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Old 22nd December 2020, 03:37   #1
Mogmike
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Default Brake pedal long travel.

I have recently replaced the head gasket and all running fine but my brake pedal now travels a long way before I feel any breaking. I haven't touched the brakes and the only thing I've done is remove the vaccum pipe from the inlet manifold. On my test runs the brakes seem very wooden and it's as if the servo is not working. Doesn't feel safe to drive in traffic. One niggling thought is that I had a similar issue with brakes a while ago but I literally yanked the pedal to one side and the brakes came right and worked probably again. Trouble is I can't remember exactly what did but wonder if any one has had a similar issue with their brakes and found what it might be.? Or any comments on the servo and any known issues..
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Old 22nd December 2020, 08:10   #2
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It might be worth checking the brake fluid level, it sounds unconnected to the engine work and the brake servo.


My experience of brake servo failure is the pedal becomes firmer and the travel much shorter, not as you describe.
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Old 22nd December 2020, 11:48   #3
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Bit of a puzzler.


Pedal travels a long way.
Brakes feel wooden as if servo not helping.


I would have thought lack of servo assist would shorten pedal travel as well as the wooden feeling.




Only braking item disturbed during work is vacuum pipe. Suggest you make sure it's back correctly and securely and isn't perished at all. Any doubt, replace it.
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Old 22nd December 2020, 12:20   #4
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On my project zt one minute the brakes were fine , the next nothing, pedal to the floor.
As it had been stood for so long I suspected one of the seals to a caliper had failed which in fact it hadn't.

Apparently the seals on the master cylinder can flip, brake servo failure is quite rare and easy enough to check with the engine running.

Also check the pipe hasn't come off to the servo or broken especially where it bends.
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Old 22nd December 2020, 12:57   #5
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Check the seal on the vacuum pipe from the servo to the manifold where it enters the manifold. No vacuum will mean no servo assistance.
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Old 22nd December 2020, 13:10   #6
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An inoperative brake servo would give a stiff pedal with shorter than normal travel, I suggest looking more at the hydraulic side of the system.
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Old 22nd December 2020, 14:03   #7
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Quote:
Originally Posted by bsafly View Post
An inoperative brake servo would give a stiff pedal with shorter than normal travel, I suggest looking more at the hydraulic side of the system.

This was my thought, but without any disturbance to the braking system, it can only be co-incidental to the head gasket work.
A popped caliper seal, leaking union, split hose, or master cylinder/servo issue are all possibles.
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Old 22nd December 2020, 17:59   #8
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Quote:
Originally Posted by Ched View Post
On my project zt one minute the brakes were fine , the next nothing, pedal to the floor.
As it had been stood for so long I suspected one of the seals to a caliper had failed which in fact it hadn't.

Apparently the seals on the master cylinder can flip, brake servo failure is quite rare and easy enough to check with the engine running.

Also check the pipe hasn't come off to the servo or broken especially where it bends.
Old wives tale those flipping seals.----


If they could do that then in emergency braking when you are applying a large amount of pressure to the brake pedal the seals would flip.

That old tale will just not go away.----
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Old 22nd December 2020, 18:03   #9
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As others have said, make sure you have a vacuum at the servo.
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Old 22nd December 2020, 19:28   #10
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Quote:
Originally Posted by COLVERT View Post
Old wives tale those flipping seals.----


If they could do that then in emergency braking when you are applying a large amount of pressure to the brake pedal the seals would flip.

That old tale will just not go away.----
Tbh I didn't believe it myself Jon, someone mentioned it to me at the time but, as its engineered by a human anything is possible.
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