Just finished servicing the brakes on my car but am having problems getting a firm pedal when engine running.
When I press the pedal with it off I get a really firm pedal but with the engine running it sinks to the floor. The brakes seem pretty weak although they do stop the car. Not able to take it out on the open road as it's not motd.
All calipers are free to move and I've bled the system completely at least 6 times! No visible leaks st all and the master cylinder area is bone dry.
The brakes were pretty spongy before I serviced them but not as bad. After replacing seized caliper pins I thought the job would be a good one.
Handbrake is working great not that's much consolation.
Any ideas guys ??


2000MY 3.0 V6

 

No car details??
No year?

It helps to have that.
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there seems to be a lot of cars with same fault s type I assume?

 

Hardly any have had it. Unless you meant the owners failing to put in car details in which case yes all too often

 

Hi Dave

It sounds like the master cylinder has failed.

This can occur when you work on the brakes, and when bleeding, pump the pedal to the floor. If you have done this. What happens is the brake pedal goes past its normal travel, and the seals let go due to grooves/score marks from normal use.

If you put a bit of wood under the pedal that lets you stop within normal brake pedal travel and then bleed the system it can prevent this happening.

I hope this helps
Paul