premature brake master cylinder failure

[AaronA]

My 2001 V70 has 124K miles on it. In May of 2011, at 109k miles, I replaced the brake master cylinder and shortly afterwards, the brake booster. The brake pedal has started to sink to the floor again when stopped, and the reservoir is still full. Looks like my master cylinder is fried again. Any ideas on why it would fail so quickly?

Was it because:
1. It's a sucky part?
2. The DOT 4 brake fluid I got at autozone caused the seals to fail?
3. It's a sucky part?

I bought it at FCP so I'll call them later today to see if they'll help me out at all, but I don't have high hopes. I really don't want to be replacing the master cylinder more often than my brake pads - any ideas? I also think I'm going to have to get a new one from the junk yard as I can't afford another $300 for a part I just replaced. Any thoughts on that?

Thanks,
Aaron

[AaronA]

Just a quick update - FCPgroton is not standing by their parts. I was told "it is more than a year, there is nothing I can do for you."

[mbreed]

If it is a rebuilt part i would say it failed. I doubt the brake fluid is to blame.

[draser]

^2 on brake fluid, I've been using that on several cars for years. It's like you said... sucky part.

[JimBee]

I have seen a lot very clean looking master cylinders on 850's in the junk yard. I don't know if that means anything, but I if I had to replace mine I'd probably pick up clean looking one and rebuild it with a kit from a brake specialty supplier.
Or you might try this:
http://www.rockauto.com/catalog/x,carco ... ttype,1836

[AaronA]

If it is a rebuilt part i would say it failed. I doubt the brake fluid is to blame.

It was new part, or at least it was sold as one. I think the Ate part just sucked. I ordered one from Erie Parts. $50 and I was told if it ever failed, they would send me another.

I was doubtful that it was the brake fluid, but couldn't think of any other reason for the part failure.