jim beam wrote:
> Rich wrote:
>
>> Steve Bigelow wrote:
>>
>>> "Rich" <rgsrx@cox.net> wrote in message
>>> news:EA_ue.324$HV1.47@fed1read07...
>>>
>>>> Four days ago I had my 1993 Accord serviced. Among other things, I
>>>> had the brake fluid changed & the brakes inspected. The car has
>>>> 149,000 miles on it, the front pads were replaced at 49,000 miles &
>>>> the rear shoes are original. Anyway, I picked the car up on Monday &
>>>> drove about 12 miles home & everything was fine. Friday I get back
>>>> in the car for the first time & the brake pedal sinks to the floor.
>>>> I check the brake fluid & it is full. I limp back to the
>>>> mechanic(who I trust) who tells me the master cylinder just happened
>>>> to go bad. He said the old fluid is thicker than new & that may be
>>>> all the old MC needed to go. He replaced the MC & deducted the cost
>>>> of the fluid change he had just done($247 - $75= $172 for new MC
>>>> installed).
>>>> Anyone ever hear of new brake fluid pushing a 12 year old MC over
>>>> the edge?
>>>> Thanks,
>>>> Rich
>>>
>>>
>>>
>>>
>>> Nope, but a bleed done to full stroke certainly will.
>>>
>> Is it that a bleed should not be done to full stroke or are you saying
>> a normal brake bleed will cause an old MC to fail?
>> Thanks,
>> Rich
>
>
> personally, i don't put too much creedance in the "can't bleed full
> stroke" theory. i've bled master cylinders with pressure bleeders,
> /zero/ stroke, and still had seals disintegrate the next week. my
> opinion is that unless you change the fluid regularly, the fluid gets
> contaminated. this swells the rubbers. these swollen rubbers wear to
> fit the cylinder in the expanded state. when you change to fresh fluid,
> which contains rubber conditioners, the seals shrink slightly, and then
> they start leaking.
>
> bottom line, if the cylinder's given you 150k, you're doing just fine.
> change it, do another 150k. it's peanuts. next time, make sure you
> flush the brake fluid annually - i'll bet you it lasts a good deal longer.
>
I tend to believe that is what happened. I thought that I had changed
the fluid at least once before but upon checking of my records, it seems
that I never did. It seems the only thing the mechanic might have done
"wrong" was to not warn me of this possibility. Either way, a master
cylinder replacement was imminent either now or the next time I had
major brake work done which required bleeding.
Thanks for your expert assessment.
Rich