I have a 1997 Saturn SL2 with ABS Brakes. I have replaced the driver's side caliper and brake pads on both front sides. I have also bled both brakes in the front. When I push on the brake pedal, the pedal goes all the way to the floor before coming to a VERY slow stop. When I pump the brakes and hold them, I have no pressure and they still go to the floor. What can this problem be?
Air in the system or a defective master cylinder. Saturn, like almost all front wheel drive cars, uses a diagonal split brake hydraulic system. The left front and right rear brake are on one circuit, right front and left rear are on another. Bleed sequence is RR, LF, LR, RF. Should have a good spurt of fluid when each bleeder is opened with the brake pedal depressed. If not, the master cylinder is probably pooched. Often, a previously working master cylinder can become damaged when bleeding brakes by overstroking the pistons into an area of the bore which may have corrosion buildup, tearing the cup seals on the pistons.
Of course the warranty is over on the front rotors, and I cannot take the wheel pulse and shudder any longer. The rotors are so warped. I bought new replacements, drilled & grooved. I have the true Jeep manual for the 2004 model and removal looks straight forward. I have, in recent past, changed pads on a 1994 JGC, a 97 Honda, etc., but never have I removed the rotors. Am I in for more than I think here, of is this an okay deal for my level of DIY'er? Anyone, not an auto mech done it? Thanks all.
I felt prepared and qualified to do the front rotors and brake pads exchange with the help of my Haynes Manual #50025, but opted to have a pro do it. I handed him my new rotors and pads and paid $75.00 for his work. I would have spent half a day on the job, with all the messing around that would have been required to do it at home. Yeah, I got lazy, but the results on my daughter's 2004 Laredo are very pleasing.
I know my car is different ( 96 Bonneville) but my car went though the same thing. Had all my brake lines replaced from ABS motor to the wheels and my fuel line also replaced due to leaks. All for $253.74 including taxes from my local garage. I double checked his work as I couldn't believe he did it for so cheap, but all the work was done and done well. Even if they have to drop your tank most garages will only charge $100.00 to do so. Get a second opinion.
Hello, I'm looking to redo my brakes on my Galant, and need to know how to get a detailed instruction manual. I've been reading through some of the threads, and it looks like you get what you pay for, so I'm hoping to go with the Raybestos QS style. Is there anything I need to know before attempting this as a first timer?
i have a 1990 chev astro van master went out replaced blew a brake line so i did all the brake bleed them adjusted rears but my brakes light and abs light stays on all the time have good pedel help
Check first with your area big chain store auto parts places. They should be able to tell you if a Haynes or Chilton manual is available to cover repairs on your vehicle. You can also use your favorite Internet search engine to find web addresses for those brands of repair manuals. The sites will tell you if a manual is available from them. Next, try Helms, and expect the price to be far higher. Another solution that saves money is to go to your public library and use the Mitchell Manual Online, or other resource the librarian may help you find.
I have a 1987 Ford Bronco II four wheel drive. It had set four a while before being driven and got alot of rust on the braking system. After being driven for a couple of weeks, the front brakes locked up. The left front was the worst and smoked alot. Now the right front is doing the same thing. I had a friend look at it and he said that he could tell that brake fluid was leaking. Also, the calipers were coated with rust. I sprayed rust remover all over them and it helped a little but the right front is still lock up. Not smoking anymore but still rubbing. What can I do?
Getting some rebuilt calipers would be the only really professional solution but you could try and remove the calipers and clean them up if they are the "sliding" type. The rust on the discs is irrelevant to your problem but you can clean those up and check their trueness at the time you do the calipers. It all depends on whether the pistons in the calipers are pitted and rusted or not. If they are, you have no choice but new calipers.
i have a 1995 sedan deville, and i am having some problems one of my problems is I have a leak at the output shaft seal on my transmission. I went and priced the part and is really cheap but i understand that the labor is alot? Secondly my friend pushed the emergency break down and now it won't come back up, could someone please tell me where the emergency break release button is???
I believe you have an automatic brake release that works off engine vacuum. This system has a vacuum release valve under the steering column and also a vacuum servo at the parking brake assembly. It could be simple, like a vacuum hose disconnected under the dash.
