Problems after replacing master cylinder
Mark
I have a lexus es300 with 128K miles. I had taken my car to the
mechanic as I felt the brakes needed work. I had to press the brake
pedal all the way down to stop the car. The mechanic suggested
replacing the master cylinder which I did.
Now, I have 2 unique problems and I am looking for advice here to
educate myself before I take the car back to the mechanic.
1. The brake pedal sometimes works just by a little pressing, and
other times I need to press it all the way down. In other words,
sometimes it brakes just by a slight touch of the foot and sometimes
it doesn't. The brakes work, just that the "firmness" of the pedal
keeps changing.
2. The car starts vibrating after driving for about 10 minutes on the
highway. The vibration doesn't start right away. There is vibration in
the car and the steering. When I brake, I get the pulsating feeling
with the brake pedal. All the passengers in the car can feel the
vibration. After about 15 minutes of driving, the vibration goes away
and doesn't come back during the same ride. If I park the car, let it
cool and drive again, then the same pattern repeats.
Could the experts here give some insight into what the possible issues
could be? The advice here has always helped me in the past and look
forward to your opinion.
Thanks and regards,
Mark
jim beam
> Hi,
>
> I have a lexus es300 with 128K miles. I had taken my car to the
> mechanic as I felt the brakes needed work. I had to press the brake
> pedal all the way down to stop the car. The mechanic suggested
> replacing the master cylinder which I did.
>
> Now, I have 2 unique problems and I am looking for advice here to
> educate myself before I take the car back to the mechanic.
>
> 1. The brake pedal sometimes works just by a little pressing, and
> other times I need to press it all the way down. In other words,
> sometimes it brakes just by a slight touch of the foot and sometimes
> it doesn't. The brakes work, just that the "firmness" of the pedal
> keeps changing.
sounds like air in the system. needs to be bled by someone that knows
what they're doing - your previous "mechanic" clearly doesn't.
>
> 2. The car starts vibrating after driving for about 10 minutes on the
> highway. The vibration doesn't start right away. There is vibration in
> the car and the steering. When I brake, I get the pulsating feeling
> with the brake pedal. All the passengers in the car can feel the
> vibration. After about 15 minutes of driving, the vibration goes away
> and doesn't come back during the same ride. If I park the car, let it
> cool and drive again, then the same pattern repeats.
remove wheels, scrape all rust from the wheel mounting surfaces on brake
disk. apply a LITTLE antiseize, making sure you get none on the disk,
then re-fit the wheel with bolts being torqued with a proper torque
wrench, in a two-stage sequence, and in the proper order.
>
> Could the experts here give some insight into what the possible issues
> could be? The advice here has always helped me in the past and look
> forward to your opinion.
>
> Thanks and regards,
> Mark
--
nomina rutrum rutrum
Tegger
0671bd...@w17g2000yqj.googlegroups.com:
> Hi,
>
> I have a lexus es300 with 128K miles.
What year?
Does it have ABS?
--
Tegger
Mark
> Mark <muff...@hotmail.com> wrote in news:e52c66b9-90a0-4583-a493-
> 0671bdd93...@w17g2000yqj.googlegroups.com:
>
> > Hi,
>
> > I have a lexus es300 with 128K miles.
>
> What year?
>
> Does it have ABS?
>
> --
> Tegger
Sorry, should have mentioned in my post. It is a '97 es300, and yes it
does ABS.
Paul
> Hi,
>
> I have a lexus es300 with 128K miles. I had taken my car to the
> mechanic as I felt the brakes needed work. I had to press the brake
> pedal all the way down to stop the car. The mechanic suggested
> replacing the master cylinder which I did.
>
> Now, I have 2 unique problems and I am looking for advice here to
> educate myself before I take the car back to the mechanic.
>
> 1. The brake pedal sometimes works just by a little pressing, and
> other times I need to press it all the way down. In other words,
> sometimes it brakes just by a slight touch of the foot and sometimes
> it doesn't. The brakes work, just that the "firmness" of the pedal
> keeps changing.
