Problems after replacing master cylinder
in [Technical]
|
From: Mark on 4 May 2010 23:22 On May 4, 9:45 pm, Nate Nagel <njna...(a)roosters.net> wrote: > On 05/04/2010 07:30 PM, Mark wrote: > > > > > On Apr 6, 10:31 am, jim<"sjedgingN0Sp"@m(a)mwt,net> wrote: > >> lugnut wrote: > > >>> On Mon, 5 Apr 2010 18:33:16 -0700 (PDT), Mark > >>> <muff...(a)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 > > > 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. > > 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 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.
From: Mark on 5 May 2010 14:22 On May 4, 11:22 pm, Mark <muff...(a)hotmail.com> wrote: > On May 4, 9:45 pm, Nate Nagel <njna...(a)roosters.net> wrote: > > > > 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 > > 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. 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.
From: Tegger on 5 May 2010 14:28 Mark <muffi74(a)hotmail.com> wrote in news:264bbbaa-8a6c-4218-9b3e-8c26cef64527(a)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
From: Mark on 5 May 2010 16:15 On May 5, 2:28 pm, Tegger <inva...(a)invalid.inv> wrote: > Mark <muff...(a)hotmail.com> wrote innews:264bbbaa-8a6c-4218-9b3e-8c26cef64527(a)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 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.
From: Tegger on 5 May 2010 16:50
Mark <muffi74(a)hotmail.com> wrote in news:b0502625-5b9f-4adb-84a0-3f82067f4054(a)k19g2000yqm.googlegroups.com: > On May 5, 2:28�pm, Tegger <inva...(a)invalid.inv> wrote: >> Mark <muff...(a)hotmail.com> wrote >> innews:264bbbaa-8a6c-4218-9b3e-8c26cef64 > 527(a)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 |