After fitting the new master cylinder bleed all wheel cylinders.. Check the booster by pumping the brake pedal several times with the engine stopped, hold pressure on the brake pedal and start the engine, the pedal should move down a small amount if the booster is working ok, if not check there is vacuum at the hose to the booster, On petrol motors the hose runs from the inlet manifold to the booster, diesel motors from the vacuum pump to the booster. If still no stopping power, check all wheel cylinders to make sure they are seized up. If ABS brakes are fitted get a mechanic to bleed them.
1: inspect all brake linings first.
no pulling left or right braking?
the car has 100% full manual brakes. if the brake booster fails.
(its only and assist !!! for 50lb small folks)
so does it? it takes more pedal pressure but has 100% full braking.
this is no accident its by design.
make sure none of the brake shoes/pads are soaked in DoT3/4 fluid
or grease or gear oil.
and no brake fluid leaks end to end, this is really #1 on all cars.
look, then look again. even behind and in front of the master cylinder.
look at tires (inside for fluid leaks>)
2: do the booster test. did the vacuum hose to it fall off?
or got pinched, or ?
google brake booster test
if ABS system. get it all checked,
if ABS get the ABS scanned.
if you cant stop correctly,,,,???? , dont drive.
get it fixed.
why not post the full story? did you touch things?, or did it just fail, all by its self.?
did the engine stall?
if the pedal is only hard to press but with a guy driving and he pushes hard, and car stops normal, only pedal pressure is hard.
then the manual brakes are ok but only the power assist brake booster is bad. (engine running is a must to have booster full time)
answer the questions. its not hard.
or
does hard mean.?
1: stopping distances are too long.
2: or only the pedal feels hard car stops fine.
which is it and does engine stall.
if the pedal is hard to depress, only.
then the pedal it self can be bad.
or even the MC siezed.
any brake man can tell you all this in 5min flat, why not let him/her.
most will do these tests for free. so you are safe , see?
my guess, is if you have to ask, this, you need a real brake man.... (safety matters here)
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double posted with "problem" added...
is the engine running? or not.?
if the engine stalls, the brake pedal gets harder to depress but the car stops ok.
why not till the full story.
when did the work right last. 5 year ago.?
the story matter, please tell it.
if its a engine stalling problem say so.
as that matters first.
if cars stops ok and only the pedal is hard to push get the brake booster checked.
and vacuum is ok to it. (engine needs to run at 800 RPM to have proper vacuum)
is the ABS light glowing , running.
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