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Discussion Starter · #1 ·
Bled brakes......after replacing leaking master cylinder
No visable leaks.

Engine off and brake pedal pressure is fine

Start the engine and pedal is nearly at the floor to slow car down
Brakes work but not enough to lock the wheels

Any ideas?

Toyota Celica servo and matching 13/16” master cylinder were used in the project - with ABS system removed
Project car has front and rear discs.
 

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richard rawlplug
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Vacuum leak at servo...?
 

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First, clamp ALL the flexys and see what happens then, then release the clamps one at a time and see which brake (if any) makes any difference.....easy stuff first IMO
 

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Discussion Starter · #6 ·
Got another Celica servo from a breaker....but Is there a way to test the vacuum servo?

Pal was convinced my car had a sticking caliper pin as he had experienced the same symptons on another Toyota.
Sadly........but good news for me was all the sliding caliper pins were fine.

So the problem remains untill I can find what is causing it.
 

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Discussion Starter · #7 ·
First, clamp ALL the flexys and see what happens then, then release the clamps one at a time and see which brake (if any) makes any difference.....easy stuff first IMO
Going to blank off the front brake port.....and test with just the rear brakes
and then do the same with back brake port and try again

Should be something simple but as yet I can't see it.
Fingers crossed,
 

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Discussion Starter · #9 ·
Did you use a new Master cylinder?
Both from the breakers

1st one had a small drip from the rear.......noticed a weep down the servo
so replaced it with another..........this time no leak but same pedal to the floor when engine running.

Might get a master cylinder repair kit for the 1st weeping cylinder........if toyota or another sells such a part?

Still to try out the blanking off test and see what happens......mybe have another go tomorrow.
Just can't seem to work out why solid brake but then goes to floor when engine running.
Got me well puzzled on this one.
 

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As has been posted above the starting point would be to clamp all flexibles . Pedal should then be totally solid .If it isn't then you still have air in the system.
 

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Discussion Starter · #12 ·
Are you using the Toyota brakes that came with the m/cylinder ?
It is a Lexus V8 that had an ABS system that I removed and fitted a Toyota Celica normal servo and master cylinder

I used the Celica parts because the mounting studs were the same position in the bulkhead so no modifications needed there.....I thought an easy swop over.

Kev.........I mentioned i had rock solid brakes when the engine was not running
Surely air in the system would still be felt at that stage.
Engine on and the pedal goes to the floor.

Will try blanking off each master cylinder port tomorrow and try again to see if it sinks to the floor when only the back brakes are hooked up,,,,,,,,,if these are OK , I try the same again using only the front brakes,
Again......I'll see what happens when the engine is off and then being started,

I'll also try it with both ports blanked off......this should eliminate the pipes and caliper side and see if it is then servo or master cylinder is the issue.

Servo issue - i'd expect to hear a hiss somewhere
Master may have an internal seal issue........but on both units is bad luck.

Maybe time to hang up ma boots......
 

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