brake master cylinder (Page 1/1)
jim94 MAR 28, 10:42 PM
all i wanted to do is put something in the front of my car and all i seen was brake fluid all over the place. to people who do not know how to put a cap back on, donot touch cars for a living. the gasket was sucked in the with the two round thinks stuck in the valleys where there should be fluid. i would think when checking the fluid you can see thru the side being it is see thru plastic. i you do remove the top and the seal does not come with it, when installing it the seal should be in the top and everything should be flush. Or would steping in the brake pedal suck the seal in the master.? i am not sure but the front compartment is very clean now.
fieroguru MAR 29, 08:09 AM
Not real sure what your question is...

When reinstalling the brake master cover, flatten the black seal, fit it over the cap, then place the cap on the master cylinder reservoir.

When the brake pads wear, the caliper pistons extend and remain extended. This means more brake fluid will be stored at the calipers and less in the master, which will cause the extendable portion of the black seal to protrude down into the master reservoir. When this happens (with the cap on) the level of the fluid will remain at the same point through the sight glass, but there will be less fluid (extension of the seal is displacing the fluid). This whole process is to allow for the fluid to move around in the system w/o being exposed to air and moisture.

If you pull the cap and seal and find the black seal fully extended or see low fluid level in the reservoir, then there is either a leak in the system or your brake pads have significant wear.

[This message has been edited by fieroguru (edited 03-29-2019).]

jim94 MAR 29, 09:59 AM
i have half pad left on all 4 wheels with no leaks any where. i installed the seal and top on corecttly. you can hear the sucking soundof a good seal. went for a ride and had no leaks.
cvxjet MAR 29, 10:17 AM
The cap seal will come off and stay on the MC.... When it does this, pull it off the MC and reinstall it in the cap. The four tabs should fit in the notches in the cap which keeps the seal in place while snapping the cap on.....(I drove over mt. Hamilton (Lick observatory) once and the seal was not.....sealed- Yes, it "cleaned up" my front compartment")

Over a long period of time, the two extendable portions will extend a bit....That is normal......but as Fieroguru pointed out, if they extend a bunch over a short amount of time, then you have a leak in the system......Either way, carefully push the two extensions back up into the cap so they can compensate normally for fluid lose/piston extension...
theogre MAR 29, 01:29 PM
Caution:
If you fill a MC and the pads are worn then often need to suck some out of MC before replacing them!
If you don't then fluid will get forced out when caliper Pistons are pushed in and in many GM vehicle will pop the MC cover and seal. Can have Fluid spray all over the place.

Every time the tank is open carefully check the rubber. Any damage then Replace the rubber.
Then you should "flatten" the rubber, fill the tanks then close the tank.
Why? You don't want air in the tank or you will have "Wet" Fluid and likely fast and far lower boil point as listed on Fluid Labels.
See my Cave, Brake Fluid

In fact if the tank is open for a day or more... Likely the Fluid is Very Wet and can boil close to plane water. I've test some old bottles and Used or New but Seal broken doesn't matter and test boil points low as ~ 220°F.

------------------
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(Jurassic Park)

The Ogre's Fiero Cave

jim94 MAR 29, 08:50 PM
my car has had a new clutch installed in december.thanks for your info, very helpfull. i have a new seal coming from the fiero store.question answered, jim
jim94 APR 08, 10:23 PM
i replaced the master cylinder seal and i must say the brake pedal feels so much better. the new one was a dorman from the fiero store and much stiffer than the old one. after 9 yrs i let my wife drive my car. she was happy, she said i still have it.she missess her 5 speed turbo dodge daytona.