I have a 91 Corolla sedan. The brake pedal was very soft and it wasn't stopping very well at all. I replaced the rear brake shoes as I was told they were bad. Didn't fix the problem. Took it to a shop for a "free brake check" and they told me they'd have to charge me $20 to bleed the brakes to 'see' if that would fix it so I said fine. They said that didn't fix it and it'll need a new master cyl and quoted me $300. I said I'd check back.
I went down the road to another shop that I trust and have used before in the past. They quoted me $200 for the master cyl. So I said go ahead and do that. So for a few days after, it was great! Plenty firm and stopping well. Then it began only occassionally working right. Then t got worse again, as if it was never fixed I took it back and they said I'd have to leave it there for a few days for them to drive and observe it since I couldn't tell them how to simulate the problem as seemed totally random. So I finally left it there with them for about 3 days and they claimed the pedal was never soft for them.
So I came and got it, and it was semi-firm but quickly went soft again.
It's not losing any fluid and the brake booster seems to be working okay (if I go by the "test" method of turning off the car and pumping the brake pedal a few times and it firms up very hard so you can't even press it down anymore). When i start the car, it goes down. If I'm in park and idling, if I pump it several times, it firms up but the next time i press the brake again it is soft again.
The shop that did the master cyl said they don't know what the problem could be and said it wasn't soft at all for them.
I have an interesting question in regards to bleeding the brakes on this car though. Due to the brake booster... do you not need the key turned in order to bleed the brakes properly? Otherwise the pedal would get firm after only a few pumps.. or is that only when the bleeder valves are closed? The Haynes manual says nothing about turning the key. Was this just an oversight or does it bleed okay without the key turned? Or maybe it has a massive air bubble that can only be gotten out with the key turned so the brake booster doesn't firm up the pedal?
I am at my wits end with this. I have no desire to pay another $200 to replace a brake booster that may be working just fine.
The only other cause I can think of is vacuum. The car does idle pretty rough and probably isn't running as well as it should. It probably needs a tune up. I did replace the plugs and wires a few months ago but that's all. The air filter looks fairly clean as well.
Not sure that it matters with this issue but I'll mention it anyway: It has a minor oil leak that appears to be by the distributor. I keep my eye on it and top it off as needed. I change the oil every 6 months or every 3,000 miles (as per the manual).
I guess I will also mention that the A/C seems like it puts more strain on the engine than maybe is normal but that may be a tune-up issue.
To bleed brakes, if done manually, the key does need to be on because you need the brake pedal. But no key is needed when bleeding the brakes using a vacuum pump.
It could be a check valve on one of the related vacuum lines?
I would check the rear brake cylinders. The seals could be shot if they are originals. Also the rubber brake lines. they may have a weak spot and balloon under pressure.
I would check the rear brake cylinders. The seals could be shot if they are originals. Also the rubber brake lines. they may have a weak spot and balloon under pressure.
Well, the shop who did the free brake check and the shop who did the master cyl said they didn't see any leaks so I don't think seals would be an issue. The rubber brake lines could be an issue they overlooked however.
I may take it to a more traditional garage I know of where the owners actually do the work. He's the type to allow/suggest you go buy the parts and bring them with you so he can just charge you labor so it will be cheaper for you. If he spots something wrong that the other two shops didn't, I may just let him repair it if it's the rubber brake lines or something else that doesn't cost too much.
a new master can be bad, it does happen. new part does not mean good part. it sure does sound like an internally leaking master cylinder to me.
Yeah, that's why I took it back to that same shop. They claim it was working just fine for them though. According to them it's operating just fine so why should they take it off and put on another one?
I also have never heard of any key needing to be turned for bleeding brakes. The brake booster has no electrical or mechanical connection to the key so I don't see why it would be needed.
The only connection the booster has to the key is this: Key turns on engine, engine runs and makes vacuum, vacuum powers booster. And since you don't need the engine on to bleed brakes, you don't need the key.
When you step on the pedal and hold it (engine on or off) does the pedal sink or stay firm? If it stays firm, then there shouldn't be a leak internal or external. Perhaps try bleeding it again.
I also have never heard of any key needing to be turned for bleeding brakes. The brake booster has no electrical or mechanical connection to the key so I don't see why it would be needed.
The only connection the booster has to the key is this: Key turns on engine, engine runs and makes vacuum, vacuum powers booster. And since you don't need the engine on to bleed brakes, you don't need the key.
When you step on the pedal and hold it (engine on or off) does the pedal sink or stay firm? If it stays firm, then there shouldn't be a leak internal or external. Perhaps try bleeding it again.
If the key is off and you press the brake pedal several times, it firms up very tight and stays that way until you start the engine and then it goes back down considerably.
The first press down with the engine off since I got home done just now after reading your post, it felt like it went down as far as it could. After pumping the brake with the engine off, it's now firm as can be. I guess I misunderstood how the booster worked.
But anyhow, I'll have to get a neighbor to sit in the car and pump the brake while I check the brake hoses since I can't be in two places at once.
