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G

·
Discussion Starter · #1 ·
My problem started a couple weeks ago. The ABS light came on, aprox
1/2 hour later my brakes were not working properly. The pedal felt
all wrong (goes all the way down with no pressure) and it sounded like
the breaks were intermittingly stopping (like skidding) when they did
work... very dangerous to drive this way.

I took the truck home and checked the fluid, it turns out the fluid is
low, so I replaced it, still no puddles in the driveway and from
checking the inside (quick look) and around the wheels no leaks.

I took it up to the garage where I bought the truck and the guys up
there (without looking at it) say it sounds like it need's a master
cylinder. What is your opinion? Is there anything else I should
check into before I buy a MC and try to install it myself? Any advise
about installing a Master Cylinder?

I bought this truck used and I really fell in love with it. I'd like
to do the repairs myself when possible, but I donot have a ton of
experience with this type of thing, so it is a learning process for
me. Any kind of insight will help!





Thank you
Kevin
 
G

·
Discussion Starter · #2 ·
"kevin" <[email protected]> wrote in message
news:[email protected]
>
> My problem started a couple weeks ago. The ABS light came on, aprox
> 1/2 hour later my brakes were not working properly. The pedal felt
> all wrong (goes all the way down with no pressure) and it sounded like
> the breaks were intermittingly stopping (like skidding) when they did
> work... very dangerous to drive this way.
>
> I took the truck home and checked the fluid, it turns out the fluid is
> low, so I replaced it, still no puddles in the driveway and from
> checking the inside (quick look) and around the wheels no leaks.
>
> I took it up to the garage where I bought the truck and the guys up
> there (without looking at it) say it sounds like it need's a master
> cylinder. What is your opinion? Is there anything else I should
> check into before I buy a MC and try to install it myself? Any advise
> about installing a Master Cylinder?
>
> I bought this truck used and I really fell in love with it. I'd like
> to do the repairs myself when possible, but I donot have a ton of
> experience with this type of thing, so it is a learning process for
> me. Any kind of insight will help!
>
>
>
>
>
> Thank you
> Kevin


Kevin,
Replacing a master cylinder is fairly easy. Its pretty much just a swap out
kind of deal. Just remember to prime the new master cylinder before you
install it. You do this by pushing the plunger rod in and out a couple of
times to get the air out of the primary and secondary plungers. Once you
have done that, just install in the reverse order that you took the old one
off, and bleed ALL of your brakes to get any air out of the system.
You also have a choice of brake bleeding styles. The most prominent one
is pressure bleeding. Have a friend pump the brakes 2-3 times, or until
solid. When your friend says they are solid, have your friend hold down on
the pedal, and open the bleed valve. Close the bleed valve BEFORE your
friends releases the brake pedal. Keep doing this until you get no more air
in the system, and watch your resevoir.. You have to keep fluid in it at all
times, or you have to start over.
The second style is the gravity bleed. Basically you just open the bleed
valve, and let the fluid drain out. This takes a long time, and again, you
have to keep an eye on the resevoir. Also with this system, you probably
only want to do one at a time. It might help speed up the process.
That's it, thats all you need to do. Oh, and one more thing. Buy a
chilton/haynes manual for your vehicle.. When it comes to repairs by a DIY,
or a professional. You can't beat a good tech manual.
 
G

·
Discussion Starter · #3 ·
"kevin" <[email protected]> wrote in message
news:[email protected]
>
> My problem started a couple weeks ago. The ABS light came on, aprox
> 1/2 hour later my brakes were not working properly. The pedal felt
> all wrong (goes all the way down with no pressure) and it sounded like
> the breaks were intermittingly stopping (like skidding) when they did
> work... very dangerous to drive this way.
>
> I took the truck home and checked the fluid, it turns out the fluid is
> low, so I replaced it, still no puddles in the driveway and from
> checking the inside (quick look) and around the wheels no leaks.
>
> I took it up to the garage where I bought the truck and the guys up
> there (without looking at it) say it sounds like it need's a master
> cylinder. What is your opinion? Is there anything else I should
> check into before I buy a MC and try to install it myself? Any advise
> about installing a Master Cylinder?
>
> I bought this truck used and I really fell in love with it. I'd like
> to do the repairs myself when possible, but I donot have a ton of
> experience with this type of thing, so it is a learning process for
> me. Any kind of insight will help!
>
>
>
>
>
> Thank you
> Kevin


Bad master cylinder. Internally the master cylinder has pistons and
cylinders that move in and out as you press and release the brake pedal.
The pistons and cylinders fit tightly together but, eventually, they wear
and as you step on the pedal, fluid leaks past the pistons causing the
brakes to not work properly and causing the pedal to feel strange. However,
because the leak is internal to the master cylinder, nothing will spill out
onto the ground for you to see.

