Problems after replacing master cylinder
in [Technical]
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From: Mark on 5 May 2010 16:58 On May 5, 4:50 pm, Tegger <inva...(a)invalid.inv> wrote: > Mark <muff...(a)hotmail.com> wrote innews: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 > > 5...(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 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!
From: jim on 5 May 2010 17:42 Mark wrote: > On May 5, 4:50 pm, Tegger <inva...(a)invalid.inv> wrote: > > Mark <muff...(a)hotmail.com> wrote innews: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 > > > 5...(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 > > 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? 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
From: Tegger on 5 May 2010 17:53 Mark <muffi74(a)hotmail.com> wrote in news:5b94431c-4c5d-4d5c-9176-a451bd04b037(a)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
From: Mark on 5 May 2010 23:11 Tegger, Jim, 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?
From: Mark on 5 May 2010 23:12
On May 5, 5:53 pm, Tegger <inva...(a)invalid.inv> wrote: > Is this an aftermarket master cylinder? > -- > Tegger Yes, this is an aftermarket master cylinder. |