The trans leak depends entirely on how much fluid you are losing and if you are willing to check the trans. fluid periodically to make sure the transmission does not run low on fluid. But if the leak is quite small it can go for years like that. If it really starts to leave large puddles under your car (the fluid is dark red in color), then you have to act on it.
It's on the brake pedal itself. I think it's up near the top. If you have an owner's manual, the procedure and a picture is in there.
Be careful with this, when the pedal releases, it could 'whop' your hand.
The overall problem is probably caused by a vacumn hose leak/break/loose, as this is how the release is powered. Check hoses at the pedal, behind the dash, and under the hood on the passenger side.
I do not beleive there *is* a release button for your emo brake pedal. If I recall correctly, on those cars... all you are supposed to do is take xmission out of park and the emo brake releases by itself.
Well, there is a Cadillac Forum website which has downloadable owner manuals in PDF format.
But I have previously been chasticed for posting links to 'competing' sites.
Do a Google search.
And, owners manuals of almost every year are constantly available on eBay.
New ones are possibly still available at Helms, Inc.
And, yes, there is an emergency release on the emergency brake pedal. You just need to get down there with a light and find and pull it.
Here is a cut and paste from a 1997 manual. "Reach under the driver’s side of the instrument panel and pull ont he manual release lever, which is located above the parking brake pedal. If the parking brake does not release, you should either drive to the nearest service station or have your vehicle towed. If your hand or armi s in the way of the pedal, you could be hurt. The pedal springs back quickly. Keep your hand anda rm away when you use the manual release lever. NOTICE: Driving with the parkinbgr ake on can cause your rear brakes to overheatY. ou may have to replace them andy ou could also damagoet her parts of your vehicle."
Thanks guys I found the release thing for the emergency break, but there is still a problem I drove around my parking lot and it still seems as though the breaks are locked specifically the rear brakes. Any idea what this is?
If you have not been using the parking-brake regularly, there is a good chance that the cables are frozen and not allowing the brakes to release.
I ALWAYS use the parking-brake every time I park my cars. I learned very long ago that the cables may freeze up if not used regularly. Besides, many folks say it is not good for the automatic xmission to leave the weight of the car on the parking-pawls.
I was the one that had the title "Front Brakes Locking Up" I tried to take ur advice and replace the calipers but they were so rusted that something broke while trying to take the old ones off. I decided to just get rid of the bronco. I was able to get a trade in value of 800 dollars and I now have a 2002 toyota corrola that i'm making payments on. I'm just saying this to let people know that if ur brakes go out, don't take a chance if it's an old car. just get a better one while you can. brakes can save ur life. just giving some advice.
With rust there is only one way to fix it, and that's tear everything out of there. If your suspension bolts are snapping off during disassembly, you have sort of answered your own question about what to do next. Sounds like you made a good choice for your particular needs and budget.
I have a 1989 Mercury Sable that has sit for a year. I drove the vehical home but now the passenger front disk brake locks up and will not release. I put on new pads and rotors on both driver and passenger side. Brake still locks up. piston moves free both in and out when removed from rotor. Where do I go from here? HELP PLEASE!!!
Some thoughts: make sure your parking brake is off. If brake shoes are adjusted too tight, pull the rubber plugs off the back of the drum and manually back off the shoes with an adjusting tool.
Still stuck? To free stickiness due to rust, tap around the edge of the drum with a rubber mallet. Good luck.
I have been one of those people for over 30 years...while I may park my auto trans car on a level (in my garage) without using the parking brake, all other places use the park brake...
As I understand it, and this may not be literal but an analogy, the auto trans, when placed in Park, jams a pin (pawl) in the gears/bands/whatever to stop the car from moving, or actually to lock up the transmission...whether it stops the car from moving is another story...anyway, as I envision it, when someone parks their car on a hill, and you feel it roll forward 6-8 inches and abruptly stop, this little pin is all that is locking the tranny, and the only thing holding the car from rolling is the shearing strength of that pawl...and it wouldn't take much to shear the pawl and place the tranny effectively into neutral...
I shudder when friends park on a hilly driveway and I watch the car roll over a foot, and no parking brake...it is a miracle that more cars don't break forward and roll...