Basically, where I stand thus far is I paid to have the brakes bled, did no good. Paid to have the master cyl replaced which means they had to replace the fluid and bleed the brakes. Worked okay for a week or so then resumed acting like crap. The shop who did the master cyl insists they found nothing wrong with it anywhere so it looks like I'm not going to get anything out of them without paying more money and they said they don't know if doing anything else to it will fix it or not. I could throw another $200 at it for a new brake booster and they can't guarantee that it would solve the problem.
If the key is off and you press the brake pedal several times, it firms up very tight and stays that way until you start the engine and then it goes back down considerably.
The first press down with the engine off since I got home done just now after reading your post, it felt like it went down as far as it could. After pumping the brake with the engine off, it's now firm as can be. I guess I misunderstood how the booster worked.
But anyhow, I'll have to get a neighbor to sit in the car and pump the brake while I check the brake hoses since I can't be in two places at once.
Basically, where I stand thus far is I paid to have the brakes bled, did no good. Paid to have the master cyl replaced which means they had to replace the fluid and bleed the brakes. Worked okay for a week or so then resumed acting like crap. The shop who did the master cyl insists they found nothing wrong with it anywhere so it looks like I'm not going to get anything out of them without paying more money and they said they don't know if doing anything else to it will fix it or not. I could throw another $200 at it for a new brake booster and they can't guarantee that it would solve the problem.
Well everything you've mentioned thus far sounds like it's pointing to a bad brake booster. The only purpose it has is to assist with applying pressure on your brakes when you push the pedal (i.e. power brakes). It does this via vacuum from the engine. At worst go get one from a wrecked car and see if it fixes the issue, then atleast you know it's the problem and can replace it accordingly.
Yeah, I have thought about trying to just put a new or used booster on myself. The hardest part will be bleeding the brakes myself. I did it once on my motorcycle and had a hell of a time doing so.. and that was only one brake to bleed as the rear one is mechanical. Plus I could see and reach everything by myself. I used a cheap small one-man brake bleeder from Harbor Freight but it finally did the trick. But on the car, I'll have *four* to bleed. ugh..
When you replaced the rear shoes did you adjust the star wheels so that there was proper clearance between shoes and drums? Also the rear wheel cylinders can have internal leakage(not visible leakage) that would cause low pedal and poor braking. Wouldn't be surprised if they are the originals. Did you replace the front pads at same time? if the master cylinder was a poor quality rebuild it could the cause .
When you replaced the rear shoes did you adjust the star wheels so that there was proper clearance between shoes and drums? Also the rear wheel cylinders can have internal leakage(not visible leakage) that would cause low pedal and poor braking. Wouldn't be surprised if they are the originals. Did you replace the front pads at same time? if the master cylinder was a poor quality rebuild it could the cause .
Yeah, I had to adjusted the star wheels a few times. First they were too tight. About never got the hub back off. Trying to adjust them from the access hole is about impossible. Then I had it too loose where the parking brake didn't do a thing. I finally got it in between where the parking brake would keep the car from moving when in placed in drive.
I didn't do the front pads. I know you're supposed to but I was doing what I could on my budget. I tried doing the go in reverse and press the brake hard and that didn't seem to do much if anything. When I had the master cyl done, I mentioned the star wheels to the shop so they could adjust them if needed while they were working on bleeding it anyway.
It could very well be an internal leak I suppose. It kind of ticked me off that the shop acted like they didn't know squat about brakes or possible causes for the symptoms. Rather than suggesting possible causes they just said they didn't know. They claimed it never does it for them so they don't know what the cause could be for brakes that would get firm and soft off and on.
I'm actually only the second owner of the car. My mom bought it new in 1991. But it's been an awful lot of years and there's no way she'll remember if she ever had the rear brake master cyl's replaced. The right front one got replaced for sure in Dec '94 when someone smashed into the front right side at the wheel, nearly totaling the car.
One reason I only did the rear brakes is when she still had the car, she had only the front brake pads done due to her budget at sometime in 2008.
Yeah, I have thought about trying to just put a new or used booster on myself. The hardest part will be bleeding the brakes myself. I did it once on my motorcycle and had a hell of a time doing so.. and that was only one brake to bleed as the rear one is mechanical. Plus I could see and reach everything by myself. I used a cheap small one-man brake bleeder from Harbor Freight but it finally did the trick. But on the car, I'll have *four* to bleed. ugh..
Well if you're careful you don't need to remove the lines from the master cylinder when you separate it from the booster so there would be no need to bleed the brakes. I've done this before but it can be tricky if you're not careful.
*The rear brakes should be adjusted to the point where they just barely touch the drum (rotate the drum to get only the highest spots)
*To adjust the rear brakes while going backward, pull up the hand brake several times (20-30), don't press the pedal.
*Go to the guy that lets you buy your own parts. He sounds like someone you can trust. Don't go back to the other shops again.
*The key (or engine) don't need to be on to bleed the brakes.
*I believe if the booster goes bad, the pedal should get harder, not softer.
I say check the adjustment on the rears again, if that is good, pull the dust covers on the rear wheel cylinders and see if it is wet in thare. If any one is wet under the dust cover, that would indicate a leak, so you should replace those.
If one is leaking, I would suggest changing both.
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'87 Corolla, AE82 FX-16, 4A-GZE swap (autocrosser)
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