Newbie - Brake pedal drops on 2002 Accord EX V6

[retired1]

MAINTENANCE PERFORMED: I just replaced all the brake components on both sides of the front of my 2002 Accord EX V6. Brake components means: rotors, calipers, pads, and the rubber brake line hoses between the steel brake lines and the calipers. To maximize the benefit of this brake work, I installed a new master cylinder. All old brake fluid in the brake system (front and back) was removed and replaced with new DOT 3. A thorough bleeding of the brakes was done at all 4 calipers ....... there is no air in the system, as the system was thoroughly bled AFTER the master cylinder was installed.

 

PROBLEM: When I press on the brake pedal with the engine turned off, I have a full, solid pedal. This gives me confidence the parts of the brake system that contain brake fluid are in good shape. When I turn the key on without starting the engine, the brake pedal continues to remain solid. But ...... when I start the engine, the brake pedal loses the solid feeling and as long as I am pressing it, it drops substantially with no obvious pressure applied to the brake system. The brake pedal will drop about 2 inches and then the solid feeling in the brake pedal returns. So what could be causing the pedal to drop so far? It was not doing this prior to the work I did on the front brakes. THE DROP IN THE BRAKE PEDAL WAS OCCURRING ON THE OLD MASTER CYLINDER, BUT IT STARTED ONLY AFTER I PERFORMED ALL THE WORK ON THE FRONTBRAKES.

 

NOTE: Once the brake pedal drops about 2 inches, it will stop the vehicle without any difficulty.

 

Any comments from anyone? Thanks. Joe

[Cuba Rodriguez]

did you bench bleed the master cylinder before install? also when bleeding entire system after, did you start from the furthest to the nearest ("z" pattern -right rear, left rear, right front, left front)....if you have a solid pedal with car off that eliminates the brake booster.... but the symptoms you describe, from my own experience, are that there is air still in the system or faulty master cylinder.

 

Once you bled with everything on car, did you bleed using buddy system? hands down would be the best way... the vacuum pumps, etc I found always to be useless.

[retired1]

Thanks for the comment.

 

Yes, I bench bled the master cylinder before I installed it. As to the bleeding pattern, as I understand the factory specs the driver's side front is to be bled first, then the passenger's side front. Next, the right rear is bled, and the left rear. Again, I followed what I understand to be Honda's directions for bleeding the brakes on the 2002 Accord.

 

I doubt that the problem is with the master cylinder. The master cylinder that was on the car when I started the brake job was doing the exact same thing that the new one is doing ...... the brake pedal is dropping about 2 inches when the engine is started.

 

If there was air in the system, I should be getting somewhat of a soft pedal, which I am not. The only problem I have is the pedal dropping when the engine is started.

 

Yes, I used the buddy system to bleed the brakes. Although, I have found that a vacuum pump can work well if you remove the bleeder valve from the calipers, cover the threads in a heavy grease and screw it back in. The heavy grease will usually eliminate air being sucked in around the threads and creating a constant stream of bubbles in the clear hose leading to the vacuum pump.

 

The brakes act as though there is a reservoir of some kind in the brake system that is being filled by pulling brake fluid out of the rest of the brake system when I start the engine. When I shut the engine off, the brake fluid returns to the system (master cylinder). The brake fluid that is in the master cylinder when the engine is not running has to be going somewhere when the engine is started...... This is extremely frustrating, I have never before experienced a problem like this.

 

Is there any part of the ABS that might have enough brake fluid capacity to pull, and hold, the brake fluid out of the rest of the brake system when the engine is started?

 

Thanks. Joe

[Cuba Rodriguez]

The ABS module and its components should never be touched outside of dealer or without dealer equipment...the electrical parts inside need to be activated by dealer scanner to bleed the ABS module portion properly.....I've managed to do many brake hyrdaulic work (calipers, master cylinders, wheel cylinders, lines, etc) on different vehicles with ABS -and never have an issue myself

 

Another thing you can try is remove lines to master cylinder and put plugs in their place, then pump the pedal to make sure it's hard and good feeling. Reconnect lines then clamp off one by one each brake hose and see when pedal becomes firm again, to try and eliminate or which wheel to focus on? If that makes sense.

 

I find it so odd that you are having such an issue. It sounds like you know what you are doing and have done everything right. I can't even come up with any other theories or explanations and hope someone else may chime in to offer something different. I also find it strange on how Honda's procedure of bleeding is totally different from what I've learned and used over the years ~but shouldn't be too big of a deal overall.

 

If somehow you come across the answer or figure it out, PLEASE update.... I really am interested on the answer.

[James Matteu]

Sounds like air in the braking hydraulics.

 

Also, I've never heard of that bleed procedure. 'Cuba' has it right as I know it, which also jives with the Helm literature I have.

 

I have a question. What on earth happened that you replaced so many components in what you have given the impression to be a short span of time.

 

I don't use a buddy system or vacuum pump or greasy bleed bolts. I take a short length of hose and stick it on the bleed screw, then drop the open end in a jar with enough brake fluid to submerge the hose end. I open the bleed screw then slowly pump the brake. When I don't see any air coming from the bleed screw, I tighten the bleed screw and move on to the next one. I refill the reservoir as needed. Don't let the reservoir run dry or you have to start over.