I would suspect a bad vac booster - assuming it has normal
vac boosted brakes and not boosted by power steering pump.
> 2. The car starts vibrating after driving for about 10 minutes on the
> highway. The vibration doesn't start right away. There is vibration in
> the car and the steering. When I brake, I get the pulsating feeling
> with the brake pedal. All the passengers in the car can feel the
> vibration. After about 15 minutes of driving, the vibration goes away
> and doesn't come back during the same ride. If I park the car, let it
> cool and drive again, then the same pattern repeats.
Could be tire(s) flat spotting when they sit.
Could also be loose / worn suspension or steering parts.
jim
lugnut wrote:
>
> On Mon, 5 Apr 2010 18:33:16 -0700 (PDT), Mark
> <muf...@hotmail.com> wrote:
>
> >Hi,
> >
> >I have a lexus es300 with 128K miles. I had taken my car to the
> >mechanic as I felt the brakes needed work. I had to press the brake
> >pedal all the way down to stop the car. The mechanic suggested
> >replacing the master cylinder which I did.
> >
> >Now, I have 2 unique problems and I am looking for advice here to
> >educate myself before I take the car back to the mechanic.
> >
> >1. The brake pedal sometimes works just by a little pressing, and
> >other times I need to press it all the way down. In other words,
> >sometimes it brakes just by a slight touch of the foot and sometimes
> >it doesn't. The brakes work, just that the "firmness" of the pedal
> >keeps changing.
> >
> >2. The car starts vibrating after driving for about 10 minutes on the
> >highway. The vibration doesn't start right away. There is vibration in
> >the car and the steering. When I brake, I get the pulsating feeling
> >with the brake pedal. All the passengers in the car can feel the
> >vibration. After about 15 minutes of driving, the vibration goes away
> >and doesn't come back during the same ride. If I park the car, let it
> >cool and drive again, then the same pattern repeats.
This part sounds like a stuck caliper. What happens is when you apply
the brakes, the pressure is being applied to only one side of the rotor
because the caliper can't move freely. That means even the tiniest
amount of run out in the rotor causes pulsation. If the caliper weren't
stuck it would float with the sideways movement of the rotor. If the
caliper can move freely a small amount of runout wouldn't cause
pulsation.
It also sounds like when things get warmed up the problem disappears.
That would mean the problem is related to temperature. If your
description is accurate as things start to warm up the problem gets
worse before it gets better. This is unusual and I can't think of a
reason that would be happening, but possibly something wasn't assembled
correctly.
if you have a stuck caliper things could be getting extremely hot. That
could explain the intermittent pedal to the floor if you are getting
things hot enough to boil brake fluid.
-jim
> >
> >Could the experts here give some insight into what the possible issues
> >could be? The advice here has always helped me in the past and look
> >forward to your opinion.
> >
> >Thanks and regards,
> >Mark
>
> Your problem sounds like the booster is not releasing which
> results in your brakes being partially applied. This
> explains both the low inconsistant pedal and the brake
> pulsation after driving a couple of minutes. You may be
> able to use your toe and lift the pedal to clear the problem
> until you apply the brake again. If the master cylinder was
> replaced, the mechanic may not have been able to effectively
> bleed the system to purge air from it.
>
> As an aside, it is usually best to replace both the booster
> and master cylinder if one fails and they are essentially
> the same age with significant miles on them. In you rcase
> at this point, I would have the booster replaced and the
> hydraulic system purge following the procedure in the
> manufacturer's service manual to be sure the ABS system is
> cleared. That year model may also require a scanner to
> correctly purge the ABS controller. You may want to have
> the brake pads checked for heat damage, glazing, cracking,
> disintegration, etc. to make sure the brakes are good to go.
> I had this happen on my CV a couple of years back right
> after a brake job. The pads were destroyed in less than 50
> miles after the problem began.
