Master Cylinder change destroys Brake Booster?

[Ultranpthing]

Hi all! So, I was losing pressure in my brakes, pretty awfully. The pedal would go all the way down to the floor, and then the car would just start moving again. I took it to Midas, and they told me it was my rear brakes (The pads or rotors or whatever were down to bare metal) and they said I also needed a new Master Cylinder.

Okay. They do their thing.

So I take the car home and notice, on the way, the sound of an air/vaccum leak sound (Which up until the repairs were done, I had not heard before). When I turned the car off, the sound sort of...carried over for a few seconds, then dropped off.

I tested it to see if in fact this had something to do with the brakes. When I pressed down on the pedal, the airleak sound went down a bit.

I brought it back to Midas, and the guy there sprayed brake cleaner on the various tubes and hosing, and when he sprayed the tube near the master cylinder cover, the engine died.

He tells me that it's my vaccum brake booster, and that the part alone costs roughly $500, not to mention the 2.2 hours of labor @ who knows how much.

I asked him if this damage could have been the result of the previous brake work/MC Change, and he said "No.". I also asked him if this issue could have been spotted while the other work was being performed, and he said "No. It's something that shows itself after you replace the Master Cylinder."

So now I'm asking all of you

Could their work on the rear brakes and master cylinder have caused damage to the Vaccum brake booster? This airleak sound, mind you, only appeared after they (Midas) did the work.

Also...$566 for the part alone? AutoZone wants $150 out the door, and I found a used one on eBay in "Excellent Condition" for $14.99.

Any advice or help would be very much appreciated here.

- Josh

[TheSilentChamber]

Yes it could have been damaged by them, and that does sound insanely high. I would go to a real shop and get a quote (by real... I mean try to stay away from the big chain shops like midas).

[MagicRat]

When you press down on the brake with the engine off, do you still get 1-3 power brake applications, or is the pedal hard right away?

I suspect the hiss is your vacuum reserve that should be stored in the booster is leaking away.

It could be the rubber diaphram in the booster is leaking, or a seal. Possily your pressing the pedal to the floor over- worked an already damaged and deteriorated diaphram. In this case, your booster was about to go anyways and had nothing to do with the work that was done.

I am not a fan of Midas, but it is exceedingly difficult to damage a booster, just by changing a master cyl.

Finally, avoid these chain stores. Often they give the mechanic a commission on all parts he sells/installs. Therefore, the parts end up being over priced and the mechanic is encouraged to seel to you all the parts he possibly can, whether they need replacement or not.

[GMMerlin]

It sounds like he cracked the check valve at the booster.
Since you said he sprayed cleaner in that area and the engine died, that is a good indication that the valve is cracked and you have a vacum leak.
Usually when a booster is bad and leaks at the diaphram, you will here a vacum sound inside the vehicle when you apply the brakes.
A check valve is 10-20 bucks from your local auto parts store and doesn't need any tools to install.

I am not a fan of aftermarket chain repair facilities for several reasons.
1. Most of their "technicians" have little or no real experiance repairing vehicles
2. They charge (sometimes double charge) for repairs..had a friend who had a rear brake job at a chain store..advertised price was 39.00 an axle..the total price ended up being over 400 dollars.
Charges included removal and reinstall rear drums (car had rotors), 3 pints of brake fluid, additional charges for having the park brake mechanism as part of the caliper.
3. The mechanics are paid commission on the parts they sell..this can lead to some questionable parts replacement recommendations.

You got screwed and lied too....

[asemstr]

I agree with GMMerlin, sounds like a bad checkvalve or grommet leaking! But I'de also like to point out the fact that a leaking master cylinder bore seal can result in brake fluid in the booster which is a sure booster (and booster warrenty!) killer! And the #1 reason for master cylinder replacement is exsternal, or internal leaks!

[TheSilentChamber]

Do you yell alot?

[asemstr]

Really didn't notice, guess I've been to busy tuneing my obnoxious rambleing out!