Replacing the master cylinder is a simple swap-out. Find someone who has
done it, or, do a Google search for replacing master cylinder. The new one
will have plastic caps on the inlet and outlet ports. Open these caps and
fill the new master cylinder with fluid -- pump the rod in and out a few
times to prime the master cylinder with fluid. You'll still need to bleed
the brakes after replacing the master cylinder.
 
G

·
Discussion Starter · #4 ·
"kevin" <[email protected]> wrote in message
news:[email protected]
>
> My problem started a couple weeks ago. The ABS light came on, aprox
> 1/2 hour later my brakes were not working properly. The pedal felt
> all wrong (goes all the way down with no pressure) and it sounded like
> the breaks were intermittingly stopping (like skidding) when they did
> work... very dangerous to drive this way.
>
> I took the truck home and checked the fluid, it turns out the fluid is
> low, so I replaced it, still no puddles in the driveway and from
> checking the inside (quick look) and around the wheels no leaks.
>
> I took it up to the garage where I bought the truck and the guys up
> there (without looking at it) say it sounds like it need's a master
> cylinder. What is your opinion? Is there anything else I should
> check into before I buy a MC and try to install it myself? Any advise
> about installing a Master Cylinder?


How low was the reservoir? It may take more than a "quick look" to find the
leaking component. Until you determine where the fluid went, all we can do
is speculate.

Dave
 
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Discussion Starter · #5 ·
On Fri, 20 Jan 2006 20:34:07 -0600, "Hairy" <[email protected]> wrote:

>
>"kevin" <[email protected]> wrote in message
>news:[email protected]
>>
>> My problem started a couple weeks ago. The ABS light came on, aprox
>> 1/2 hour later my brakes were not working properly. The pedal felt
>> all wrong (goes all the way down with no pressure) and it sounded like
>> the breaks were intermittingly stopping (like skidding) when they did
>> work... very dangerous to drive this way.
>>
>> I took the truck home and checked the fluid, it turns out the fluid is
>> low, so I replaced it, still no puddles in the driveway and from
>> checking the inside (quick look) and around the wheels no leaks.
>>
>> I took it up to the garage where I bought the truck and the guys up
>> there (without looking at it) say it sounds like it need's a master
>> cylinder. What is your opinion? Is there anything else I should
>> check into before I buy a MC and try to install it myself? Any advise
>> about installing a Master Cylinder?

>
>How low was the reservoir? It may take more than a "quick look" to find the
>leaking component. Until you determine where the fluid went, all we can do
>is speculate.


I had a Toyota truck that slowly lost it's master cylinder. No
evidence of fluid leaks anywhere but all symptoms pointed to the
master cylinder. Only when I replaced it did I discover where the
fluid went... Into the vacuum booster and down the inside of the
firewall where it saturated the carpet pad.. Never noticed because of
the rubber floor mats I had down.
 
G

·
Discussion Starter · #6 ·

> >
> >How low was the reservoir? It may take more than a "quick look" to find

the
> >leaking component. Until you determine where the fluid went, all we can

do
> >is speculate.

>
> I had a Toyota truck that slowly lost it's master cylinder. No
> evidence of fluid leaks anywhere but all symptoms pointed to the
> master cylinder. Only when I replaced it did I discover where the
> fluid went... Into the vacuum booster and down the inside of the
> firewall where it saturated the carpet pad.. Never noticed because of
> the rubber floor mats I had down.
>


That is exactly my point. Brake fluid doesn't just suddenly disappear for no
reason. If you lose fluid, there's a leak somewhere. It's just a matter of
finding it.