Just to be anal retentive, I believe it is proper to FIRST apply the parking brake to stop any rolling...once the car is held by the brake, THEN place the car is park, so that the pawl is actually now the secondary brake holding the car, and their is no pressure applied to the pawl, but the pressure holding the car is now the 2 or 4 mini brake shoes inside the rear disc rotor, with sufficient friction to hold the car on a hill...
How some people abuse their cars...those same folks will place the car in reverse, back up at 1,2,3 mph, then slam it into drive, instead of waiting for the car to stop, they use the change of gear to stop the car as it is rolling backwards and then go forward...
It is a wonder that trannies last as long as they do...
That's the correct way to park on hills or inclines, with the only exception being that it's also prudent to turn the front wheels towards the curb if pointing downhill, and away from the curb if pointing uphill. That away even if the brake slips and the pawl fails it won't go very far.
but since we were talking transmissions, I zeroed in on that...but turning the wheel is also something I always do, but it has no effect on the tranny, especially if the pawl shears...altho it will make sure the car goes in circles instead of downhill... :shades:
Both my abs and traction control system failure lights came a few days after my car was rearended. The impact was light and did little damage but I thought is was quite a coincidence. They go off after the car is shut down and seem to come on randomly after driving a few minutes and remain on steadily not blinking. Could this be a result of the crash? Is there a sensor that's shared by both systems that I can test? Has anyone had a similar exprience with a Ford product and was it an expensive repair?
Anything that causes the ABS system to shut off will also disable the traction control system. Start by having any stored ABS trouble codes retrieved with an ABS capable scanner. Probably a wheel speed sensor or it's related wiring.
Hi all, I am new to this forum and need some help. I have a 96' Protege, 1.5L, auto, done 112000 miles. I have a peculiar problem with the brakes. The braking is poor and the pedal almost goes right to the bottom before any decent braking is achieved.To solve this I changed the pads on all 4 wheels and the rotors in april. Since then the car has done only about 5000 miles and the problem has not gone away! It has reduced to some extent, but still quite there. Also in wet conditions braking power is severly compromised. I will be very thankful for any help u experts can give me. Thanks!
has remained on for the past 2 days. The weather has been below freezing lately. Can anyone offer an explanation and/or solution to this problem? Thank you deke33
I am new to the site and figured that I needed to post before spending another $3000 on my 2000 Pontiac Montana Van. I just had the rear wheel cylinders and shoes, and then took it back to replace the master cylinder. The problem is you need to press the brakes down instead of just touching them. (Spongy is the word that my mechanic used) My mechanic was not completely satisfied with the result, so he took it to the dealer and had them check it out. They looked at it and said that what he had done was right, and that if I was their customer they would recommend getting a new ABS motor. My mechanic said that he could get one from the scrap yard and put it on and this would be 1/3 of the cost. The van has 166,000km on it.
Has anyone had a similar problem? If so, do you have any advice?
If one does not TOTALLY REPLACE the brake-fluid every 2 years, the master-cylinder, wheel-cylinders, and the expensive ABS components will corrode from the inside-out. Expensive lesson learned!
However, your description of "spongy pedal" sounds as if there is still some air in the hydrolic system. I am not sure the ABS-motor can cause a "spongy pedal".
An "ABS motor" is part of the Antilock Braking System. It is really an electric hydrolic pump. It provides the ability for the ABS system to apply the brakes independant of the brake pedal by providing hydrolic pressure.
For example, on vehicles that have EDL (Electronic Diffeential Lock), if one wheel starts to slip in the snow, the ABS motor provides hydrolic pressure to gently apply the brakes on the wheel that is starting to slip, that forces the differental to send the engine-torque to the other drive wheel.
Of course, the ABS pump also assists with braking to reduce wheel lock-up.
"An "ABS motor" is part of the Antilock Braking System. It is really an electric hydrolic pump. It provides the ability for the ABS system to apply the brakes independant of the brake pedal by providing hydrolic pressure."
ABS systems absolutely DO NOT apply the brakes, nor can they increase braking pressure to more than the input by the driver through the brake pedal. They use the frequency of the AC voltage signal from the wheel speed sensors to calculate tire slip relative to vehicle speed, then modulate (REDUCE) brake pressure to the skidding wheel to prevent wheel lockup. Most systems are calibrated to allow about 15% tire slip to provide the best combination of steerability, lateral control, and reduced stopping distance. The only pump used in any discreet ABS system is the one used to return brake fluid from the accumulators back to the master cylinder.
