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390 messages, Last post on Oct 31, 2009 at 11:59 AM
You are in the Maintenance & Repair Forum. Your Host is mr_shiftright
This topic will hopefully allow the more knowledgable of our community members share what they know with those seeking a good explanation for "how things work" in a car; or, this is a good place for equally knowledgable people to discuss the finer points of a technology.
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Replying to: sk2b1 (May 20, 2009 11:42 am) |
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Replying to: sk2b1 (May 20, 2009 11:42 am) |
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Our '97 Montero Sport just started having a brake issue. When you first get into it, the pedal is fine and everything works great. After a few miles, the brakes start dragging and it gets increasingly worse until you just pull over. The first time it happened to our son and he was only about 5-8 miles from our house. He was getting a couple of tanks of propane filled. By the time he was done paying, it was okay again. He returned home and told me about it. I took it out for just a bout 5 or so miles and saw no symptoms. The next evening, we took it out for another drive Round trip had to be about 30 miles, but we did have a 10 minute stop in between. We did not really notice the dragging, but we did notice the pedal got much higher (very little play). It could have been dragging a little, but I had my wife driving because it is her car and thought she would notice the differences better. The only thing she noticed was the decresed play in the pedal. My son was again driving it to school the next morning and he only made it about 7 miles before they started dragging really bad. I went and took him to schood. We were going to have it towed, but by the time we got back it was again normal so we drove it home. Since I was unsure of which wheels may have issues, I went out that evening and I jacked up all 4 corners and they turned freely. Tonight I drove the car around here for maybe 5 or so miles. I did some start and stops and some normal braking, but I did not drag the brakes on anything out of normal. I noticed the pedal play getting shorter so I headed towards the house. By the time I got home, it was dragging pretty bad. I then jacked up all 4 corners and every wheel was locked up if you were just trying to spin by hand. Since it is pretty much all 4 wheels reacting the same, I am thinking the master cylinder or the booster. Anyone experienced this before. I wouldn't think it would be the rubber lines since it is affecting all 4 wheels equally, but I am guessing there could also be a valve that is getting clogged and acting like a check valve.
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Replying to: kbc6313 (Jun 03, 2009 8:51 pm) |
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Replying to: kbc6313 (Jun 03, 2009 8:51 pm) Moisture and crude gets into the brake system, and collects down in the calipers, behind the pistons. It can corrode the inside of the caliper. The problem usually surfaces after a brake pad change, when the pistons are pressed back into the caliper (required to make room for the thicker brake pads). Pressing the piston back, forces the piston back onto the area of crude and corrosion, and the piston begins to stick and not 'float freely' as required. Putting on the brakes puts tremendous hydraulic pressure on the piston, and it is able to force the piston out okay. However when you take your foot off of the pedal, the piston isn't able to float back and the pad stays engaged with the rotor. Your rotors start to get very hot (and can warp), you can usually smell the overheating, and the brakes stay engaged. Pads wear out quickly. I usually replace the calipers with every 2nd set brake pad change. They're cheap enough, easy to do. Flush the fluid with every change. How old are those calipers? and how often have you flushed the brake fluid? If this was my vehicle, I'd do a complete brake job replacing all calipers, pads, fluid, and rotors.
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Replying to: kiawah (Jun 04, 2009 1:32 am) |
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Replying to: kbc6313 (Jun 04, 2009 4:10 pm) You haven't indicated that you've done previous maintenance of flushing hydraulics or replacing calipers, so for a vehicle as old as that is.....those calipers would be my first suspect. Compare the color of the hydraulic fluid with new clear fluid. Calipers are a simple change, and you need to start with the basics Good luck with whatever you decide to do. |
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Replying to: kbc6313 (Jun 04, 2009 4:10 pm) Like the ABS system is completely screwed up. Is there a Check Engine Light turned on? If so, have you checked the code? Or, is the Brake Light turned on, or some warning regarding the brake system? On some cars, the ABS braking system is a separate 'code setting' system from the main Check Engine Light, and sometimes even has a separate plug to access the codes.
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Replying to: bolivar (Jun 04, 2009 10:47 pm)
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Replying to: kbc6313 (Jun 05, 2009 5:34 pm) Are you sure all 4 wheels are dragging or locking up? A corroded caliper piston (I had one of those) may not allow the brake pad to retract from the disc, but that would keep the brakes on 2 of the 4 wheels pressurized. Same thing for a caliper slide or corroded surface the caliper slides on. Yes, you should flush the system. But if something has already been corroded, flushing will probably not fix the problem. |
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