>
> Lugnut
Bill
particularly for the ABS?
"Mark" wrote in message
chuckcar
news:e52c66b9-90a0-4583...@w17g2000yqj.googlegroups.com:
> Hi,
>
> I have a lexus es300 with 128K miles. I had taken my car to the
> mechanic as I felt the brakes needed work. I had to press the brake
> pedal all the way down to stop the car. The mechanic suggested
> replacing the master cylinder which I did.
>
Why that as opposed to the pads or bleeding the air from the lines?
--
(setq (chuck nil) car(chuck) )
Tegger
c5a948...@s9g2000yqa.googlegroups.com:
> On Apr 5, 10:07 pm, Tegger <inv...@invalid.inv> wrote:
>> Mark <muf...@hotmail.com> wrote in news:e52c66b9-90a0-4583-a493-
>> 0671bdd93...@w17g2000yqj.googlegroups.com:
>>
>> > Hi,
>>
>> > I have a lexus es300 with 128K miles.
>>
>> What year?
>>
>> Does it have ABS?
>>
>
> Sorry, should have mentioned in my post. It is a '97 es300, and yes it
> does ABS.
Do you have any freeplay at the pedal?
Push the pedal with your fingetips, as lightly and gently as possible. You
should feel the tiniest bit of very easy movement before it hits something
solid and effort becomes much greater. You're looking for something like
this in the first 1/16" or 1/8" or so of pedal travel.
--
Tegger
Mark
mechanic and have it checked again. I'll also have him look into the
suggestions made here regarding proper bleeding, checking the vac
booster, the caliper and rotors. The pads and rotor were fine at the
time of replacing the master cylinder.
As a side note, I had the tires rotated and wheels balanced a couple
of times, but that didn't fix the problem. I have also been getting
the check engine light with code P0446 (Evaporative Emission Control
System Vent Control Circuit Malfunction). I didn't think it could be
related to the problems I am having, but wanted to mention it, just in
case there is a possibility of it being related.
Tegger: I will check for the freeplay in the brake pedal and report
back.
Thanks for your help,
Mark
Bill
> ...I have also been getting
> the check engine light with code P0446 (Evaporative Emission Control
> System Vent Control Circuit Malfunction).
>
One cause of evaporative system problems is constantly "topping off" the gas
tank when filling up. The charcoal canister which is used to filter fumes
from the gas tank can fill with gasoline if the tank is frequently "filled
to the brim".
If an attendant is filling your tank and you are paying with a credit card,
when the nozzle clicks, say "That is fine!" (They will want to fill it to an
even dollar amount for some reason? But not necessary since they are not
giving you change!) If paying cash, just go up to the next quarter, then you
will get quarters in change.
addre...@invalid.invalid
What's probably happened is that the rod which is connected to the
booster was not adjusted to the new master causing the brakes to stay
slightly applied. We live in hilly area here in BC Canada and run into a
problem called warped rotors. As the rotor gets overheated from over
braking, the two parallel surfaces of the brake rotor becomes warped.
These unparalleled surfaces cause the pads to move unevenly producing
the shake in the steering wheel and pulsation in brake pedal. The heated
rotors and pads cause a condition as brake fade. This codition requires
more pedal effort as brakes get hotter. The shaking is reduced ss the
rotors cool . The rod that pushes on the masters' piston is adjustable
for length to set free play. Too much length and the master will keep
pressure to the braking system. Setting proper lenghth will solve this
problem. The only other problem is to fix the warp rotors you need to
machine or replace the rotors back to two parallel surfaces.
Paul Hovnanian P.E.
lose vaccum and the brakes need a lot more pedal pressure. When the leak
occurs, the engine runs rough and shakes.
--
Paul Hovnanian mailto:Pa...@Hovnanian.com
------------------------------------------------------------------
Very funny, Scotty. Now beam down my pants!
