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Discussion Starter · #1 ·
My 90 graduate has recently began to lose break pressure. If I pump the brakes the pressure comes back. It is full of fluid with no leaks. The master was replaced about 6 years ago.

I am looking for suggestions

Jim
 

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Time to do the master again I think. Sounds like one of the seals has blown. But first I'd bleed all four corners, you may just have air in the lines.
 

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I agree with AlfaTango1 - a bad master cylinder is the most likely cause for those symptoms.

You can try bleeding the brakes, but I really doubt that will fix it. Two reasons: Air in the lines doesn't go away when you pump the pedal. Even if there is air in the lines, and you expel it by bleeding, there is still a problem; air doesn't just appear in the lines when everything is OK.

Six years does seem like a short lifespan for a master cylinder. An Alfa master sits right above the exhaust header; is it possible your car has unusually high underhood temperatures? Perhaps you have a tubular header?
 

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Discussion Starter · #4 ·
Jay...

The car runs around 175 however there is no 'heat shield' over the stock headers. Could that be a problem?

Jim
 

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The car runs around 175 however there is no 'heat shield' over the stock headers. Could that be a problem?
I'm not sure. Did 1990 spiders come with a heat shield around the MC? As long as your car has its original exhaust manifold, and no heat shield has been removed, I doubt that's the issue. All my experience is with earlier spiders and they work OK with no shield.

Another possibility: newer brake fluids are not compatible with some types of hydraulic seals. I'm no expert on this, but just read a recent BB post on this topic. See post #9 in the thread at: http://www.alfabb.com/bb/forums/spider-1966-up/426138-gripe-gripe-gripe.html#post6326642
 

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Discussion Starter · #6 ·
Jay ...

As a backup I ordered a new MC from Vicks. I will install it ... bleed all four brakes and see where we end up.

Thanks for the advice!

Jim
 

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2015 Chevy (Holden) SS, 1989 Milano (Shankle Sport), 1991 164S
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Be sure to use the very high temperature rated ATE 200 brake fluid. This ultra high temp rated fluid cured the fluid boiling problem my 91 164S had several times, the very tight engine compartment temperatures being probably the highest of all Alfas, esp in hot stop and go driving.
 

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As a backup I ordered a new MC from Vicks. I will install it ... bleed all four brakes and see where we end up.
That should solve your problem.

While you have the MC off the booster, check if there is any brake fluid down in the booster. You can do this by sticking a rolled up paper towel down into the booster, withdrawing it, and seeing whether the tip is wet. If there is fluid in the booster, get it out as best you can - if there is a lot, use a turkey baster. Otherwise, use paper towels.

Note that fluid in the booster would NOT cause the symptoms you experienced. But over time, brake fluid will destroy the booster. Most likely, your booster is dry. But the easiest time to check for and cure this problem is when you already have the MC off.
 

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Discussion Starter · #9 ·
To lose out the thread ... the MC was bad, the Booster was fine... and I ended up rebuilding all 4 calipers, new rotors all around, and new wheel bearing seals. A complete system rebuild. It has been 9 months and all is fine.
 
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