HI, I am experiencing brake pedal sink when I apply the brakes and keep the pressure on. The master cylinder is full, I do not see any leaks and I haven’t done any brake work in months. The car has 182,000 miles on it and it runs great. Any thoughts?

THANKS.

 

Probably the brake booster which is leaking (or the connection to the brake booster)

 

What he said above. You should see a decrease in your brake reservoir. You may not see a leak if it is leaking into the brake booster, through a possibly compromised seal. Have you also check all the caliper to be sure there are no leaks down in that area. Had a slow leak on my Driver's side rear from a loosened bleed valve.

 

Check carefully, we had a soft pedal with a slow drop in fluid level - rusted hard line to left rear wheel. Replaced with cuprinol line.

 

total guess, bad or going bad master cylinder. if the fluids are not going down...

 

noodles and Sam for your input. I had a line weep before and thought the same thing but I haven’t seen an other leak.

THANKS

 

Ssoliman, Thanks for your input. I think I’m going to have to remove the master cylinder and check the seals.

THANKS

 

soooo what was your fix , I have the same issue after new booster , new master , 20x times bleeding it with pressure bleeder and scwaben tool and STILL NO CHANGE !!!

 

You can try a scanner that will actuate the ABS during bleeding. That helped mine some, but did not fix my perpetual excessive pedal travel. I ended up installing a BMW E46 master cylinder and Willwood big brake kit on the front. The brakes are great, but too bad I still have not figured out why I am in limp mode... :(