Tegger
news:4BC3EEAA...@Hovnanian.com:
> Air leak (intermittent) between the booster and intake manifold. You
> lose vaccum and the brakes need a lot more pedal pressure. When the leak
> occurs, the engine runs rough and shakes.
>
If it were an air leak, the idle would be elevated.
Rough-idle and shaking were characteristics of non-feedback systems that
were unaware of loss of manifold vacuum. OP's Lexus has a feedback system.
--
Tegger
Paul Hovnanian P.E.
>
> "Paul Hovnanian P.E." <Pa...@Hovnanian.com> wrote in
> news:4BC3EEAA...@Hovnanian.com:
>
> > Air leak (intermittent) between the booster and intake manifold. You
> > lose vaccum and the brakes need a lot more pedal pressure. When the leak
> > occurs, the engine runs rough and shakes.
> >
>
> If it were an air leak, the idle would be elevated.
Not if the ECU compensates for the leak.
> Rough-idle and shaking were characteristics of non-feedback systems that
> were unaware of loss of manifold vacuum. OP's Lexus has a feedback system.
But a feedback system would compensate for the average error. If the
vacuum for the brake system is tapped off a part of te manifold nearer
one cylinder, it will throw that one's mixture off.
--
Paul Hovnanian mailto:Pa...@Hovnanian.com
------------------------------------------------------------------
"Arguing with anonymous strangers on the Internet is a sucker's game
because they almost always turn out to be, or to be indistinguishable
from
self-righteous sixteen-year-olds possessing infinite amounts of free
time."
- Neil Stephenson, _Cryptonomicon_
jim beam
> Tegger wrote:
>>
>> "Paul Hovnanian P.E."<Pa...@Hovnanian.com> wrote in
>> news:4BC3EEAA...@Hovnanian.com:
>>
>>> Air leak (intermittent) between the booster and intake manifold. You
>>> lose vaccum and the brakes need a lot more pedal pressure. When the leak
>>> occurs, the engine runs rough and shakes.
>>>
>>
>> If it were an air leak, the idle would be elevated.
>
> Not if the ECU compensates for the leak.
latitude to /decrease/ idle air is limited, and of this type,
insufficient. once there is a leak, the ecu increases fuel in ratio to
the air supply to maintain stoichiometry.
>
>> Rough-idle and shaking were characteristics of non-feedback systems that
>> were unaware of loss of manifold vacuum. OP's Lexus has a feedback system.
>
> But a feedback system would compensate for the average error. If the
> vacuum for the brake system is tapped off a part of te manifold nearer
> one cylinder, it will throw that one's mixture off.
and increase fuel delivery...
>
--
nomina rutrum rutrum
Tegger
> Tegger wrote:
>>
>> "Paul Hovnanian P.E." <Pa...@Hovnanian.com> wrote in
>> news:4BC3EEAA...@Hovnanian.com:
>>
>> > Air leak (intermittent) between the booster and intake manifold.
>> > You lose vaccum and the brakes need a lot more pedal pressure. When
>> > the leak occurs, the engine runs rough and shakes.
>> >
>>
>> If it were an air leak, the idle would be elevated.
>
> Not if the ECU compensates for the leak.
The ECM/PCM compensates by correcting the mixture AND the idle speed, or it
can compensate by correcting the mixture and ignoring the idle speed. OP's
Lexus probably does the former. Both our cars do the latter.
In any case, a feedback-system the ECM/PCM would compensate for an air leak
by shortening injector pulse width until fuel mixture and/or idle speed
were correct again. There would be no rough-running or shaking.
>
>> Rough-idle and shaking were characteristics of non-feedback systems
>> that were unaware of loss of manifold vacuum. OP's Lexus has a
>> feedback system.
>
> But a feedback system would compensate for the average error. If the
> vacuum for the brake system is tapped off a part of te manifold nearer
> one cylinder, it will throw that one's mixture off.