Dave
 
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Discussion Starter · #7 ·
Just because the fluid level is low doesn't mean there is a leak

If your brake pads and shoes are worn down to the minimum your fluid level
will be on min.
Nowhere in your post do you say how your pads or shoes are

With your rear shoes down to minimum and a sloppy adjuster your pedal will
go to the floor

Isn't it time you have somebody have a look at it who knows what he/she's
doing

After all , THERE YOUR BRAKES


"kevin" <[email protected]> wrote in message
news:[email protected]
>
> My problem started a couple weeks ago. The ABS light came on, aprox
> 1/2 hour later my brakes were not working properly. The pedal felt
> all wrong (goes all the way down with no pressure) and it sounded like
> the breaks were intermittingly stopping (like skidding) when they did
> work... very dangerous to drive this way.
>
> I took the truck home and checked the fluid, it turns out the fluid is
> low, so I replaced it, still no puddles in the driveway and from
> checking the inside (quick look) and around the wheels no leaks.
>
> I took it up to the garage where I bought the truck and the guys up
> there (without looking at it) say it sounds like it need's a master
> cylinder. What is your opinion? Is there anything else I should
> check into before I buy a MC and try to install it myself? Any advise
> about installing a Master Cylinder?
>
> I bought this truck used and I really fell in love with it. I'd like
> to do the repairs myself when possible, but I donot have a ton of
> experience with this type of thing, so it is a learning process for
> me. Any kind of insight will help!
>
>
>
>
>
> Thank you
> Kevin
>
 
G

·
Discussion Starter · #8 ·
On Fri, 20 Jan 2006 20:53:19 -0700, "JohanB"
<[email protected]> wrote:

>Just because the fluid level is low doesn't mean there is a leak
>
>If your brake pads and shoes are worn down to the minimum your fluid level
>will be on min.
>Nowhere in your post do you say how your pads or shoes are
>
>With your rear shoes down to minimum and a sloppy adjuster your pedal will
>go to the floor
>
>Isn't it time you have somebody have a look at it who knows what he/she's
>doing
>
>After all , THERE YOUR BRAKES
>


I appreciate all the advice and it really does help.
Unfortunately I can only do a little at a time, so yes this weekend I
need to check the pads as well as the other suggestions that have been
made. I want to rule out every possibility before I replace the
master cylinder.

I understand your feeling (re have a pro do it), but I like this
truck and want to learn everything I can regarding it's repair and
upkeep Im no mechanic but I need to start somewhere. I am not going
to learn anything if I bring it someplace and have it done for me.
Fortunately I have some free time and I can keep the truck off the
road so I have the luxury of learning as I go. Luckily I you guys
have taken the time to point me in right direction too.






Thanks
Kevin
 
G

·
Discussion Starter · #9 ·
OK, check the thickness of your front pads and rotors, as well as the rear
shoes and drum diameter and report back


"kevin" <[email protected]> wrote in message
news:[email protected]
> On Fri, 20 Jan 2006 20:53:19 -0700, "JohanB"
> <[email protected]> wrote:
>
> >Just because the fluid level is low doesn't mean there is a leak
> >
> >If your brake pads and shoes are worn down to the minimum your fluid

level
> >will be on min.
> >Nowhere in your post do you say how your pads or shoes are
> >
> >With your rear shoes down to minimum and a sloppy adjuster your pedal

will
> >go to the floor
> >
> >Isn't it time you have somebody have a look at it who knows what he/she's
> >doing
> >
> >After all , THERE YOUR BRAKES
> >

>
> I appreciate all the advice and it really does help.
> Unfortunately I can only do a little at a time, so yes this weekend I
> need to check the pads as well as the other suggestions that have been
> made. I want to rule out every possibility before I replace the
> master cylinder.
>
> I understand your feeling (re have a pro do it), but I like this
> truck and want to learn everything I can regarding it's repair and
> upkeep Im no mechanic but I need to start somewhere. I am not going
> to learn anything if I bring it someplace and have it done for me.
> Fortunately I have some free time and I can keep the truck off the
> road so I have the luxury of learning as I go. Luckily I you guys
> have taken the time to point me in right direction too.
>
>
>
>
>
>
> Thanks
> Kevin
>
>
>
 
G

·
Discussion Starter · #10 ·
On Sat, 21 Jan 2006 08:50:16 -0700, "JohanB"
<[email protected]> wrote:

>OK, check the thickness of your front pads and rotors, as well as the rear
>shoes and drum diameter and report back



I did and everything is fine, infact I wont have to worry about
replacing anything for another year. I also re-checked the brake
fluid and it has remained at the same level (since I replaced it,
altho Ive driven only 2 miles aside from the driveway to garage and
back a couple times since I refilled it) , so I believe this indicates
a master cylinder prob right? I've checked everywhere (including the
firewall which someone sugg today) for any possible signs of leakage
and nothing. If the MC goes is it possible for the fluid to get low
and then no further leaking?