Vehicle stability systems and traction control systems, however, do have the capability of applying the brakes selectively as required via an electro-hydraulic pump.
With all due respect Mr alcan... The question was asking what a "ABS motor" is.
I know for a FACT that what I described above is how the systmes work on my automobile. When the ABS system activates on my vehicle (aka braking too hard on ice) I can HEAR the ABS motor activate and FEEL the brake-pedal pulsating as it modulates the hydrolic pressure in the system.
I will grant you that some cheeper ABS systems only have the ability to bleed brake pressure to reduce wheel lock-up.... but thoses systems DO NOT HAVE an ABS motor. (just have an accumulator resivour to bleed the pressure into and a electric-hydrolic valve to meter it) After the brake pedal is released, the accumulated pressure simply bleeds back into the system into the master cylinder. The accumulator is essentually spring-loaded. (there is no pump required)
Back to the original discussion.... about a "spongy pedal" If air gets into the accumulator, it is often hard to get it all out. This may cause "spongy pedal" condition. Replacing parts is not the proper way to fix this condition.
"I will grant you that some cheeper (cheaper?) ABS systems only have the ability to bleed brake pressure to reduce wheel lock-up.... but thoses systems DO NOT HAVE an ABS motor. (just have an accumulator resivour to bleed the pressure into and a electric-hydrolic valve to meter it"
Uh huh, the older design Kelsey Hayes RWAL systems fitted to domestic light trucks.
To suggest that any conventional ABS system is capable of applying the brakes demonstrates a fundamental lack of understanding of how the systems operate. Of course you hear a pump running, it's returning fluid from the accumulators to the master cylinder.
For the record, I've been teaching the construction, operation, components and diagnosis of ABS systems for about 15 years. During that time I've attended pretty much every system manufacturer's training and system update seminars including Bosch, Teves (ATE), Kelsey Hayes, Delco and Delphi. It's my business to stay updated and disseminate the latest accurate, factual information to technicians.
Thank you. Though it is sleeting out the weather has warmed overnight. When I went out to start my car defrosting the brake light remained off. I will check the fluid as soon as daylight comes. As to the brake pads, the car was just inspected less than 40 days ago, and I was told the pads were in good shape. Thanks for your assistance.
That makes sense to me... I can only relate to my pickup truck with RWAL and my VW with the ability to apply any wheel brake at will....thus that is what I was discussing.
With your obviously advanced knowledge of ABS systems, can you offer any words of wisdom to the person that is having issues with "spongy pedal"? Do you think that replacing the "ABS motor" is a reasonable approach to this problem?
With my years of real-world repair knowledge, I still maintin that "spongy pedal" reflects that there is air in the hydrolic system. I am wondering if they hooked it up to the computer to "manuually" operate the ABS motor and purge the air. Many cars need this step to be performed to fully purge air from the ABS components.
A spongy pedal is usually caused by air in the system, but can also be caused by a problem in an ABS pressure modulator. If contaminants prevent the dump solenoid from completely closing, when the brake pedal is depressed fluid can leak into the accumulator, stroking the accumulator piston against it's spring. Simple to diagnose, first remove both lines from the master cylinder and cap the ports with block off plugs. If the pedal's still soft, the m.c. is dinked. If the pedal's ok, reinstall the lines one at a time to determine which circuit has the problem then block off the outlet from the pressure modulator for the affected circuit. If the pedal's firm now, the modulator's probably leaking internally.
Re bleeding systems with ABS, usually not a problem unless the pressure modulator has been replaced. For problem cars when I don't have a bi-directional ABS scanner handy I'll pressure bleed, take the car to a safe area and perform several ABS stops, then pressure bleed again.
Should we assume that pressure bleeding in this case is done by stepping on the brake pedal rather than by using a hand pump at the wheel, or some third means?