>
Possibly. But considering that vehicles with MAP sensors typically have
only one sensor for the entire intake manifold, I'd think pressure changes
at one cylinder would have minimal effect overall; certainly not enough to
induce roughness and shaking.
--
Tegger
jim
Tegger wrote:
> The ECM/PCM compensates by correcting the mixture AND the idle speed, or it
> can compensate by correcting the mixture and ignoring the idle speed. OP's
> Lexus probably does the former. Both our cars do the latter.
>
> In any case, a feedback-system the ECM/PCM would compensate for an air leak
> by shortening injector pulse width until fuel mixture and/or idle speed
> were correct again. There would be no rough-running or shaking.
The point was that a vacuum leak can cause a misfire if it affects one
cylinder more than the rest and a regular misfire isn't going to make an
engine idle smoothly. However, that doesn't have much to with the OP's
stated problem. He said:
"The car starts vibrating after driving for about
10 minutes on the highway. The vibration doesn't
start right away."
He also made it clear that the vibration is felt in brake pedal and
steering wheel. and then he said:
"After about 15 minutes of driving, the vibration goes
away and doesn't come back during the same ride."
If I read that correctly the vibration occurs between 10-15 minutes of
first getting up to highway speeds and at no other time. So no point
arguing about what might happen when the engine is idling.
He also said:
"The brake pedal sometimes works just by a little pressing,
and other times I need to press it all the way down."
If the booster isn't getting vacuum then the opposite would happen. The
pedal would not go down as far as normal and the braking power would be
reduced.
-jim
Tegger
news:Xns9D5A5682...@208.90.168.18:
>
> In any case, a feedback-system the ECM/PCM would compensate for an air
> leak by shortening injector pulse width until fuel mixture and/or idle
> speed were correct again.
Sorry, should have read "LENGTHEN pulse width" (to compensate for the
excess air).
--
Tegger
Mark
described earlier with the vibrating and brake master cylinder are
related? Sorry, some of this is way too technical for me. Thanks !
jim
Mark wrote:
No I don't think anyone suggested your DTC code and the brake/vibration
were related. The code means it failed one of the diagnostic tests that
are done on the system designed to keep raw fuel vapors from getting
into the environment.
-jim
Tegger
1c9b94...@5g2000yqj.googlegroups.com:
> Are you folks suggesting that the P0446 CEL and the problems I
> described earlier with the vibrating and brake master cylinder are
> related? Sorry, some of this is way too technical for me. Thanks !
No relation at all between P0446 and the master cylinder.
--
Tegger
Mark
Just an update... after bleeding the brake system again, the problem
with pedal to the floor has been resolved and now my braking is a lot
more consistent. But the vibration problem still exists. To summarize,
the steering wheel starts vibrating after about 10 minutes on the
highway. After another 15 minutes, the vibration goes away and then
the ride is smooth. During vibration, the brake pedal pulsates while
braking and increases the vibration in the steering. Do you have any
other suggestions? Would a road force balancing help?
Thanks a lot again for your help.
Nate Nagel
I would check your master cylinder pushrod adjustment. It may be
slightly applying the brakes causing the rotors to temporarily warp.
This isn't particularly good for your pads, rotors, calipers, etc.
nate
--
replace "roosters" with "cox" to reply.
http://members.cox.net/njnagel
jim beam
i made some suggestions and they're known to work for hondas. did you
try them on the lexus? it's a common issue with modern lightweight hubs.
--
nomina rutrum rutrum
Mark
Yes, I will definitely check that. That might also explain why the
brake is applied just by a slight touch of the brake pedal when the
vibration is occuring (and the brake pedal pulsates). When there is no
vibration, I have to push the brake pedal a little more.
Mark
I have a feeling it is the pushrod adjustment. While driving on the
highway today, the vibration in steering started occuring after about
10 minutes. I started feeling the pulsating pedal while braking. I put
my foot under the pedal and tried to lift it upwards while driving. As
soon as I did that, the vibration went away and there was no pulsation
while braking.
