1985 Other Mini Models BLEEDING BRAKES

Tiny
MINIMAN
  • 1985 MINI

Brakes problem
1985 Other Mini Models 4 cyl Front Wheel Drive Automatic 38000 miles

I FOUND A LEAKING WHEEL CYLINDER ON NEARSIDE REAR, AND DECIDED TO REPLACE THE THE RUBBER SEALS ON THE PLUNGER INSIDE THE CYLINDER, THE CAR WAS ON LEVEL GROUND AND JACKED UP AT THE BACK POINTING THE FRONT DOWN. NORMALLY WHEN IVE ONLY DONE WORK OF THIS KIND ON ONE WHEEL IVE FOUND IVE ONLY NEEDED TO BLEED THAT WHEEL. THERE WAS SUFFICIENT FLUID IN THE RESERVOIR, AFTER BLEEDINGTHE AIR OUT BY MEANS OF JUST GRAVITY INTO A JAR THOUGHT THAT WOULD DO THE TRICK, BUT FOUND NO BRAKE AT THE PEDDLE. THOUGHT ODD. STILL PLENTY OF FLUID IN RESERVOIR. PROCEDED TO BLEED EVERY WHEEL UNTIL CLEAN FLUID RAN CLEAN FROM EACH WHEEL. EVEN BLED OPPOSITES FRONT/BACK IN SEQUENCE AND BOTHBACKS THAN BOTH FRONTS IN PAIRS. STILL NO BRAKE AT PEDDLE. IM STUMPED. BEFORE I DECIDED TO CHANGE THE LEAKY CYLINDER MY BRAKES WHERE FINE, NO SPONGY NO PROBLEM, JUST A MAINTENANCE JOB I THOUGHT. WHAT AM DOING WRONG. BILL

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Saturday, June 5th, 2010 AT 6:35 PM

5 Replies

Tiny
MHPAUTOS
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Hi there,

is the master a newer type alloy or older type cast iron master cyl?

Mark.

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Saturday, June 5th, 2010 AT 8:10 PM
Tiny
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Hi Mark, had a uneasy nights sleep dreaming about what may be the problem, lol. Lol.

The master cylinder that you pore the fluid in is plastic. My car is a mini mayfair 1985 auto.

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Sunday, June 6th, 2010 AT 2:27 AM
Tiny
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The actual body of the master cyl will be either cast (dark looking) or alloy (light looking) the plastic reservoir is attached to this.

Mark

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Sunday, June 6th, 2010 AT 2:43 AM
Tiny
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Hi Again Mark, oh right, its definitely not ally. I would say cast iron. Bill

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Sunday, June 6th, 2010 AT 2:59 AM
Tiny
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OK, What I feel has happened here is that with cast iron cylinders they tend to get a lot of muck and deposits on the bottom section of the cylinder, now this is not a problem during normal operations, but if fluid is not changed on a regular basis, this muck builds up, still not a huge problem un till we bleed the brakes, with bleeding the master cylinder piston travels down onto this muck and the primary cup can get damaged, if so you start to get fluid by-passing under load, if you have no air, and good fluid flow, I think that the master is damaged and need replacing.

Mark (mhpautos)

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Sunday, June 6th, 2010 AT 6:24 AM

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