I've pretty much run out of things to do except replace the MC or is
there something else Im overlooking?






thanks
Kevin
 
G

·
Discussion Starter · #11 ·
If all brakes are fine and no external leaks it could only be internal leak
in master cylinder or really bad adjusted rear brakes

But still, why was the fluid low ???

Fluid low can only mean 2 things

The brakes aren't as good as you are telling us and worn out or external
leak.




"kevin" <[email protected]> wrote in message
news:[email protected]
> On Sat, 21 Jan 2006 08:50:16 -0700, "JohanB"
> <[email protected]> wrote:
>
> >OK, check the thickness of your front pads and rotors, as well as the

rear
> >shoes and drum diameter and report back

>
>
> I did and everything is fine, infact I wont have to worry about
> replacing anything for another year. I also re-checked the brake
> fluid and it has remained at the same level (since I replaced it,
> altho Ive driven only 2 miles aside from the driveway to garage and
> back a couple times since I refilled it) , so I believe this indicates
> a master cylinder prob right? I've checked everywhere (including the
> firewall which someone sugg today) for any possible signs of leakage
> and nothing. If the MC goes is it possible for the fluid to get low
> and then no further leaking?
>
> I've pretty much run out of things to do except replace the MC or is
> there something else Im overlooking?
>
>
>
>
>
>
> thanks
> Kevin
 
G

·
Discussion Starter · #12 ·
On Sat, 21 Jan 2006 15:15:17 -0700, "JohanB"
<[email protected]> wrote:

>If all brakes are fine and no external leaks it could only be internal leak
>in master cylinder or really bad adjusted rear brakes
>
>But still, why was the fluid low ???
>
>Fluid low can only mean 2 things
>
>The brakes aren't as good as you are telling us and worn out or external
>leak.



could the internal leak in the MC have caused the fluid to be low?
Wouldnt that explain why it does not appear to be leaking now?
 
G

·
Discussion Starter · #13 ·
"kevin" <[email protected]> wrote in message
news:[email protected]
> On Sat, 21 Jan 2006 15:15:17 -0700, "JohanB"
> <[email protected]> wrote:
>
>>If all brakes are fine and no external leaks it could only be internal
>>leak
>>in master cylinder or really bad adjusted rear brakes
>>
>>But still, why was the fluid low ???
>>
>>Fluid low can only mean 2 things
>>
>>The brakes aren't as good as you are telling us and worn out or external
>>leak.

>
>
> could the internal leak in the MC have caused the fluid to be low?
> Wouldnt that explain why it does not appear to be leaking now?
>
>

Kevin,
An internal leak in the MC will NOT cause fluid to go low. The reason for
this is because the brake system is hydraulic and has a finite amount of
room. IF there is no external leak, then the fluid should not go down,
EXCEPT for wear on the brake pads and shoes.

As for a bad MC, it will feel spongy, but then fall to the floor slowly. Now
the ABS light will come on if the resevoir gets low. Thats because the
resevoir indicator will signal the ABS and turn the ABS off in case it
completely drains out. This protects the ABS from burning up because it
doesnt have fluid in it.

I say check your brake cylinders on the rear again. Just to make sure of no
leakage. In fact I would wipe them out with a rag, and then check them again
after a few miles of driving. But if your brake pedal feels like what I have
described above, then I suggest a new master cyliner anyway.

I am ASE certified for brakes. ASE # OP3GR7RM1KURTZ You can verify this
number with ASE through their website I believe.
Pk
 
G

·
Discussion Starter · #14 ·
internal leaks will only cause a pressure loss and make the pedal feel
spongy or drop to floor.

no loss off fluid


"kevin" <[email protected]> wrote in message
news:[email protected]
> On Sat, 21 Jan 2006 15:15:17 -0700, "JohanB"
> <[email protected]> wrote:
>
> >If all brakes are fine and no external leaks it could only be internal

leak
> >in master cylinder or really bad adjusted rear brakes
> >
> >But still, why was the fluid low ???
> >
> >Fluid low can only mean 2 things
> >
> >The brakes aren't as good as you are telling us and worn out or external
> >leak.

