mwatt Posted January 17, 2008 Share Posted January 17, 2008 on our '98 Legacy Outback. We've owned the car since new and I've replaced the master cylinder twice. Additionally, Subaru replaced it once because of the recall involving the brake pedal possibly sinking to the floor in cold temps. Well, it's happening again---in warm or cold weather. The pedal sinks down too low on first application but feels normal again after it's pumped once. It isn't a booster problem because pedal effort is normal.The brake fluid level never changes---we're not loosing fluid anywhere. I've thoroughly inspected pads, lines and hoses on this car and there's nothing obvious wrong, although the rear pads are getting a little thin---but that's not gonna' cause a low pedal that "pumps up" and feels normal again.........has anyone else had to deal with this issue? One thing I remember is that each time I've replaced the master cylinder I've refilled and bled the system with Prestone DOT3 synthetic brake fluid.....but it's labeled for use in all vehicles using standard DOT3 fluid...... Quote Link to comment Share on other sites More sharing options...
porcupine73 Posted January 18, 2008 Share Posted January 18, 2008 Have you done the booster test? You know like hold brake pedal down, shut off engine, shouldn't drop pedal for one minute, then pump three or four times, pedal travel should decrease each time, then with foot on pedal restart vehicle and pedal should drop slightly? AFIAK brake fluid is all 'synthetic'. There aren't any dot3/dot4 'dino' brake fluids. Quote Link to comment Share on other sites More sharing options...
Bserk Posted January 18, 2008 Share Posted January 18, 2008 I'll take a shot at this since no one has posted yet.. I notice you are in Maryland, so this may not be as applicable as to cars here in the 'salt belt'. The biggest cause of a low brake pedal here is either the caliper slider pins, or the brake pads themselves becoming 'frozen' from rust. The pads could visually look fine, but if they cant move when the brakes are applied, or the caliper slider pins cant move, it will definitely cause a low pedal. It was one of the first things I went through with my car (96 OB) I was very familiar with the problem because it happens all the time here with the Nissans I deal with all the time. And its worse with a 4 wheel disc system, since all 4 brakes can have the problem. Any chance of corrosion on the brakes then I would definitely start there. Quote Link to comment Share on other sites More sharing options...
porcupine73 Posted January 18, 2008 Share Posted January 18, 2008 Maybe you have air trapped in the ABS hydraulic unit? Maybe you should bleed the brakes while putting the abs unit through sequence control. Quote Link to comment Share on other sites More sharing options...
mwatt Posted January 18, 2008 Author Share Posted January 18, 2008 Maybe you have air trapped in the ABS hydraulic unit? Maybe you should bleed the brakes while putting the abs unit through sequence control. Well, no---I haven't done the booster test yet, but I still don't think it's a booster issue because the pedal is easy to press, it just goes down too far on the first application. I think I'm correct (and believe me, I'm often wrong---just ask my wife) when I assume that a booster problem would result in the brake pedal being too difficult to depress. But what is "putting the abs unit through sequence control". I used to work at a dealership for years, and I thought I knew about brake bleeding procedures (including bench bleeding a new master cylinder) but that's a term I'm not familiar with...... Quote Link to comment Share on other sites More sharing options...
nipper Posted January 18, 2008 Share Posted January 18, 2008 Brake booster test must be done as a master cylinder and booster can both feel the same, and can both come and go. Pump the barke pedal 10 times with the car off. Put fott on brake pedal. Start car, pedal should move to the floor. Also do this test first thing in the morning. If it passes this test, clean or replace the check valve for the brake booster. Its not the ABS unless the ABS is leaking. ABS is a flow through design, so it wont affect it if its not operating. How old is the brake fluid. nipper Quote Link to comment Share on other sites More sharing options...
mwatt Posted January 18, 2008 Author Share Posted January 18, 2008 I'll take a shot at this since no one has posted yet.. I notice you are in Maryland, so this may not be as applicable as to cars here in the 'salt belt'. The biggest cause of a low brake pedal here is either the caliper slider pins, or the brake pads themselves becoming 'frozen' from rust. The pads could visually look fine, but if they cant move when the brakes are applied, or the caliper slider pins cant move, it will definitely cause a low pedal. It was one of the first things I went through with my car (96 OB) I was very familiar with the problem because it happens all the time here with the Nissans I deal with all the time. And its worse with a 4 wheel disc system, since all 4 brakes can have the problem. Any chance of corrosion on the brakes then I would definitely start there. Besides porcupine73's suggestion, this is a good one, too. While they don't use much road salt here, they do use some.... It's easy enough to remove the lower caliper bolts and tilt the calipers upward for pad inspection. So this weekend I'll check the sliders and pistons to make sure they're not seized. Quote Link to comment Share on other sites More sharing options...
