motohegg

Constant air bubbles while bleeding the brakes. I used 1 L of fluid just on the RR corner. I knew it was weird, but kept hoping the bubbles would stop at any time. The car is a 2011 and has only 42K miles and hasn't really been molested, so I think all of the brake components are in good shape.

Not sure how much this is a contributor, but while bleeding the brakes a few weeks ago before my track day I used some old brake fluid that had been opened. I know...dumb. Could that cause tons of air bubbles in the system? I've checked that the bleeder screw is only loosened enough to let fluid out and there are no leaks in the bleeder hose on the bottle.

There doesn't appear to be any leaks because the pedal feels like it always does, there are no drips on the floor, and there were no braking issues at my track day a week ago.

I'll bleed the master cylinder tonight and then start again at the RR. The car has been on jack stands for a few days now and my wife is getting tired of the car taking up the whole garage.

Any other ideas?

9krpmrx8

iTrader: (46)

If you used older brake fluid then it could have had moisture in it. If not then you just are not bleeding it right and if you got a bunch of air in the system then you may never get it all out if you are not doing it right.

motohegg

Could be user error, but it's just more air coming out of the bleeder valve than I've seen with any other cars or motorcycles that I've done in the past.

Then again, I've never used old fluid before and maybe I'm experiencing the effects first-hand. Researching online, probably the brake fluid had become saturated with water over time and when I was at the track the fluid boiled.

From howstuffworks.com: "When the brake fluid boils - especially when there is excessive water in the system - steam is a by product. The braking system ultimately compresses this steam and turns it into water. The air separates from the water and before you know it, you have large pockets of air in your brake lines."

Hopefully it's just a shitload of air in the system which proper bleeding will remove.

9krpmrx8

iTrader: (46)

Yeah man, I would just start all over, and use a mitivac style pump or something similar to push all the old stuff out. These cars can be a bitch to bleed, especially the clutch.

dannobre

iTrader: (3)

You must have an air leak somewhere. Did you disconnect any lines anywhere else?

Is the bleed screw out too far? If you open it too much it can suck air in through those threads and seem like its coming down the system

motohegg

I haven't disconnected any lines. Yeah, some air may have been seeping in through the threads under negative pressure. I'll use the two-man (or in this case, my wife) method and be careful about timing when closing the bleed valve. Thanks for the post.

motohegg

Alright, thanks for the input, guys. No more air bubbles! The two-person method worked great.

dannobre

iTrader: (3)

Well you at least know you got rid of the old fluid 😉