When I returned home, I felt the vibration coming back. I pulled over
(as I was on local roads), turned the engine off, put the car in
neutral and tried to push the car. The car wouldn't move. Then, I
lifted the brake pedal slightly with the foot and tried pushing the
car again in neutral. Now I was able to move the car.
That could explain that the vibration is occurring when the brake
pedal remains slightly pressed. Though I don't understand why this
would only occur after about 10 minutes of highway driving and go away
after 15 minutes.
If this is indeed the case, should I just take the car to the mechanic
and ask him to adjust the master cylinder pushrod?
Thanks again to everyone for your inputs.
Tegger
news:264bbbaa-8a6c-4218...@x40g2000yqd.googlegroups.com:
>
> I have a feeling it is the pushrod adjustment.
I posted this, on April 6th, one month ago:
"Do you have any freeplay at the pedal?
"Push the pedal with your fingertips, as lightly and gently as possible.
You should feel the tiniest bit of very easy movement before it hits
something solid and effort becomes much greater. You're looking for
something like this in the first 1/16" or 1/8" or so of pedal travel."
>
> If this is indeed the case, should I just take the car to the mechanic
> and ask him to adjust the master cylinder pushrod?
That's a bit difficult on most Toyotas; the booster needs to be removed
to adjust it. I suggest you (or your mechanic) try my month-old advice
first.
--
Tegger
Mark
I did follow your advise back then. I had checked and found there was
freeplay in the pedal. But I had checked when the car was cold. It
didn't occur to me to check it while the vibration was occuring.
Tegger
news:b0502625-5b9f-4adb...@k19g2000yqm.googlegroups.com:
> On May 5, 2:28�pm, Tegger <inva...@invalid.inv> wrote:
>> Mark <muff...@hotmail.com> wrote
>> innews:264bbbaa-8a6c-4218-9b3e-8c26cef64
> 5...@x40g2000yqd.googlegroups.com:
>>
>>
>>
>> > I have a feeling it is the pushrod adjustment.
>>
>> I posted this, on April 6th, one month ago:
>>
>> "Do you have any freeplay at the pedal?
>>
>> "Push the pedal with your fingertips, as lightly and gently as
>> possible. You should feel the tiniest bit of very easy movement
>> before it hits something solid and effort becomes much greater.
>> You're looking for something like this in the first 1/16" or 1/8" or
>> so of pedal travel."
>>
>>
>>
>> > If this is indeed the case, should I just take the car to the
>> > mechanic and ask him to adjust the master cylinder pushrod?
>>
>> That's a bit difficult on most Toyotas; the booster needs to be
>> removed to adjust it. I suggest you (or your mechanic) try my
>> month-old advice first.
>>
>>
>>
>
> I did follow your advise back then. I had checked and found there was
> freeplay in the pedal. But I had checked when the car was cold. It
> didn't occur to me to check it while the vibration was occuring.
>
You can only check it with the car stopped and you out of the driver's
seat.
If there truly is freeplay in the pedal, then the master cylinder is not
the problem.
--
Tegger
Mark
The couple of times I checked it, it was exactly as your described.
But that was before I took the car on a drive. Here is an example of
how I checked it: http://www.tegger.com/hondafaq/mastercylinderreplace/too-much-freeplay.jpg
(btw, is that your website?).
I found the freeplay to be there when I touched the pedal. There was a
very small freeplay, but it was there.
However, I get the vibration after about 10 minutes of driving on the
highway. When it happened today, I pulled over, turned the engine off,
put the car in neutral, got out of the car and pushed it. It wouldn't
move. Then I went back into the car, lifted the brake pedal with my
foot, then got out of the car and pushed it. Now I could easily push
the car. It meant, the brake pedal could have been stuck.
