about 6 seconds. Made sure the reservoir never ran dry, though still it was at about 1/4 full. Also, when I pressurized the system, the BLUE line coming off the reservoir began weeping fluid slowly and dripping about one drip every 3 seconds. (I assume that's not supposed to happen?)

Any ideas what's going on with my system? I should have been able to pressurize it with no issues, right? I was thinking Master Cylinder, but there's no fluid coming from the weep hole, which would be a major indicator of a problem, yes?

Sorry for the long post but I figured I'd explain what I'd already done.

TL;DR: Bleed, bleed, bleed, replace seals, bleed, little brakes, pressurize, bleed (all air), NO brakes. ?

william_b_noble

yes, it should hold 10 psi, mine does. the blue hose is to the clutch slave. change it, it is a part of your problem. Bleed the clutch system too, don't forget. you may have seized calipers, but with a pressure bleeder, it shouldn't be that hard - vacuum bleeders just have never worked for me. I've pulled all 4 calipers and the clutch master/slave and the brake master off, changed them all or rebuilt them all and reinstalled and used about a quart of brake fluid total to refill and bleed. If you are getting a lot of air, something is seriously wrong - did you replace the master cylinder? have you rebuilt calipers?

Br3nn4n

Hi William, I haven't done anything with the calipers, nor any of the cylinders (rebuilt / replace). Funny enough, and I feel ridiculous for admitting this, but I got some fluid and filled up the reservoir and was able to bleed them using the vacuum just fine. It definitely was leaking air from those seals going into the brake MC, so that was part of my problem.

The clutch also works fine (always has), so I don't want to mess with that. I've heard it's pretty hard to bleed, but I can't see how with the vacuum. How hard is it, relatively speaking? I'd just rather not mess up something that's working fine, but it very likely has some air in there like the brakes did.

Now the blue hose: I think it's leaking from the hose itself, right where it connects to the reservoir. How expensive / hard is that to replace? I also noticed that the nipple the blue hose plugs onto is slightly cracked, which is also a source of air, but again I've never had any problems with the clutch. I might try plastic welding that nipple just to seal it up a little more so I don't have to buy a whole new reservoir. That blue hose leaking is a little worrisome; although it only does it under pressure from my tester.

MAGK944

First, you really should replace the reservoir and the blue hose as they are obviously trashed, both relatively cheap and easy to replace, under $100. Also if you are careful you shouldn't need to bleed the clutch if you are just changing those two items. Saying that though they are likely not part of the problem of air in the system as they are both before the clutch and brake master cylinders.

If you are not seeing any fluid leaks at your calipers with the system pressurized your problem is likely the seals inside the brake master cylinder are worn. It's a common problem and again not too difficult or expensive to repair. It could in theory also be an internal fault in your power brake vacuum canister but they are not a common failure. I would just get a new brake master cylinder rather than rebuilding it, not much to save and a lot more hassle to rebuild with a seal kit. Again you shouldn't have to bleed your clutch if when replacing the brake master, only the brakes.

However, bleeding out all the old fluid in both the clutch and the brakes is recommended, so doing it all at the same time makes sense. Clutch bleeding isn't too bad a job, just need to raise the rear of the car quite high to be effective. It should be quite easy really as you will not have touched any components in the clutch hydraulic system so there shouldn't be any air locks introduced to deal with. Good Luck!

Dougs951S

Buy a motive power bleeder. I have a tool box full of specialty Porsche tools and my motive is far and away the best specialty tool I own.

Br3nn4n

I may make my own since I already invested in the pressure tester. Heck, I could do basically the same thing by just refilling the reservoir after each wheel.

william_b_noble

ok, BR3 - imagine that I'm screaming at you -

You must change the fluid in all of the hydraulic system, ASAP - the fluid is hydrophobic, it will cause corrosion - Porsche recommends changing every other year, if you do this the master cylinders and whatnot last for over a decade, if you don't they fail much sooner. I bought my 85 new, and I've replaced the master cyl once, and the clutch cylinders once. The fluid you bleed out will be black with crud, and it is that crud that causes trouble.

Br3nn4n

ALRIGHT I WILL, WILL. (I'm Brennan, by the way. )

To be honest, this car basically has had its flush. I got it with no fluid and have since flushed so much damn fluid through it trying to fix leak after leak that it comes out quite clear.

I still have to fix a broken off bleeder valve (that should be fun) on the front left wheel, then I will aim for flushing and filling with good DOT 4. At least now I am ABLE to bleed without just making things worse. When I swap fluid...just suck the old out at the reservoir, refill with new (Super Blue would be nice), and bleed wheels then clutch. Correct?

Oh...and not to be a dick...you meant hydroscopic I believe? Phobic would be repelling of water, which brake fluid loves. [/dick mode]

StoogeMoe

Don't put teflon tape on the bleeders. Calipers get very hot, and will melt that tape making removal difficult or almost impossible. I'm not sure what you mean by no brakes. Do you have a firm pedal and nothing happens or is it going to the floor? You need to address that caliper where the bleeder broke off. If you have air in the system, you will need to bleed that caliper. You are doing the bleeding in the right sequence right? From the sound of it, you may be looking into rebuilding the calipers also. I'm sure the seals in there are shot as well and you have a lot of crud behind the pistons.

turboS_swede

You can also "bleed" the caliper with the broken screw by cracking the brake line fitting. However I would highly recommend fixing/replacing that caliper so you can properly bleed the system and ensure the calipers are working properly.