Do I have a bad master cylinder? - Toyota Nation Forum : Toyota Car and Truck Forums

RU2CHKN · 01-09-2011, 06:08 PM

Hello all, my gen v6 has 163,000 miles and I was wondering if I have a bad master cylinder. I'm noticing a spongy brake pedal and I had already bled the brakes a few times before. I replaced my brake lines as well as the hoses and havent noticed any leaks. The resevoir is still full with brake fluid and the brake light intermittently goes on and then stays off. I've also had new calipers so the pins aren't sticking. My brake pedal doesnt sink to the floor like one of the main symptoms of a bad mc. Can anyone tell me if my master cylinder is going bad because I don't want to drive one day and have the brake pedal sink to the floor

***JohnGD*** · 01-09-2011, 07:50 PM

Do you begin to feel braking with little pedal travel? Or do you feel it slowing only after 1/3-1/2 down?

With the engine off and vacuum used up, see if the pedal drifts toward the floor with light pedal pressure. That's another sign of MC cup leaks.

It may also be air in the ABS system. Otherwise have it checked by a professional.

RU2CHKN · 01-09-2011, 11:14 PM

Forgot to mention it's non-abs and I do start feeling pedal feel about 1/3 of the way down. The car still stops likse it should but it just feels spongy.

AmericanAirFan · 01-10-2011, 12:04 AM

Man, I had a very expensive ordeal last week with my Camry.... Replaced the rotor and brake pads on the front.... It felt spongy even after bleeding the brakes (no pressure until 2/3rd of the way down at least. Decided to have our mechanic look at it. He said it was the master cylinder.... Spent a fair chunk of change on that to figure out that wasn't the problem. Ended up some clips were not on the brake pads that needed to be.... So ends up the brake pads all 4 of them got bent.... First time our mechanic or any of the mechanics he has working with him has ever seen that before.... It cost us a pretty penny.... Strange thing was the pads had all the same clips that we saw on the old pads we took out but the new pads our mechanic showed us had additional clips/spacers.... I hope you get it figured out!

RU2CHKN · 01-10-2011, 12:19 AM

Thanks and wow, I just looked at my clips and they all looked good. The brakes still feelt firm after bleeding the whole system but about a couple weeks later it gets spongy.

RU2CHKN · 01-22-2011, 02:03 PM

Here I am bench bleeding new master cylinder: http://static.photobucket.com/player...9-16-22-07.mp4