No. You're referring to manual bleeding. Pressure bleeders work by pressurizing the master cylinder reservoir to push fluid through the system. This is the one I use:
An adaptor attaches to the master cylinder reservoir, quick connect from the pressure bottle hooks up to it, and the air source hose goes to the valve of the left front tire. Set the regulator to 10-15 p.s.i. then open the bleeders one at a time. Simple, fast hookup and works great. I spent a lot of years twisting wrenches in dealerships before changing careers, and this is the best pressure bleeder I've ever used. The only vehicles I've run into where it doesn't work are earlier Caravans with the separate filler neck for the m.c. reservoir. Can't pressurize the reservoir.
Vacuum bleeding at the bleeder screws is a PITA because there'll always be some air bubbles in the drain hose due to air being pulled in past the bleeder screw threads, so you can never be sure that all the air's out. I've tried removing the bleeders and coating the threads with silicone grease to prevent this, doesn't work.
Manual bleeding through the pedal can overstroke the m.c. pistons and damage their cup seals if there's any corrosion in the nether regions of the bore. This is also why I tell every basic level brake class I teach that if they get one in with a blown flex hose or a line rusted through, to advise the customer that it might need a master cylinder if they can't get a pedal after the repair's done. Not uncommon for m.c. seals to be damaged the first time that pedal went down when the hose/line let go.
I have 2 Camry's (1993 & 2003) and have experienced occasional squeaking in both. Not 100% of the time, but enough to get annoyed.
This happens even after new brakes are installed. The shop has sprayed something on them but the noise comes back and is most noticeable when the car is first used. It happens sometimes even after use, again not 100% of the time.
Disc brake squeal is almost always caused by the pads vibrating against the rotors, which is transmitted into the pad support plates and heard as a squeal. All anti-squeal shims and springs must be present, as shown here:
When I hit the brakes with a little ump, I feel like Im on Ice. Or if Im slowing down and my wheels bounce a little, Im in the intersection. Changed shocks, bleed brakes, replaced and inspected brake pad and calipers. Common brake garage tells me to take it to a dealer. May have to. Any Ideas out there?
When I apply the brakes on dry pavement the pedal travel is normal until just before the van stops. Then the pedal suddenly drops and the brakes catch with what feels like a 1 or 2 step fast pulse - almost like what it feels like when the ABS activates on wet/slippery surface. Sometimes there will be a fast clicking/pumping(?) noise coming from the engine compartment after it is completely stopped and even continuing to drive away from the stop. A brake shop drove the van and want to change front pads, rear shoes, calipers, rotors, wheel cylinders & drums and pressure bleed the system. The $700 price has slowed my decision down. I replaced the front pads as a starting point but the problem remains. I can do the work the shop wants to do but I'm wondering if this is an ABS problem, which I'm really not familiar with. Any help would be appreciated.
It sounds exactly like an ABS system going into self-test just before stopping. First thing to check is the front wheel speed sensor reluctor rings for cracks. They're thin toothed rings pressed onto the outer housing of the outer CV joints. Corrosion builds up under them and causes them to split, increasing the distance between the 2 teeth straddling the crack. Causes the system to go into self-test at low speed. If you find a cracked one, they're available separately. No need to replace the entire halfshaft.
Comments
Thanks all.
I'm looking to redo my brakes on my Galant, and need to know how to get a detailed instruction manual. I've been reading through some of the threads, and it looks like you get what you pay for, so I'm hoping to go with the Raybestos QS style. Is there anything I need to know before attempting this as a first timer?
Remember your brakes are life saving devices.
The trans leak depends entirely on how much fluid you are losing and if you are willing to check the trans. fluid periodically to make sure the transmission does not run low on fluid. But if the leak is quite small it can go for years like that. If it really starts to leave large puddles under your car (the fluid is dark red in color), then you have to act on it.
Be careful with this, when the pedal releases, it could 'whop' your hand.
The overall problem is probably caused by a vacumn hose leak/break/loose, as this is how the release is powered. Check hoses at the pedal, behind the dash, and under the hood on the passenger side.
But I have previously been chasticed for posting links to 'competing' sites.
Do a Google search.
And, owners manuals of almost every year are constantly available on eBay.
New ones are possibly still available at Helms, Inc.
And, yes, there is an emergency release on the emergency brake pedal. You just need to get down there with a light and find and pull it.
Here is a cut and paste from a 1997 manual.
"Reach under the driver’s side of the instrument panel
and pull ont he manual release lever, which is located
above the parking brake pedal. If the parking brake does
not release, you should either drive to the nearest service
station or have your vehicle towed.
