After car on jackstands, brakes are mushy.

  • Thread starter Thread starter Jamie
  • Start date Start date
J

Jamie

I had my 1987 740's front end up on jackstands for a few days. When I
lowered the car and went for a test drive the front brakes barely
worked. I drove the neighborhood pumping them and slowly they came
back.

First thing this morning they felt very mushy until I pumped them. I
inspected the brakes, pads and calipers a few weeks ago and they are
good.

Could having my cars front end jacked up have done something with the
brake fluid or system? My brakes have felt a little soft for the 6
months I've had the car, but never this bad. I don't see fluid anywhere
and was thinking it might be time to bleed the system and refill it.

Any suggestions?

Thanks,
JB
 
Jamie said:
I had my 1987 740's front end up on jackstands for a few days. When I
lowered the car and went for a test drive the front brakes barely
worked. I drove the neighborhood pumping them and slowly they came
back.

First thing this morning they felt very mushy until I pumped them. I
inspected the brakes, pads and calipers a few weeks ago and they are
good.
Click to expand...

My guess would be a failing master cylinder. If pumping up gets things
sort of working then that is probably the problem.

Jack stands is probably a coincidence.

John
 
I test drove it at lunch and here's what I found. If while driving I
fully depress the pedal, it will not begin to engage the brakes until I
am about 2/3 down. Pumping the brakes has no effect, the brakes do not
engage until around 2/3 depressed.

However, if I hold the pedal down about 2/3 and begin pumping the pedal
only the bottom 1/3 over and over, it grabs and grabs. So, as long as I
keep the pedal 2/3 depressed, I can repeatedly engage the brakes, it's
that first 2/3rds that do nothing and the bottom 1/3 doing all the
work.

Is that still a master cylinder, booster or air?
 
Exact same thing happened to me on my 1986 Toyota truck. Here's what
it was; The brake master cylinder 'O' rings had desintegrated, and
fluid started leaking into the brake booster, corroding the diagphram.
The back of the master cylinder is conveniently aimed so if it leaks it
goes right into the booster. I got a used booster and a rebuilt master
cylinder and it went back to normal, although I bled the crap out of
the brake system after that in case of contamination, and rebuilt the
rear wheel cylinders.

This is hard to see because the fluid goes into the brake booster, not
onto the ground. Brake fluid is corrosive, so it doesn't take much to
kill the internals of the booster. I didn't even notice that much of a
drop in fluid, I just thought it was the wheel cylinders leaking a
little, which I wasn't too worried about.

Having the front of the car raised may have simply let more than the
usual small amount of brake fluid into the booster, and killed it
excecutioner style...
 
Aha. That seems reasonable. I checked FCP Groton and they want about
$125 for a master cylinder. Not sure about a booster. Looks like I may
need to see about those.

Thanks!
 
Jamie said:
Aha. That seems reasonable. I checked FCP Groton and they want about
$125 for a master cylinder. Not sure about a booster. Looks like I may
need to see about those.
Click to expand...

Check you local auto parts stores as well. Sometimes with rebuildable
items it is easier and about the same cost to buy locally.

John
 
You must log in or register to reply here.
Back
Top