Tl Magna brake pedal sinks

[gibbo454]

I just noticed when the car is stopped and engine running, I press on the pedal hardish it will slowly sink down almost to the floor. The brakes are very good in normal use but the pedal is not "hard" on application. I just changed the front discs and machined the rotors but I'm not sure if it was always like this (wifes car i don't drive it much). I can't see any leakage anywhere.
Can someone tell me if theirs does this too?I'm not sure if it's normal or not.

[DeanoTS]

I just noticed when the car is stopped and engine running, I press on the pedal hardish it will slowly sink down almost to the floor. The brakes are very good in normal use but the pedal is not "hard" on application. I just changed the front discs and machined the rotors but I'm not sure if it was always like this (wifes car i don't drive it much). I can't see any leakage anywhere.
Can someone tell me if theirs does this too?I'm not sure if it's normal or not.

I'm no brake expert but sounds like the master cylinder is due for an overhaul or replacing.

[gibbo454]

Is it the master cyl though? Or is it the ABS module or is it normal? That's why I am asking what other peoples Magnas do? Anyone?

[DeanoTS]

Is it the master cyl though? Or is it the ABS module or is it normal? That's why I am asking what other peoples Magnas do? Anyone?

No its not normal at all for the pedal to sink to the floor, the seals in the master cylinder start to let brake fluid past when they get old, don't know if the ABS is causing this sorry

[cooperplace]

Engine on and car stopped, on mine the pedal goes about 2/3 to the floor. Seems a bit soggy. With engine off, the pedal goes less than halfway then feels like a rock. My brakes are fine. They sound a bit like yours, but mine doesn't go to the floor.

[gibbo454]

Engine on and car stopped, on mine the pedal goes about 2/3 to the floor. Seems a bit soggy. With engine off, the pedal goes less than halfway then feels like a rock. My brakes are fine. They sound a bit like yours, but mine doesn't go to the floor.

Yes that sounds the same as mine, 2/3rds to floor. I checked my work car today, a Mitsi Outander with 15k on the clock, it does it too. Maybe it's something that cars with abs do?

[mcs_xi]

Yes that sounds the same as mine, 2/3rds to floor. I checked my work car today, a Mitsi Outander with 15k on the clock, it does it too. Maybe it's something that cars with abs do?

There is a larger vacuum diaphragm bolted to the back of the pedal between the brake master cyl and the firewall. This is 'power brakes'. It uses engine vacuum to work. Naturally with the engine off there is no vacuum.

Mike

[gibbo454]

Yes engine is running while testing