Next time the vibration occurs, I'll pull over, turn the engine off,
get out of the car and test the freeplay. If there is no freeplay at
that point, would that indicate a problem with pushrod?
Thanks again!
jim
Mark wrote:
There is no reason I can think of why the free play in the brake pedal would change after 10 minutes of driving.
The pedal may be binding or the return spring is broke or missing. But you should have noticed that the pedal
was not returning on its own when checking the free play. There isn't any reason I can think of that 10 minutes
of driving causes the brake pedal to become stuck down and then another 15 minutes it goes away.
-jim
Tegger
news:5b94431c-4c5d-4d5c...@q32g2000yqb.googlegroups.com:
> (btw, is that your website?).
Yes. But it's badly outdated, and I haven't got hours to spend updating it.
>
> I found the freeplay to be there when I touched the pedal. There was a
> very small freeplay, but it was there.
>
> However, I get the vibration after about 10 minutes of driving on the
> highway. When it happened today, I pulled over, turned the engine off,
> put the car in neutral, got out of the car and pushed it. It wouldn't
> move. Then I went back into the car, lifted the brake pedal with my
> foot, then got out of the car and pushed it. Now I could easily push
> the car. It meant, the brake pedal could have been stuck.
>
> Next time the vibration occurs, I'll pull over, turn the engine off,
> get out of the car and test the freeplay. If there is no freeplay at
> that point, would that indicate a problem with pushrod?
Probably not. But this new information is very interesting, indeed.
If you can pull the pedal up so the brakes release, then master-cylinder
ajustment is not the issue. At the moment, this sounds more like a problem
with pedal-height misadjustment, or with something sticking at the pedal,
or inside the master cylinder itself. Or possibly the booster applying
itself.
If it were me, I think I'd start by disconnecting and plugging the vacuum
line from the booster, to see if the problem goes away. Of course, this
would be done in a safe place, where it didn't matter if the brakes took
superhuman effort to apply...
Basically, troubleshooting here will require separating the various systems
and testing them separately, to determine which one is causing this
stickiness.
Is this an aftermarket master cylinder?
--
Tegger
Mark
I took the car on another test drive to check the free play of the
brake pedal before and after vibration. Before driving, I found the
free play to be there. Then after driving for ~10 minutes on the
highway, once the vibration and pulsating brake pedal kicked in, I
pulled over. Immediately, I checked the brake pedal and the free play
was as before, there was no change. But putting the car on neutral
with engine off made it difficult to push the car. Then I got in the
car, using my toe lifted the brake pedal a couple of times and now I
could push the car easily in neutral. Then, once I got on the highway
and started driving, the vibration in the steering was gone. I have
been able to replicate this behavior twice today. If the problem is
not with the master cylinder pushrod and the brake pedal free play,
then is the brake pedal simply getting stuck temporarily?
Mark
> Is this an aftermarket master cylinder?
> --
> Tegger
Yes, this is an aftermarket master cylinder.
jim
I guess the rod from the brake booster to the master cylinder doesn't
have clearance. I suspect you will find if you check that the brakes are
dragging whenever the car is cold. To test that when you first start the
car apply the brakes nd then release them and check to see if the car
rolls freely. If they are sticking pulling up on the pedal will probably
release them as you have discovered.
To adjust the push rod that connects booster to master cylinder you
will need to unbolt the master cylinder from the booster. There may be
gasket between the master cylinder and booster that wasn't installed or
the new MC was just a little different than the original.
-jim
jim beam
that doesn't explain why the pedal sticks in the "down" position. i'm
with tegger - i've seen pistons stuck in the cylinder of poorly machined
cheapo aftermarket brake masters.
--
nomina rutrum rutrum
jim
jim beam wrote:
>
> that doesn't explain why the pedal sticks in the "down" position. i'm
> with tegger - i've seen pistons stuck in the cylinder of poorly machined
> cheapo aftermarket brake masters.
