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Old 6th April 2021, 10:05   #1
pletevl
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Default MG F brake pedal problem

Hi everyone,

Not 75 related, but MGF.

My local ex MG Rover garage here in France has just contacted me, they know I hang around these technical forums.

They have an MGF, LHD, with the brake pedal that goes to the floor. They've replaced the master cylinder, bled the circuit, check everything, and the car still has no brakes and the pedal that goes to the floor. There's no leaks etc.

Any ideas ? apart from a dud new master cylinder ?

Thanks

Pete.
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Old 6th April 2021, 11:21   #2
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Quote:
Originally Posted by pletevl View Post
Hi everyone,

Not 75 related, but MGF.

My local ex MG Rover garage here in France has just contacted me, they know I hang around these technical forums.

They have an MGF, LHD, with the brake pedal that goes to the floor. They've replaced the master cylinder, bled the circuit, check everything, and the car still has no brakes and the pedal that goes to the floor. There's no leaks etc.

Any ideas ? apart from a dud new master cylinder ?

Thanks

Pete.
Not sure how they bled the system, But the last time I had this problem (MGF, with ABS) I had to use a pressure Bleed to purge the system.

Alternatively if they open the bleed screw, leave it open whilst pumping the pedal it sometimes does not push the fluid through it just pushes it backwards and forwards, So then you need to push the pedal down, Lock the bleed screw, lift the pedal This makes sure that the fluid is sucked into the system from the reservoir, Open the bleed screw and repeat.
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Last edited by Number 6; 6th April 2021 at 11:24..
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Old 6th April 2021, 20:45   #3
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Is the MGF with or without ABS?

The first thing I would do is clamp the brake hoses one by one & see if it makes any difference.

I've never had a problem bleeding these but I do use a pressure bleed system now (as said by Number 6).
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Old 7th April 2021, 06:22   #4
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This car has ABS. I know on some cars you have to get the abs pump spinning to be able to get the air out, like on the 75 by using T4. I don't know if the F needs this doing or not.
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Old 7th April 2021, 09:49   #5
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As said above, pressure or vacuum bleeding may be the way forward.


An old method for difficult systems was to clamp the two front flexies and one rear, open the un-clamped bleed nipple and let gravity do its job, when fluid is seen to come from that wheel, bleed as normal, by two people using the pedal up, down, up, down, two or three rapid pushes then close the nipple with the pedal down, till there is no more air, clamp that one and repeat on the other rear, i.e. open the nipple then wait till fluid starts to dribble, bleed, clamp and do the same on the fronts.


With all clamps off, go around them all again and bleed as normal, to ensure there is no more air and you have a firm pedal.
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Old 7th April 2021, 19:28   #6
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An old method for difficult systems was to clamp the two front flexies and one rear, open the un-clamped bleed nipple and let gravity do its job, when fluid is seen to come from that wheel, bleed as normal, by two people using the pedal up, down, up, down, two or three rapid pushes then close the nipple with the pedal down, till there is no more air, clamp that one and repeat on the other rear, i.e. open the nipple then wait till fluid starts to dribble, bleed, clamp and do the same on the fronts.


With all clamps off, go around them all again and bleed as normal, to ensure there is no more air and you have a firm pedal.


Oh how that brings back memories of trying to bleed the air out of old single circuit drum brake (all around) systems!
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Old 7th April 2021, 19:47   #7
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Oh how that brings back memories of trying to bleed the air out of old single circuit drum brake (all around) systems!

Hope you didn't forget to wind all the shoes up to contact the drums first then remember to re-set the clearances after.


These young uns don't know they're born.


Joking aside, these days, many old tricks than can help with modern problems are forgotten.
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Old 7th April 2021, 20:40   #8
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Well, if they're sure they've bled the circuits of air then all that's left is a dud master cylinder.---


As they are ex Rover I guess they know where the reservoir is.---
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Old 7th April 2021, 20:49   #9
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Well, if they're sure they've bled the circuits of air then all that's left is a dud master cylinder.---


As they are ex Rover I guess they know where the reservoir is.---
Its an MGF, Not an MGZT
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Old 7th April 2021, 20:54   #10
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Its an MGF, Not an MGZT
The OP has too many cars.---
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