nipper Posted January 18, 2008 Share Posted January 18, 2008 Besides porcupine73's suggestion, this is a good one, too. While they don't use much road salt here, they do use some.... It's easy enough to remove the lower caliper bolts and tilt the calipers upward for pad inspection. So this weekend I'll check the sliders and pistons to make sure they're not seized. Yup that would do it too. nipper Quote Link to comment Share on other sites More sharing options...
mwatt Posted January 18, 2008 Author Share Posted January 18, 2008 If you pass the booster test, clean the check valve in the va line to the brake booster or replace it. nipper OK......buuuuuuutttttt......I still don't think the booster or vaccum supply to the booster is the issue here. Remember---the pedal remains easy to press----it just goes down too low. OK---OK I'm sitting here thinking.....I should not be simply dismissing any of this advice. I'll do the booster test the porcupine suggested.....and I'll look at the booster check valve...... Quote Link to comment Share on other sites More sharing options...
nipper Posted January 18, 2008 Share Posted January 18, 2008 OK......buuuuuuutttttt......I still don't think the booster or vaccum supply to the booster is the issue here. Remember---the pedal remains easy to press----it just goes down too low. OK---OK I'm sitting here thinking.....I should not be simply dismissing any of this advice. I'll do the booster test the porcupine suggested.....and I'll look at the booster check valve...... Its not a matter of it cant be this because, its a matter of ruling things out. Best time to check all this is first time the car is driven, otherwise you may see them at all. nipper Quote Link to comment Share on other sites More sharing options...
mwatt Posted January 18, 2008 Author Share Posted January 18, 2008 Brake booster test must be done as a master cylinder and booster can both feel the same, and can both come and go. Pump the barke pedal 10 times with the car off. Put fott on brake pedal. Start car, pedal should move to the floor. Also do this test first thing in the morning. If it passes this test, clean or replace the check valve for the brake booster. Its not the ABS unless the ABS is leaking. ABS is a flow through design, so it wont affect it if its not operating. How old is the brake fluid. nipper I'm beyond anal about maintenance on our Subarus. Brake fluid is flushed every two years since the car was new. Quote Link to comment Share on other sites More sharing options...
mwatt Posted January 18, 2008 Author Share Posted January 18, 2008 Its not a matter of it cant be this because, its a matter of ruling things out. Best time to check all this is first time the car is driven, otherwise you may see them at all. nipper Thanks everyone for advice---will keep you posted. Quote Link to comment Share on other sites More sharing options...
dkingma Posted May 10, 2009 Share Posted May 10, 2009 Hi. I just joined this forum. 2000 Outback with the low pedal situation. Drives me crazy. I'm also anal about my Subi but the low brake pedal thing drives me nuts. Dealer says it's normal. Car does stop but the pedal it's so low! It will pump up a little so it "feels" better. Read all the post but no real fix. Quote Link to comment Share on other sites More sharing options...
nipper Posted May 10, 2009 Share Posted May 10, 2009 Wlecome. How many miles? When was the last time the breaks were done? When was the last time the brake fluid was changed? nipper Quote Link to comment Share on other sites More sharing options...
tcspeer Posted May 10, 2009 Share Posted May 10, 2009 I had this problem also on a 98 Postal Legacy Wagon. We get to do lots of brake work on these things and I do most of the brake work myself. However I could not figure this one out, I also replaced the master cyclinder. So I took it to Midas, as the owner is a freind of mine, He found the problem on this one, it was a bad front caliper. They have brake hose pinchers which they pinch the brake line before the caliper and once this line was pinched the pedal was able to be restored, you can buy a set of brake line pinchers from Snap On, they are one of the few things they sell that dont cost much. This caliper I guess was just letting a little air leak by as there was no brake fluild leak what ever. This may or may not be your problem but it is just a suggestion to check if you give up on all else. Quote Link to comment Share on other sites More sharing options...
nipper Posted May 10, 2009 Share Posted May 10, 2009 I had this problem also on a 98 Postal Legacy Wagon. We get to do lots of brake work on these things and I do most of the brake work myself. However I could not figure this one out, I also replaced the master cyclinder. So I took it to Midas, as the owner is a freind of mine, He found the problem on this one, it was a bad front caliper. They have brake hose pinchers which they pinch the brake line before the caliper and once this line was pinched the pedal was able to be restored, you can buy a set of brake line pinchers from Snap On, they are one of the few things they sell that dont cost much. This caliper I guess was just letting a little air leak by as there was no brake fluild leak what ever. This may or may not be your problem but it is just a suggestion to check if you give up on all else. i had a frozen rear claiper giving a wierd pedal, thats why i was asking when was the last time he had the brakes done. Quote Link to comment Share on other sites More sharing options...
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