>
>
> could the internal leak in the MC have caused the fluid to be low?
> Wouldnt that explain why it does not appear to be leaking now?
>
>
 
G

·
Discussion Starter · #15 ·
That's about what my problem is... However, I believe mine is actually
being sucked into the engine a little bit at a time. One of these
days.......!


"The OTHER Kevin in San Diego" <skiddz "AT" adelphia "DOT" net> wrote in
message news:[email protected]
> On Fri, 20 Jan 2006 20:34:07 -0600, "Hairy" <[email protected]> wrote:
>
>>
>>"kevin" <[email protected]> wrote in message
>>news:[email protected]
>>>
>>> My problem started a couple weeks ago. The ABS light came on, aprox
>>> 1/2 hour later my brakes were not working properly. The pedal felt
>>> all wrong (goes all the way down with no pressure) and it sounded like
>>> the breaks were intermittingly stopping (like skidding) when they did
>>> work... very dangerous to drive this way.
>>>
>>> I took the truck home and checked the fluid, it turns out the fluid is
>>> low, so I replaced it, still no puddles in the driveway and from
>>> checking the inside (quick look) and around the wheels no leaks.
>>>
>>> I took it up to the garage where I bought the truck and the guys up
>>> there (without looking at it) say it sounds like it need's a master
>>> cylinder. What is your opinion? Is there anything else I should
>>> check into before I buy a MC and try to install it myself? Any advise
>>> about installing a Master Cylinder?

>>
>>How low was the reservoir? It may take more than a "quick look" to find
>>the
>>leaking component. Until you determine where the fluid went, all we can do
>>is speculate.

>
> I had a Toyota truck that slowly lost it's master cylinder. No
> evidence of fluid leaks anywhere but all symptoms pointed to the
> master cylinder. Only when I replaced it did I discover where the
> fluid went... Into the vacuum booster and down the inside of the
> firewall where it saturated the carpet pad.. Never noticed because of
> the rubber floor mats I had down.
>
>
 
G

·
Discussion Starter · #16 ·
"Shayne" <[email protected]> wrote in message
news:[email protected]
> That's about what my problem is... However, I believe mine is actually
> being sucked into the engine a little bit at a time. One of these
> days.......!
>



Shayne,
I dont know if you have noticed, but there is a reason that the vacuum line
on the brake booster is located at the top of the booster. Your truck can
not suck the brake fluid into the engine by way of the vacuum. If it is
going anywhere, its just staying in the brake booster, or leaking down the
firewall. I would prefer to say that it is staying in the brake booster,
especially if you havent had to add more than a few ounces of fluid. The
vacuum side of the booster is sealed, so as to hold the vacuum, the only
place for the fluid to get out of the vacuum side and into the passenger
compartment is through a valve in the center of the diaphram on the booster,
and that would require several ounces of fluid to achieve that, also it
would require almost a half gallon of DOT3 fluid to fill the booster enough
for the engine to suck it back into the engine.

Pk
 
G

·
Discussion Starter · #17 ·
On Sat, 21 Jan 2006 21:18:41 -0600, "pkurtz2" <[email protected]> wrote:

>
>"kevin" <[email protected]> wrote in message
>news:[email protected]
>> On Sat, 21 Jan 2006 15:15:17 -0700, "JohanB"
>> <[email protected]> wrote:
>>
>>>If all brakes are fine and no external leaks it could only be internal
>>>leak
>>>in master cylinder or really bad adjusted rear brakes
>>>
>>>But still, why was the fluid low ???
>>>
>>>Fluid low can only mean 2 things
>>>
>>>The brakes aren't as good as you are telling us and worn out or external
>>>leak.

