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Help! The dreaded 3 port brake master cylinder 4601 K9
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Author:  BOOTHEGERMANSHEPHERD [ Wed Nov 26, 2025 6:41 pm ]
Post subject:  Help! The dreaded 3 port brake master cylinder 4601 K9

Hi

As it says, I'm hoping someone can help with sourcing this obsolete part?

4601 K9

The spare port is for the ESP pump to pressurise the system

I am wondering if its possible to install a two or 4 port and connect the ESP pump in with a T piece to the two port or blank off the spare port on a 4 port?


The issue is that the system is holding pressure after the brake pedal is released, this is help by the primary circuit of the master cylinder not returning the fluid .

The cylinder is the same style and internal operation as this you tube video which was very helpfu



lhttps://www.youtube.com/watch?v=u9FZbpNmyqk



The thing is that fluid return on the primary circuit has to go back past the centre of the piston rod when the pedal goes back to rest

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