If your hand or armi s in the way of the pedal,
you could be hurt. The pedal springs back
quickly. Keep your hand anda rm away when you
use the manual release lever.
NOTICE:
Driving with the parkinbgr ake on can cause
your rear brakes to overheatY. ou may have to
replace them andy ou could also damagoet her
parts of your vehicle."
I can't get the image to paste.....
I ALWAYS use the parking-brake every time I park my cars. I learned very long ago that the cables may freeze up if not used regularly. Besides, many folks say it is not good for the automatic xmission to leave the weight of the car on the parking-pawls.
Still stuck? To free stickiness due to rust, tap around the edge of the drum with a rubber mallet. Good luck.
Dave
As I understand it, and this may not be literal but an analogy, the auto trans, when placed in Park, jams a pin (pawl) in the gears/bands/whatever to stop the car from moving, or actually to lock up the transmission...whether it stops the car from moving is another story...anyway, as I envision it, when someone parks their car on a hill, and you feel it roll forward 6-8 inches and abruptly stop, this little pin is all that is locking the tranny, and the only thing holding the car from rolling is the shearing strength of that pawl...and it wouldn't take much to shear the pawl and place the tranny effectively into neutral...
I shudder when friends park on a hilly driveway and I watch the car roll over a foot, and no parking brake...it is a miracle that more cars don't break forward and roll...
Just to be anal retentive, I believe it is proper to FIRST apply the parking brake to stop any rolling...once the car is held by the brake, THEN place the car is park, so that the pawl is actually now the secondary brake holding the car, and their is no pressure applied to the pawl, but the pressure holding the car is now the 2 or 4 mini brake shoes inside the rear disc rotor, with sufficient friction to hold the car on a hill...
How some people abuse their cars...those same folks will place the car in reverse, back up at 1,2,3 mph, then slam it into drive, instead of waiting for the car to stop, they use the change of gear to stop the car as it is rolling backwards and then go forward...
It is a wonder that trannies last as long as they do...
Is there a sensor that's shared by both systems that I can test? Has anyone had a similar exprience with a Ford product and was it an expensive repair?
I am new to this forum and need some help. I have a 96' Protege, 1.5L, auto, done 112000 miles. I have a peculiar problem with the brakes. The braking is poor and the pedal almost goes right to the bottom before any decent braking is achieved.To solve this I changed the pads on all 4 wheels and the rotors in april. Since then the car has done only about 5000 miles and the problem has not gone away! It has reduced to some extent, but still quite there. Also in wet conditions braking power is severly compromised.
I will be very thankful for any help u experts can give me.
Thanks!
deke33
I am new to the site and figured that I needed to post before spending another $3000 on my 2000 Pontiac Montana Van. I just had the rear wheel cylinders and shoes, and then took it back to replace the master cylinder. The problem is you need to press the brakes down instead of just touching them. (Spongy is the word that my mechanic used) My mechanic was not completely satisfied with the result, so he took it to the dealer and had them check it out. They looked at it and said that what he had done was right, and that if I was their customer they would recommend getting a new ABS motor. My mechanic said that he could get one from the scrap yard and put it on and this would be 1/3 of the cost. The van has 166,000km on it.
Has anyone had a similar problem? If so, do you have any advice?
Thanks!
Expensive lesson learned!
However, your description of "spongy pedal" sounds as if there is still some air in the hydrolic system. I am not sure the ABS-motor can cause a "spongy pedal".
For example, on vehicles that have EDL (Electronic Diffeential Lock), if one wheel starts to slip in the snow, the ABS motor provides hydrolic pressure to gently apply the brakes on the wheel that is starting to slip, that forces the differental to send the engine-torque to the other drive wheel.
Of course, the ABS pump also assists with braking to reduce wheel lock-up.
ABS systems absolutely DO NOT apply the brakes, nor can they increase braking pressure to more than the input by the driver through the brake pedal. They use the frequency of the AC voltage signal from the wheel speed sensors to calculate tire slip relative to vehicle speed, then modulate (REDUCE) brake pressure to the skidding wheel to prevent wheel lockup. Most systems are calibrated to allow about 15% tire slip to provide the best combination of steerability, lateral control, and reduced stopping distance. The only pump used in any discreet ABS system is the one used to return brake fluid from the accumulators back to the master cylinder.
