Earlier this week my right front brake line failed due to abrasion on the brake caliper.

Now that I've replaced both front lines, the system is still acting like there is alot of air inside. I've bled it so much the fluid is very clean coming out at every wheel.

I've been told that when you have a failure, and you push the brake pedal to the floor, you damage the master cylinder? any truth to this??

Thanks in advance.

Do the car have 4 wheel disc brake or 2 disc + 2 drum type?

David

It's 4 wheel disc, 300e, the Merc shop put a new(to me) ABS part on it, saying that the rear brakes weren't engaging fully, System works now, but feels lots different

Yes, you are correct in assuming that the master cylinder may have been damaged through bleeding the brakes by pumping the pedal to the floor.

Russla,

What ABS part did the shop change? Do you know the part number?


David

[This message has been edited by be459 (edited 08-29-2000).]

Sorry, I don't know the part number,
It's the metal gizmo under the black bosch ABS shroud, where all the metal brake lines go into, it sits in front of the master cylinder. I'm guessing, as I'm not looking at it, but it's about 6in long, 4 wide and 2 thick?

Let me know if you really need the number.

Best Regards

Russ

Russla, MBZ have a dual system. If you lose primary system pressure, there is a backup system further down the master cylinder (so to speak). This requires a great deal of pedal effort and does put the m/c piston near the end of it's travel. If there is air in the system, either at the m/c or in the ABS servos, this will give you the "funny pedal". Not knowing what actually happened in your case, but as you said a line ruptured, there is a good chance you may still have air in the m/c when you lost (I assume) all or nearly all of your fluid. If it hasn't been done the m/c may need to be bled also. I am confused as to why they replaced the ABS assembly, when your casualty sounds like a rapid loss of hydraulic pressure due to a ruptured brake line..did they tell you why the ABS module needed to be replaced. This device has servo valves which can rapidly toggle braking pressure when a wheel loses traction. Don't know why it was replaced. Maybe Steve or Donnie have better info. If I were you, I would find out about that as that component is rather pricey..

------------------
Jeff Lawrence
1987 300e
1989 300e
2000 Dodge Grand Caravan SE

They replaced the ABS part because...
after the new lines were in place and they were attempting to bleed the system, they had continual problems getting all the air out.

Then they noticed a clicking (a relay?) behind the centre console. Which led them to further investigate the ABS unit.

I didn't get a new one, but a used one. The (relay) doesn't click any longer,

The system is working, but the feel is quite different. before the leaks, engagement was soon after I applied pressure, now I have to pust the brake pedal further for the same level of bite.

Best Regards

Russ

[This message has been edited by russla (edited 09-10-2000).]

I JUST GOT BACK FROM THE MIDAS SHOP THAT BROKE MY MASTER CYLANDER ON MY 300E.(WHICH THEY ARE PAYING TO HAVE REPLACED) THEY SAID THE FRONT BRAKES WORKED FINE BUT THE REARS DID NOT AND THE PEDAL FELT A LITTLE SPONGY.
SO THEY TOOK APART THE MASTER CYL. ANREALIZED THEY BROKE IT. HOPEFULLY THIS INFO HELPS YOU OUT ON YOUR CAR.