My brake pedal felt spongy about 3 weeks ago. I had the brakes flushed in november. The dealer says a seal maybe leaking in the MS but I dont think there arent any leaks that I can see? I have no pressure loss when you pump a couple times and hold when you have the car off. I have noticed the pedal drop a little bit(not to the floor) if I am in idle while I hold the pedal its drop slightly more when the AC is running if.

Does this sound like the cylinder they want $500 to replace. If this is the case would going to firestone or something like be an ok alternative?

2006 MT

Thanks,
Luger

 

I'd bleed the brakes again, and see what happens. Typically, a master cylinder will show up as a slowly sinking pedal with very light pedal pressure; like sitting at a stoplight. Colder weather sometimes aggravates the problem. If you do decide to replace it, try an independent import specialist. It ain't rocket surgery, and it will be cheaper. Make sure you get a new as opposed to reman cylinder.

 

Luger, I had the same experience with my TL. When the car was off, the pedal was nice and firm, but once I started it, it would get soft and I could depress the pedal quite a ways. Did a thorough bleed/flush procedure as described in the factory service manual and it did the trick. Give it a try.

 

Pedal should hold fairly solid when at idle and after warm up. Normal operating temp, in neutral, press and hold the pedal with parking brake released for @ 3 minutes. Less than 3/8" drop, MC is OK, more than 3/8" drop problem. This is with the assumption that the balance of the hydraulic system has no leaks/air.

When one feels the pedal sink when stopped and in drive at the time the A/C cycles on and off that is normal as the A/C compressor load changes the vacuum available to the booster.

 

Thanks guys. I had them bled and so far it seems to be better. So I may have saved some money which would have been a waste for a master cylinder I didn't need.