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Posted by: terrymason Sep 19 2006, 07:07 PM

a couple of days ago my front brakes ran out of fluid - I did some inspecting, and I belive that my passenger caliper is bad. I've replaced the caliper, and went about bleeding it, but I can't get fluid in the lines.

I've taken the caliper off again, and am simply trying to get brake fluid out of the end of the brake line, just before the caliper.

I've tried both pumping the brakes and using a vacum bleeder, and can't get and fluid out of the line. The level of the resovior never drops.

So what is it? I'm assuming that there isn't a leak, could I have a bad master cylinder? Do I need to somehow prime this thing?

Posted by: bd1308 Sep 19 2006, 07:10 PM

Shoudlnt have to--I ran out of fluid three times when I was rebuilding the brakes, and I simply poured more fluid in and pumped the brakes to get fluid back in the lines, and then did a four point bleeding.

Maybe your MC is bad?

b

Posted by: terrymason Sep 19 2006, 07:21 PM

That's what I'm thinking.

The way it stands now, I've removed the passenger front caliper and pretty much just have a hard line from the MC to the passenger wheel well. I should be shooting fluid all over the place everytime I pump the brakes.

Posted by: URY914 Sep 19 2006, 08:25 PM

Do you feel resistance against the pedal as you pump it?

Try bleeding the caliper on the driver side. See if you get B/F out of that one.

Posted by: Brew Sep 19 2006, 08:27 PM

Or blockage in the line.(Hey, it could happen!) Does your D-side caliper work?

Posted by: terrymason Sep 19 2006, 08:35 PM

no pedal at all - it'll hit the floor just using my hand to press the pedal. I'm guessing that if I had only rear brakes I should still be able to pump them up right?

Posted by: terrymason Sep 19 2006, 08:37 PM

I'll take the driver side off tomorrow and test, but I'm thinking that I've got a bad master cylinder

Posted by: Brew Sep 19 2006, 08:42 PM

Kinda sounds like it, but I cant see why you wouldnt be able to get fluid out with a vacuum pump?

Posted by: Hammy Sep 19 2006, 09:45 PM

Posted by: terrymason Sep 20 2006, 07:01 AM

slightly off topic - I'm looking to replace the master cylinder with a 19mm. Anyone know what year these were in the 911s? I was looking to buy local, but don't know exactly what to ask for.

Posted by: Brew Sep 20 2006, 07:18 AM

Go to the Pelican page, the P/N is easy to find. Have your local guy cross reference it.

Posted by: terrymason Sep 20 2006, 07:20 AM

doh!

Thanks, that was easy enough.

I'm just going to upgrade to a 19mm master cylinder anyway - thanks for the help guys.

Posted by: type47 Sep 20 2006, 07:21 AM

how old are or are your flexible rubber lines original? i've read that they swell and obstruct fluid if/when old. possibly the fault?

Posted by: ws91420 Sep 20 2006, 07:21 AM

Porsche part # for 19mm MC is 901 355 012 00

Posted by: terrymason Sep 20 2006, 07:23 AM

yeah, that's possible and I'll replace them too, but I can't get over the fact that if I pump the brakes 20 or 30 times, the fluid level in the master cylinder never moves, and fluid never makes it out of the brake line (from the disconnected caliper)

Posted by: URY914 Sep 20 2006, 07:53 AM

Are you SURE that the pedal rod is pushing on the M/C? There is a piece (the rod) that rotates on the pedal that actually presses on the M/C to pressurize the system.

Somethin' ain't right here.

Posted by: MattR Sep 20 2006, 08:43 AM

I replaced a caliper on my 912 a while back, and when it came time to bleed I had some strange problems. I ended up buying a master cylinder and the bleeding problems went away. Thats a pretty poor troubleshoot, but when all else fails, buy a mastercylinder... hah.

Posted by: bondo Sep 20 2006, 02:26 PM

If the piston is not returning fully against the stop (circilip and washer in the bore) the holes that allow fluid in from the reservoir will not get uncovered, and the master cylinder won't be able to get any fluid. This can happen from bad actuating rod adjustment, a sticking piston, or a weak return spring.

Posted by: alpha434 Sep 20 2006, 02:51 PM

Where do you go to get a seal kit for the 914 m.c.?

Posted by: George H. Sep 20 2006, 03:07 PM

pelican has them NLA for 17mm instock for 19 mm

Posted by: t collins Sep 20 2006, 03:23 PM

I have seen collapsed rubber lines that would not allow brake fluid to flow through them and going to a 19mm master cylinder will not correct this situation.
Remove the rubber brake hose and try to blow air through it, that will tell you if that's it or not.
Good luck !
Tom

Posted by: JPB Sep 20 2006, 04:05 PM

Hey bro, sorry to hear of your problem but it sounds pretty symple. If your MC does not have a full stroke, it won't pump fluid. If the rod pushing on the backside of the MC is to long and needs to be screwed back a little or it won't do a thing. If this is a new or replacement part from another car, that is the first thing that needs to be looked at; then the lines not dripping ect...... Sometimes, you will just have the back breaks bleed and not the front ones; thats the same push rod adjustment and usually not the MC being bad.


Gluck!

Posted by: pete-stevers Sep 20 2006, 04:07 PM

eric sells all you need for your brakes.....

Posted by: Heeltoe914 Sep 20 2006, 04:17 PM

Make sure you do not pump the padel to the floor. Go about 50-70% down and up again. If you work it to the floor over and over you can rip the seal inside.

Posted by: terrymason Sep 27 2006, 12:44 PM

I've been fighting this thing, and will end up replacing most of the front brakes. I've put on rebuilt calipers, and am installing a new 19mm master cylinder, and will order some new rubber hoses - I'm starting to feel good about my brakes.

I did notice when I took the old master cylinder off, that the wire / electrical connection to the master cylinder had been taken off and taped up with duct tape. My understanding is that this wire alerts you to a loss of pressure in the master cylinder - is that about right?

My guess is that the master cylinder acted up some time ago, but since the brakes still worked somewhat, the guy just taped the connection up.

Posted by: joefri187 Sep 27 2006, 04:54 PM

I had the exact same thing happen on my 76. I could pump the pedal all day long and not bleed the lines. Took me forever to figure it out, but I wasn't the master cylinder, lines or calipers. It turned out to be a bad pressure regulator, the thing that is attached to the rear firewall that goes to the rear brakes.

There cheap at a wrecking yard and easy to replace. I would try that before you tear the rest of your car apart.

Good Luck!

Posted by: URY914 Sep 27 2006, 05:21 PM

That is called the brake proptioning valve.

Posted by: terrymason Sep 27 2006, 07:13 PM

NO NO... Stop!

I'll replace the calipers, hoses and master cylinder and see if that fixes it. If it doesn't then I'll move on to the prop. valve