When I bled the system I had a friend doing the braking and when i was bleeding the left front I heard a hissing sound from where the main brake cylinder is. When I put my hand down on the right side of the mailn I felt an "airpuff" every time he braked...

Is this normal or do I have to change anything??

:confused:

 

That's not normal...

 

Would like to help, but need more info!

Such as are you talking about air at the caliper? Did you get any fluid at all?
Why were you bleeding the system anyway? What had/have you done that requires bleeding?

Jack

 

Not sure about the "air puff" [not going there]. But I would suspect you might have a problem with the vacuum booster? Hiss sound [not going there either] with pedal depression is often a booster problem.

Does the car take a good deal of pedal pressure to stop?

 

Thanx!

Yes, it was even hard to keep the car standing still on idle in drive. I changed the brakepads (Pretty worn out) and bled the system, that is when I notised the hiss and "airpuff" (Hey, Im from Sweden ok :p: )

I have not tested the brakes because the car wont start now, have no juice in the bättery left and it wont take recharging...Damn Tudor! getting a new one on monday.
I just thaugt I´d ask if any of you have had the same problem with that puff of air, hiss sound, that comes everytime I brake. I have never braked a fully functional vette so I have nothing to compare with... How will I know that the brakebooster is broke? Would I get a errcode for that?

Toggy

 

Yes, I got fluid at all corners but the brakes dont hold pressure when I press the pedals, The air I was talking about is coming from somwhere around the main cylinder or the brakebooster. I dont know how the brakebooster works, maby it could be it?

By the way, how do I bleed the Mailncylinder?

Thanks
T

 

First, did air get into the MC? This should only happen if you let the resivoir run dry or disconnected the brake lines.

I never noticed air comming out of a booster. It works off of vacume. Not sure why there would be air comming out of it.

If the booster is bad I would think that you would need to apply a lot of preasure on the brake pedal to stop. But the pedal would be firm.

If their is air in the system or the MC is bad, then I believe you should have a spongy pedal that may require a few pumps to firm up. In other words the pedal goes to the floor at first. If the MC is bad, it might not firm up after repeated pumps.

If you have the spongy pedal that firms up, I suggest you bleed the breaks again. Start at the left passenger wheel as it is the furthest. Then rear driver, then front pass, front driver. Be sure to not allow any air back in while bleeding the calipers. There is an inexpensive tool (hand pump) called a mighty vac that can make this a one person job and assure no air gets back in.

If you think air could have got into the MC or you end up replacing it, here is how to bleed it. Get 2 short peices of brake line that will fit the MC. Attach to the MC where the regular brake lines connect. Bend the other end of lines so that they submerge into their respective resiviors. Gently pump the pedal until bubbles can no longer be seen. Then reconnect the original lines and bleed the rest of the system (as you just got air in the lines from disconnecting them)

Hope this helps. I'm sure there are other schools of thought on this as well.

 

I have the exact thing happening. I had a very hard pedal. I decided to add a PB booster to make it more drivable a few years back. I bought booster from MidAmerica or Ecklers (do not remember for sure) and installed it. Now I have a pedal that goes to the floor almost. I have bled the brakes with those new SS check valve bleeders and gotten blue fluid to all wheels. I started at RR and ended at LF. I always change color when bleeding so I will know when all the old fluid has been purged. The pedal is the same with engine running or not. It is getting vacuum. All I can imagine at this point is the booster is bad or these check valve bleeders really do not work and let air back in. Does anyone have experience with these bleeders? Does it almost have to be the booster? Please post if you fix yours!

 

Several things:

1) yes, the speed bleeders do work and work very well

2) if the pedal is the same, with or without the engine running and you do have vacuum, it raises several questions. Not the least of wich is are you driving the car and how does it stop?

3) A worn master Cylinder (piston) can allow fluid to go around it as it travels through the bore, but as you let up on the pedal, it ought to be slow to return to the top since the fluid must go back around the piston to the reservoir side

Jack

 

Toggy,
The hissing sound when you apply the brakes is a sure sign of a bad booster, you'll needed to rebuild it or replace it. There's no error code set.

Eric