You have to be exceedingly ignorant and stupid to believe that. When
you pull up on the brake pedal you are not pulling the master cylinder
piston. The MC piston returns on its own - it is never pulled by the
push rod. It cannot be pulled by the push rod. That is physically
impossible. If the master piston was stuck and couldn't move as you
believe it is then no amount of pulling on the brake pedal is going to
do anything about that.
You believe in stupid fairy tale superstition about after-market parts
not based on fact.
There is nothing in the narrative that suggests the master cylinder is
misbehaving. Something is preventing the master cylinder from returning
back to the position where the brake fluid pressure is released. And
that something is the push rod between the booster and master
cylinder. If the piston is not returning it is because the push rod is
not retracting far enough to allow it to return. When he pulls on the
brake pedal he removes the something that prevents the piston and push
rod to return. And when he does that then the MC behaves just like an
OEM MC would.
The most likely cause of this problem is the push rod is not adjusted
correctly. It's possible the adjustment is off because the spacer
(gasket) between the MC and booster is missing. If that isn't the cause
then it is inside the booster that something is sticking and not
allowing the push rod to retract far enough.
-jim
jim beam
why don't you read before you rant? nothing i've said is inconsistent.
yes, stuck pistons stay stuck and the rod is not attached, but that's
not the end of the story.
and evidently unlike you, i've actually seen poor quality aftermarket
master cylinders and experienced problems with stuck pistons. adjusting
a push rod doesn't address this and is such a commonly mis-suggested
remedy, it's just ridiculous. push rods should hardly ever be adjusted
once out of factory. if a replacement master is out of spec, it should
be returned. if the pedal pivot bearings have worn, they should be
replaced. adjusting a push rod is NOT the solution to either problem
and they are the only causes of the thing going out of spec.
as for diagnosis, maybe i should be more specific for those with reading
challenges - when i say "i'm with tegger on this", i agree with his
statement "I think I'd start by disconnecting and plugging the vacuum
line from the booster", etc. now you can go back to your tv and ice cream.
--
nomina rutrum rutrum
jim
jim beam wrote:
I don't doubt you have had all kinds bad auto repair experiences which you have
blamed on various hobgoblins and demons.
> push rods should hardly ever be adjusted
> once out of factory. if a replacement master is out of spec, it should
> be returned. if the pedal pivot bearings have worn, they should be
> replaced. adjusting a push rod is NOT the solution to either problem
> and they are the only causes of the thing going out of spec.
BS from a babbling buffoon. There is nothing that would suggest the MC is out of
spec.
And Lexus would also say you are completely full of shit. According to Lexus
service instructions the push rod coming out of the booster should always be
adjusted whenever the master cylinder is replaced. Lexus even sells special tools
for measuring the clearance.
Maybe you should try to explain to Lexus how ridiculous their "commonly
mis-suggested remedy" is.
>
>
> as for diagnosis, maybe i should be more specific for those with reading
> challenges - when i say "i'm with tegger on this", i agree with his
> statement "I think I'd start by disconnecting and plugging the vacuum
> line from the booster", etc.
HA HA HA what buffoon. Here is what you wrote:
[Quote]
i'm with tegger - i've seen pistons stuck in
the cylinder of poorly machined
cheapo aftermarket brake masters.
[End Quote]
This piston is not stuck in the master cylinder. If it were lifting up on the
pedal would do nothing at all to release the brakes.
jim beam
inability to discern fact from friction? so hard to decide!!!
--
nomina rutrum rutrum
jim
jim beam wrote:
>
> inability to discern fact from friction? so hard to decide!!!
>
Yup that is what it boils down to. For instance, when someone says they
only use OEM parts and also claims to have vast experience with poor
quality after-market parts it does make one wonder if those statements
are fact or fiction.
-jim
jim beam
don't put put bullshit twisted illogical words in my mouth. well, not
unless you can delude yourself that it doesn't make you look stupid, in
which case, feel free to keep ranting.
--
nomina rutrum rutrum