>>
>>
>> could the internal leak in the MC have caused the fluid to be low?
>> Wouldnt that explain why it does not appear to be leaking now?
>>
>>

>Kevin,
>An internal leak in the MC will NOT cause fluid to go low. The reason for
>this is because the brake system is hydraulic and has a finite amount of
>room. IF there is no external leak, then the fluid should not go down,
>EXCEPT for wear on the brake pads and shoes.
>
>As for a bad MC, it will feel spongy, but then fall to the floor slowly. Now
>the ABS light will come on if the resevoir gets low. Thats because the
>resevoir indicator will signal the ABS and turn the ABS off in case it
>completely drains out. This protects the ABS from burning up because it
>doesnt have fluid in it.
>
>I say check your brake cylinders on the rear again. Just to make sure of no
>leakage. In fact I would wipe them out with a rag, and then check them again
>after a few miles of driving. But if your brake pedal feels like what I have
>described above, then I suggest a new master cyliner anyway.
>
>I am ASE certified for brakes. ASE # OP3GR7RM1KURTZ You can verify this
>number with ASE through their website I believe.
>Pk
>




Thanks I am definetly going to take your advice and do a thorough
check of everything later this week or this weekend. So what you are
saying is there has to be a leak someplace? Can you answer one more
question, is there anything special I need to do or any special tool I
need to bleed the brakes when I replace the MC?





Thanks
Kevin
 
G

·
Discussion Starter · #18 ·
> Thanks I am definetly going to take your advice and do a thorough
> check of everything later this week or this weekend. So what you are
> saying is there has to be a leak someplace?

If you havent noticed a significant drop in fluid level, then I doubt you
have a leak. That is to say that if you check your fluids once a week, and
its taken a month or two (dependent on driving conditions, and how often you
use your brakes) for the level to drop, then its not a leak, its going down
due to use. If this is the case, it should not be refilled, but the front
pads probably need replaced cause they are worn. As you use your brakes, on
a truck its typically a 60/40 frt/rear ratio, the pistons have to slide out
to make up the space between your rotor and the pad. This is done so that
the next time you hit your brakes, they react quickly, and not take 2-3 sec
to contact the rotor. There is a square o-ring on the piston that will pull
the piston away from the rotor about 2MM. The reason you see the brake fluid
go down is because its in the piston on your brakes. The rear brakes act
differently, and wear on them wont be noticed by a loss of fluid in the
resevoir. Their slack is actually taken up by a mechanical slack adjuster
installed in each rear drum, UNLESS you have 4-wheel disc brakes. Then it
will act the same as the front. As a rule of thumb, I change my rear shoes
every 3rd time I change the fronts. More so if I haul heavy loads. It
depends on how much wear they get. My bet is that your frt pads are sitting
about an 1/8 to 3/16 of an inch off your rotors and this is what caused the
fluid to go down. If that is the case, its time for new pads on the front.

> Can you answer one more question, is there anything special I need to do
> or any special tool I
> need to bleed the brakes when I replace the MC?

*** IF YOU HAVE 4 WHEEL ABS, TAKE IT TO THE SHOP****
No special tools unless you have 4 wheel ABS. If you have RABS (Rear ABS)
only, then you can do this at home. Definitely get a tech manual for the
vehicle you are working on. I have my tech manual for 93-00 Rangers in front
of me, and it adimently states NOT to do this if you have 4 wheel ABS. Do
make sure you pump that piston a couple times with fluid in the resevoir
before you install it, this just primes it and gets the air out of the MC..
If you have RABS, then there is a special procedure to bleed the air out of
it. You have to bleed the ABS pump as well as the other 4 brakes. Buy the
Haynes Tech manual if you havent done so. This is all covered in Chpt 9,
under Brakes. But I cant say it enough, if you have 4 wheel ABS dont do
this. In the end you will have to have it towed to the shop to get the ABS
bled. It requires an expensive special tool, that would not be worth you
buying it. If you arent sure if you have 4wheel ABS, dont do this.
>
> Thanks
> Kevin



I
 
G

·
Discussion Starter · #19 ·
On Mon, 23 Jan 2006 22:03:06 -0600, "pkurtz2" <[email protected]> wrote:

>> Thanks I am definetly going to take your advice and do a thorough
>> check of everything later this week or this weekend. So what you are
>> saying is there has to be a leak someplace?

