1990 Volkswagen Golf Bleeding of Braking System

ADRIANB

MEMBER
1990 VOLKSWAGEN GOLF
4 CYL
FWD
MANUAL
156,000 MILES

I have bled the brakes 3 times. No air bubbles etc. Were found. They are still spongy and every now and then has a serious flat spot where the brakes do not stop the vehicle at all and the pedal goes to the floor. After pumping once or twice (most times only once) the brakes then work as normal. The flat spot seems to happen only at low speeds (in traffic) This may be coincidental, but is not consistent.

I have checked for leaks and found none. I have also kept an eye on the fluid reservoir and no abnormal usage was noted.

Am I missing something?

1 Reply

MHPAUTOS

MECHANIC
31,938 POSTS

Hi there,

You may have a faulty master cylinder that is by-passing, that is fluid is leaking past the piston seal under pressure, this will not show up as an external leak, normally you can test this by holding the brakes on with light foot pressure and the pedal will slowly sink, pump the brakes up and use heavy pressure and the pedal will normally stay up as there is more pressure on the seal surface you don't get the leakage with light pressure.

Mark (mhpautos)