Brake Pedal sinking, dirty fluid cause?

[ItsBlack]

Hi.

Ok, yesterday on my way to walmart my brake pedal had no strenght in it at all. I went home and parked. I tried to pump the pedal with the car off with no luck. It doesn't stiffen up aat all unless you don't press on it for about 20 seconds, then it will feel stiff at first and sink shortly after. I used my skateboard as a wedge and tried to bleed the air out of the system, but it had no effect (and I saw/heard no air).

I don't see a single leak anywhere on the system. It appears to be bone dry around all hoses, dust and all. When I open my brake cap, I notice my fluid is grungy dark gold and hard to even see through. Is the dirty fluid causing this?

[81911SC]

You check the MC real good?

[X-Runner]

Check calipers/wheel cylinders. If not MC is going bad.

[ItsBlack]

I didn't see anything at my MC but I'll check again. And I have calipers all the way around and just changed my front two about a month ago when they locked up on me after getting off the highway one day.

This is a devil car!

[X-Runner]

You won't see it leaking, it is leaking down pressure on the inside.

[ItsBlack]

oh..

[ATL86]

Just for shits and giggles, have you bled the system? Fluid level fine? No leakage onto booster?

With the car off, pump the pedal as much as needed to get it firm. Release and press down again. If it drops lower, you have air in the system that needs to be bled.

[ItsBlack]

umm.. did you read?

Hi.

Ok, yesterday on my way to walmart my brake pedal had no strenght in it at all. I went home and parked. I tried to pump the pedal with the car off with no luck. It doesn't stiffen up at all unless you don't press on it for about 20 seconds, then it will feel stiff at first and sink shortly after. I used my skateboard as a wedge and tried to bleed the air out of the system, but it had no effect (and I saw/heard no air).

[ATL86]

Umm... yes I did. That isn't bleeding properly. When you loosen the bleeder screw and release pressure, the weight of the skateboard needs to be enough to push the pedal all the way to the floor, forcing the fluid through. You need someone to sit in the car and push the pedal for you, or buy a one-man bleeder.

Also, dirty fluid will not cause a sinking pedal unless it has started to break down seals in the calipers, which is not common, especially in your case. The fluid doesn't seem too dirty to me by your description.

If there are no leaks in the lines, connections, bleeder screws, and master cylinder, the fluid level is fine, AND you've properly bled the system (RR-LR-RF-LF) then I'd point towards the master cylinder.

[hondaxpurt]

Umm... yes I did. That isn't bleeding properly. When you loosen the bleeder screw and release pressure, the weight of the skateboard needs to be enough to push the pedal all the way to the floor, forcing the fluid through. You need someone to sit in the car and push the pedal for you, or buy a one-man bleeder.

Also, dirty fluid will not cause a sinking pedal unless it has started to break down seals in the calipers, which is not common, especially in your case. The fluid doesn't seem too dirty to me by your description.

If there are no leaks in the lines, connections, bleeder screws, and master cylinder, the fluid level is fine, AND you've properly bled the system (RR-LR-RF-LF) then I'd point towards the master cylinder.

X2. Good answer

[ItsBlack]

Umm... yes I did. That isn't bleeding properly. When you loosen the bleeder screw and release pressure, the weight of the skateboard needs to be enough to push the pedal all the way to the floor, forcing the fluid through. You need someone to sit in the car and push the pedal for you, or buy a one-man bleeder.

Also, dirty fluid will not cause a sinking pedal unless it has started to break down seals in the calipers, which is not common, especially in your case. The fluid doesn't seem too dirty to me by your description.

If there are no leaks in the lines, connections, bleeder screws, and master cylinder, the fluid level is fine, AND you've properly bled the system (RR-LR-RF-LF) then I'd point towards the master cylinder.

ok, gotcha. Apologies, i'll work on that tomorrow.

but, i do feel the skateboard was pushing the pedal hard enough. It was wedged between the seat and the pedal and fluid would drip out whenever I loosened the screw, but hey you know more than I do.

[ATL86]

It may be wedged enough to hold it down, and when pressure is released, it will probably force the pedal down a little but more than likely lose its "wedge" and just kind of lay there on the pedal, lol. Grab a bud to help you properly bleed the system.

[Barefoot]

rebleed the system
check for external leaks at cals, mc, and pp
if all is well ill put my money on your mc is shot.

[Tensa_Zanget]

rebleed the system
check for external leaks at cals, mc, and pp
if all is well ill put my money on your mc is shot.

yup! GL