>If you havent noticed a significant drop in fluid level, then I doubt you
>have a leak. That is to say that if you check your fluids once a week, and
>its taken a month or two (dependent on driving conditions, and how often you
>use your brakes) for the level to drop, then its not a leak, its going down
>due to use. If this is the case, it should not be refilled, but the front
>pads probably need replaced cause they are worn. As you use your brakes, on
>a truck its typically a 60/40 frt/rear ratio, the pistons have to slide out
>to make up the space between your rotor and the pad. This is done so that
>the next time you hit your brakes, they react quickly, and not take 2-3 sec
>to contact the rotor. There is a square o-ring on the piston that will pull
>the piston away from the rotor about 2MM. The reason you see the brake fluid
>go down is because its in the piston on your brakes. The rear brakes act
>differently, and wear on them wont be noticed by a loss of fluid in the
>resevoir. Their slack is actually taken up by a mechanical slack adjuster
>installed in each rear drum, UNLESS you have 4-wheel disc brakes. Then it
>will act the same as the front. As a rule of thumb, I change my rear shoes
>every 3rd time I change the fronts. More so if I haul heavy loads. It
>depends on how much wear they get. My bet is that your frt pads are sitting
>about an 1/8 to 3/16 of an inch off your rotors and this is what caused the
>fluid to go down. If that is the case, its time for new pads on the front.
>
>> Can you answer one more question, is there anything special I need to do
>> or any special tool I
>> need to bleed the brakes when I replace the MC?

> *** IF YOU HAVE 4 WHEEL ABS, TAKE IT TO THE SHOP****
>No special tools unless you have 4 wheel ABS. If you have RABS (Rear ABS)
>only, then you can do this at home. Definitely get a tech manual for the
>vehicle you are working on. I have my tech manual for 93-00 Rangers in front
>of me, and it adimently states NOT to do this if you have 4 wheel ABS. Do
>make sure you pump that piston a couple times with fluid in the resevoir
>before you install it, this just primes it and gets the air out of the MC..
>If you have RABS, then there is a special procedure to bleed the air out of
>it. You have to bleed the ABS pump as well as the other 4 brakes. Buy the
>Haynes Tech manual if you havent done so. This is all covered in Chpt 9,
>under Brakes. But I cant say it enough, if you have 4 wheel ABS dont do
>this. In the end you will have to have it towed to the shop to get the ABS
>bled. It requires an expensive special tool, that would not be worth you
>buying it. If you arent sure if you have 4wheel ABS, dont do this.
>>
>> Thanks
>> Kevin

>
>
> I
>



Thanks so much, your detailed reply really helps. I am lucky enough
to have access to a bay at a local garage on saturday so I will be
able to check all this easily. I really appreciate you explaining
how the system works.

So if you are right about the pads, why would the master cylinder and
the brakes seemingly go all at once?? One minute I am pulling into a
gas station and I notice the ABS light, aprox 10 minutes later the
brake's are spongy and Im barely getting any braking at all??!?? Is
this commen for your pads and MC to go at the same time?





thanks again,

Kevin
 
G

·
Discussion Starter · #20 ·
> Thanks so much, your detailed reply really helps. I am lucky enough
> to have access to a bay at a local garage on saturday so I will be
> able to check all this easily. I really appreciate you explaining
> how the system works.
>
> So if you are right about the pads, why would the master cylinder and
> the brakes seemingly go all at once?? One minute I am pulling into a
> gas station and I notice the ABS light, aprox 10 minutes later the
> brake's are spongy and Im barely getting any braking at all??!?? Is
> this commen for your pads and MC to go at the same time?
>
>
>
>
>
> thanks again,
>
> Kevin
>


It sounds like you had a sticking piston, and when it finally came loose and
moved out in its bore, it was enough to pull the fluid level down in the
system. That stuck piston coming loose might have allowed the plunger to
travel down the bore farther in the MC to a spot that was getting rusty
(DOT3 brake fluid is moisture absorbent, thats why its in plastic bottles,
and is supposed to stay sealed to keep moisture out). The rust could have
possibly knicked the rubber seal, and created a leak in the MC plunger
seals.Also, alot of pluger seals, are cup seals, so when the have pressure
against them, they spread out to hold the fluid in the system, if one came
loose.... Again, who knows how it happens, and there are several ways it can
happen, and to really find out what did happen you would have to disassemble
the MC and inspect the parts, but suffice it to say. If the MC goes out, you
dont want to have to stop too fast..
 
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