Vehicle stability systems and traction control systems, however, do have the capability of applying the brakes selectively as required via an electro-hydraulic pump.
I know for a FACT that what I described above is how the systmes work on my automobile. When the ABS system activates on my vehicle (aka braking too hard on ice) I can HEAR the ABS motor activate and FEEL the brake-pedal pulsating as it modulates the hydrolic pressure in the system.
I will grant you that some cheeper ABS systems only have the ability to bleed brake pressure to reduce wheel lock-up.... but thoses systems DO NOT HAVE an ABS motor. (just have an accumulator resivour to bleed the pressure into and a electric-hydrolic valve to meter it) After the brake pedal is released, the accumulated pressure simply bleeds back into the system into the master cylinder. The accumulator is essentually spring-loaded. (there is no pump required)
Back to the original discussion.... about a "spongy pedal" If air gets into the accumulator, it is often hard to get it all out. This may cause "spongy pedal" condition. Replacing parts is not the proper way to fix this condition.
Uh huh, the older design Kelsey Hayes RWAL systems fitted to domestic light trucks.
To suggest that any conventional ABS system is capable of applying the brakes demonstrates a fundamental lack of understanding of how the systems operate. Of course you hear a pump running, it's returning fluid from the accumulators to the master cylinder.
For the record, I've been teaching the construction, operation, components and diagnosis of ABS systems for about 15 years. During that time I've attended pretty much every system manufacturer's training and system update seminars including Bosch, Teves (ATE), Kelsey Hayes, Delco and Delphi. It's my business to stay updated and disseminate the latest accurate, factual information to technicians.
With your obviously advanced knowledge of ABS systems, can you offer any words of wisdom to the person that is having issues with "spongy pedal"? Do you think that replacing the "ABS motor" is a reasonable approach to this problem?
With my years of real-world repair knowledge, I still maintin that "spongy pedal" reflects that there is air in the hydrolic system. I am wondering if they hooked it up to the computer to "manuually" operate the ABS motor and purge the air. Many cars need this step to be performed to fully purge air from the ABS components.
Re bleeding systems with ABS, usually not a problem unless the pressure modulator has been replaced. For problem cars when I don't have a bi-directional ABS scanner handy I'll pressure bleed, take the car to a safe area and perform several ABS stops, then pressure bleed again.
http://www.speedibleed.com/products/completekit2.php
An adaptor attaches to the master cylinder reservoir, quick connect from the pressure bottle hooks up to it, and the air source hose goes to the valve of the left front tire. Set the regulator to 10-15 p.s.i. then open the bleeders one at a time. Simple, fast hookup and works great. I spent a lot of years twisting wrenches in dealerships before changing careers, and this is the best pressure bleeder I've ever used. The only vehicles I've run into where it doesn't work are earlier Caravans with the separate filler neck for the m.c. reservoir. Can't pressurize the reservoir.
Vacuum bleeding at the bleeder screws is a PITA because there'll always be some air bubbles in the drain hose due to air being pulled in past the bleeder screw threads, so you can never be sure that all the air's out. I've tried removing the bleeders and coating the threads with silicone grease to prevent this, doesn't work.
Manual bleeding through the pedal can overstroke the m.c. pistons and damage their cup seals if there's any corrosion in the nether regions of the bore. This is also why I tell every basic level brake class I teach that if they get one in with a blown flex hose or a line rusted through, to advise the customer that it might need a master cylinder if they can't get a pedal after the repair's done. Not uncommon for m.c. seals to be damaged the first time that pedal went down when the hose/line let go.
This happens even after new brakes are installed. The shop has sprayed something on them but the noise comes back and is most noticeable when the car is first used. It happens sometimes even after use, again not 100% of the time.
Any clues?
Albie
http://www.autozone.com/images/cds/gif/large/0900823d8013f8c0.gif
If all the anti-squeal hardware is there and in good shape, the rotors will require refinishing.
Ice. Or if Im slowing down and my wheels bounce a little,
Im in the intersection. Changed shocks, bleed brakes, replaced and inspected brake pad and calipers. Common brake garage tells me to take it to a dealer. May have to.
Any Ideas out there?