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Discussion Starter #1 (Edited)
Long story short...recently purchased 87 Spider Graduate, decided to replace all rubber brake lines, after replacement discovered leaking master cylinder during line bleeding, bought and replaced master cylinder from IAP along with a new rubber seal, bled all lines to "no bubbles", have no brakes! Pedal goes all the way to floor with motor on or off.

Bleeding procedure: did front and rear at same time passenger side first, did front and rear at same time drivers side next. I assume my assistant held pedal down on last stroke as I tightened bleeders because I instructed them to do so.

Could this be a booster issue? I had boost prior to replacing the lines or have I overlooked something during the procedure? Is there a simple way to detect boost? TIA.

Checked the manual again and found they say to use a sealer/adhesive on the mating surfaces to the servo unit. I was not aware of this...could this be the culprit? If so, any recommendations on a product to do this?

Mike
 

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Doubt it is a booster problem. Lack of boost would give you a very hard pedal, not 'no pedal'.

Are the pads in contact with the rotors? If you've pushed the pistons back into the calipers (like to replace the pads) then it can take a few presses to push all the pads out and into contact with the rotors before the pedal will act normally.

Try cracking a line at the master cylinder (loosen but do not remove) while your trusted assistant is pressing down on the pedal. Hold a rag around the loosened fitting and check for a squirt of brake fluid (brake fluid is a good paint remover - if any gets on a painted surface wash it off quickly). Do that for all the lines at the master (I think there is one for each front caliper and a third that goes to the rear axle.) If you get a squirt of fluid out each loosened fitting then re-bleed at each caliper (they are installed with the bleeder upper most, right?)

If you don't get a squirt out of the fitting at the master cylinder then there is a fault with the master cylinder.

BTW, the way to test for brake booster function (once you do get a functioning brake system/working pedal) is to pump the pedal 5-6 times with the engine off (this bleeds off any residual vacuum in the booster). Then, pressing down on the brake pedal, start the motor. When the engine starts you should notice the pedal moving down a bit as engine vacuum is applied to the booster. Before you condemn the booster check the one-way valve that is screwed into the intake plenum and the hose between the intake and the booster. If the one-way valve is stuck closed carb cleaner spray can usually free it up. If the hose is collapsed or leaking replace it.
 

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Discussion Starter #3
Thanks Eric, but wouldn't the fact that I was able to bleed all four calipers ensure that fluid was passing through the master cylinder? I did not replace pads so there was no piston movement, just new rubber lines. Also checked all connections for leaks, none seen. I will inspect that valve. Have you heard of sealant/adhesive being used between the master cylinder and servo? I did not have to do this way back when on my 72 GTV.
 

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I've not heard of an adhesive/sealant between the master & booster. I certainly didn't see that note in the manual when I R/R the master in our '84 for a rebuild.

Yeah, I assumed that getting fluid out during bleeding would indicate the master was pushing fluid. I confess to being stumped.

If you rapidly pump the pedal do you get any braking action at all? If so, that would indicate there is still air in the lines.

A low pedal was discussed here a while ago - see if there is anything helpful in that link.
 

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Re-reading the 'low pedal' thread suggests two things. 1) wait a day and re-bled the system. B) check to see if the push rod from the pedal to the master cylinder is adjustable. 'B' sounds a bit more difficult as the booster/master would need to be removed I assume.

Here's a link to info about R/R'ing the clutch pedal pivot (a known Alfa weakness). The brake pedal shares the pivot point with the clutch pedal. If you proceed to removing the pedals, consider replacing the clutch pivot arm with an up-graded version.
 

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Not sure, but isn't there an "O" ring on the end of the master cylinder where it mounts against the booster? Not that is the problem. I would rebleed the brakes the old fashioned way = one at a time. Start with the left rear and work clockwise arround the car. Have your assistant pump the pedal hard three times and hold it down, then you open the bleeder, close the bleeder and repeat beyond "no bubbles" at least three times per wheel. Check the resorvoir as you continue and fresh fluid. If you don't have a pedal after this operation, you have a bad m/c.
 

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Discussion Starter #7
Not sure, but isn't there an "O" ring on the end of the master cylinder where it mounts against the booster? Not that is the problem. I would rebleed the brakes the old fashioned way = one at a time. Start with the left rear and work clockwise arround the car. Have your assistant pump the pedal hard three times and hold it down, then you open the bleeder, close the bleeder and repeat beyond "no bubbles" at least three times per wheel. Check the resorvoir as you continue and fresh fluid. If you don't have a pedal after this operation, you have a bad m/c.
Yes, I replaced that O ring with the new master cylinder. I'll bleed them again tomorrow, single caliper at a time. BTW I did just check that valve mentioned earlier and I was blue in the face blowing through it before it finally worked. I'll clean that tomorrow before bleeding again. Thanks for all the suggestions its provided a few more avenues.
 

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I have experienced serious problems trying to get new master cylinders to push fluid through all sections of line and to expel air columns, until I began to bench bleed the master cylinder prior to installation. Then, during the bleeding process, I kept a sharp eye on the fluid level in the reservoir and I left the cap loose also.

Set up the new master cylinder in a bench vise, level. Fab up a very short, curved brake line with fitting for each discharge port. Get some clear vinyl flexible tubing and slide it over the steel brake lines, terminating them into a jar with brake fluid in it. Fill the reservoir, and slowly push the pedal pushrod in and out to fill the chambers and port areas. Refill as needed, and when you get nothing but solid fluid out of all ports, you're ready to go. Have some plastic port plugs ready (most new master cylinders are shipped with them to keep out dirt), remove each brake line and plug the ports.

On install, lay shop rags under the master cylinder to catch the inevitable drips as you remove the plugs and thread in the brake line fittings. BYW, I've found that Speed Bleeders work great to reduce time and aggravation of system bleeding. They allow you to leave the bleed ports open until you're done.
 

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Discussion Starter #9
Thank you all, I now have a phenomenal brake pedal. Bleeding with the cap off the reservoir and cleaning the check valve at the intake did the trick. Now on to the center tie rod ends, tranny mount, diff seal, clutch flex line....:)
 

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Good news! Thanks for replying with the 'cure' - that'll add to the Alfa knowledge base.

BTW, have you considered making a donation to the BB? There is a link at the top of the page. Such donations (plus clicking on the occasional advertisement) will help keep this BB alive. Although it is 'free', I think this BB is priceless.
 
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