sporadic brake problem - pedal sinks to floor

Occasionally (when it's warm and I'm in a traffic jam) my brake pedal will
slowly sink to the floor. It will still give good stopping power when
pressed quickly, but for a long application I have to re-depress the pedal.

Is this a vacuum problem?

Thanks for any advise,
--Art
(91 Integra -- hope it's all right to ask here as I don't get the Acura
newsgroups)

 

|Occasionally (when it's warm and I'm in a traffic jam) my brake pedal will
|slowly sink to the floor. It will still give good stopping power when
|pressed quickly, but for a long application I have to re-depress the pedal.
|
|Is this a vacuum problem?

Nope, it's a master cylinder problem. The seals are letting the brake fluid
bypass. Hard pressure forces the seals up against the cylinder and makes them
seal. Light pressure lets it leak.
Replace the master cylinder.

|(91 Integra -- hope it's all right to ask here as I don't get the Acura
|newsgroups)

That's one o' them furrin cars, right?
Rex in Fort Worth

 

(Rex B) spake unto the masses in

Yup! MC seals are bad. Open up that piggy bank.


And to keep your new master cylinder new, get your fluid changed once a
year, preferably by the pedal-pump method.

 

Thanks guys -- good help in this group. I don't think I'd leave even if my
ISP started carrying the Acura group. I already need to replace the pads in
the back so I guess now I can do both at once. Anyone see a problem with
using the 1st (and cheapest) cylinder listed below. It says it comes with a
bleeder kit, which I assume means it comes with a couple of hoses to direct
fluid back to the reservoir. I'm not crazy about the name (Car-done). I'd
buy something with a price suggesting quality, but too many things are going
bad on this car leading me to believe it wasn't built to last. What about
Wearever brake pads -- something tells me they don't.

--Art
BTW Tegger, I'm posting a follow-up to "Re: overheating at idle" that I hope
you'll see.

Cardone 112544
Remanufactured; w/o ABS
Lifetime Limited Warranty Ships in 1 day
Weight: 3 lbs.
$45.88
$50.00 core

Bendix 12445
New; 1"; 4 Door; w/o ABS; 4 Wheel Disc Brakes
1 Year Replacement Warranty Ships in 1 day
Weight: 3 lbs.
$83.28

Beck/Arnley 0728686
Brake Master Cyl: w/o ABS; Cap & sensor not included
Lifetime Limited Warranty Ships in 1 day
Weight: 3.1 lbs.
$102.99

Tru Torque M39884
New; w/Reservoir; Power Front Disc Brakes w/o ABS; 15/16" Dia. Bore
Lifetime Replacement Warranty Ships in 1 day
Weight: 3.1 lbs.
$77.88

Raybestos MC39884
Master Cylinder w/Power: Exc. ABS
Lifetime Limited Warranty Ships in 1 day
Weight: 3.5 lbs.
$111.99

Raybestos 2539884
Master Cylinder: Raymold
Lifetime Limited Warranty Ships in 1 day
Weight: 3 lbs.
$85.99

Raybestos 2539884
Raymold Master Cylinder w/Power: Exc. ABS
Lifetime Limited Warranty Ships in 1 day
Weight: 3 lbs.
$85.99

This list comes from
http://www.partsamerica.com/SelectParts.asp?PartType=230&PTSet=A&SearchFor=M
aster%20Cylinder

 

Is it feasible to rebuild the MC? I've done it a couple of times, but
not recently and not on cars with ABS.

 

get the cardone. a-1 cardone is one of the biggest reman companies
out there. i've got 21 years on my cardone reman. and about 200,000
miles.
Chip

 

Thanks for the advise, Chip. I certainly can't pass on the price. I suppose
that even if a rebuild kit was available it wouldn't be worth the small
price difference.

--Art

 

On 31 Dec 2003 17:50:40 -0800, (Chip Stein) wrote:

|>
|> Is it feasible to rebuild the MC? I've done it a couple of times, but
|> not recently and not on cars with ABS.
|
|
| get the cardone. a-1 cardone is one of the biggest reman companies
|out there. i've got 21 years on my cardone reman. and about 200,000
|miles.

I run a Cardone reman MC on my RX7 road racing car.
4 seasons, no problems
Rex in Fort Worth

 

Never do that!!! Old fluid should be redirected to a container for
disposal. NEVER put anything but fresh fluid into the master cylinder
reservoir.

 

I think he meant for "bench bleeding" the reservoir... before hooking it up
to the system lines.

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

 

Makes sense. Lines long enough to reach from the wheels to the MC _would_
have to be terribly long, wouldn't they?

 

This almost always indicates worn master cylinder seals.

John

 

I have seen this on cars with leaking calipers and wheel cylinders, but
usually it is the MC seals.