 

I've also replaced my ABS hydraulic fluid (brake fluid) and bled that system. I don't know about the newer systems, but my old school Nissin ALB-3 is pretty low tech where Honda's diagnostic module really isn't needed. I use a jumper wire to make the run circuit hot tobleed and flush the ABS module and then while parked I start my car a few times to run the ABS system through its pressure up sequence; that charges up my accumulator, opens the relief valve venting any air back to the ABS reservoir, and toggles the solenoids inside the ABS module so any trapped air is shoved into the regular braking hydraulics. Then I bleed the regular system if it feels spongy or if my brake pedal has the kind of travel you described in your first post.

 

So I wouldn't go as far as saying you should never touch ABS components, unless you don't know what you're dealing with, then I would say take it to a dealer.

[retired1]

Thanks to both of you for the comments. As to what led to a major overhaul of the front part of the brake system, it was initiated with a sticking caliper on the driver's side. I was about a hundred miles from home in another city and was on and off the freeway several times, thus several speed ups, and slow downs, and slowing from about 70 miles an hour to exit the freeway. (In other words, the brakes were getting quite a workout, even though I do not drive fast, and I avoid slamming on the brakes unless it is 100% necessary.) On one of the attempts to get off the freeway I heard the unwanted grinding of metal on metal...... no doubt what it was. I pulled into a parking lot ASAP and looked at the outside of all the rotors through the holes in the rims.... the outside of the left front rotor (driver's side) had substantial degradation ..... the kind that happens when a disk pad wears out and the metal backing on the pad gets into the rotor.

 

I jacked up the car, took the wheel off the driver's side and it was obvious to me that the caliper had been sticking and had caused the outside pad on that side to get eaten up. (This is when you get that awful feeling.... not at home, and a serious problem with the car...... and only a few tools in the trunk.) Anyway, I replaced the left front wheel and proceeded to jack the car up and check the rotors, and brake pads as best I could, on all the other wheels. Everything else looked ok. Next up, I headed home immediately, which fortunately was virtually all freeway driving until within a few miles of home ...... no need for braking.

 

When I got home, I proceeded to remove the rotor and caliper from the driver's side of the car. I had to really exert a lot of pressure on my C-clamp to get the caliper piston backed off. When I got the cailper off I opened it up. There was some blackish, rubbery material in the piston chamber that was causing the caliper piston to stick. The most likely source of the blackish material was from the rubber brake hose. So ....... to maximize the quality of the brakes on the driver's side of my car, and to hopefully eliminate future problems, I purchased: brake pads, a new rotor, a new caliper, a new rubber brake hose, and a large can of DOT 3 brake fluid. Installing the new brake components and bleeding the brakes was quick and easy. After pressing the brake pedal a few times to make sure the new caliper was retracting sufficiently from the rotor, and that I had a "full" brake pedal, I put the tire back on the car and away I went for a test drive in the neighborhood. AT THIS POINT THE BRAKE PEDAL WAS NOT DROPPING WHEN THE ENGINE WAS RUNNING.

 

After driving around the neighborhood a bit, I could not feel any heat build-up on the new rotor.... the caliper must be working just fine. So.... away I went for a drive on the freeway. Everything seemed fine until I pulled back in the driveway and started touching the rims with my hands checking for heat. Sure enough, there was no substantial heat on the rim or the rotor I had just replaced, nor were the rear rims or rotors heating up. However, the rim on the front passenger side was almost "hot". Using my lazer pointer heat "thermometer" (that looks like a small pistol) the right front rotor was registering about 130 degrees, about 25 degrees greater than the other rotors. The only logical explanation for the elevated heat on the "hot" rotor had to be caused by the caliper on that side either exerting too much pressure on the rotor (not likely) or another sticking caliper.

 

So.... here we go again. Jack the right front passenger side of the car up and remove the caliper and brake pads. Yep, this caliper was a bit too hard to push back to suit me. DECISION TIME: Do I want both sides of the brakes on the front of my car to be working in perfect order? ABSOLUTELY! Next up, I get out my magnetic base and my travel indicator.... sure enough, spinning the rotor caused the indicator needle to move too much for me. Most people probably would not have been concerned with a slightly warped rotor, but I don't care for one on my car..... and I do not like rotors that have been thinned by turning. Back to the auto supply store: another new rotor, another set of disk pads (the other ones still had half-life), and a new caliper. By this time, I am getting concerned about the breaking down of the inside of the rubber brake hoses, so I also purchased another new rubber brake hose.

 

Putting all the new parts on the right front passenger side was even faster than the driver's side.... I learned all the little dos and do nots on the driver's side. So, now we have my nice little Accord all fixed up with all new brake parts on the front. What can possibly go wrong? So, back to the neighborhood test driving.... no obvious problem, and no heat build up, so away we go on the freeway...... but at the minimum speed possible and taking it easy on the braking until I am 100% satisfied that all is well. Back to the driveway at home, no heat from any of the rims or rotors, and finally time to relax and brag about my superior brake work. Then I discovered there were no bottle of cold pop, or water, in the refrigerator. So I have to make a quick trip to the convenience store..... a man has to have his beverage, even if it is just pop, or water.

 

I hop in the car, put my foot on the brake pedal, start the car, and then I noticed the drop in the brake pedal. It is quite possible it dropped when I was test driving the car, but if it did, I just did not notice. After agonizing for a while, I decided to again bleed the calipers at all 4 wheels..... that was a wasted endeavour. Then I went through a series of recommended tests that supposedly verify the integrity of the brake booster.... no problem with the brake booster. OK, al that can be wrong is a problem with the master cylinder. Back to the auto supply store for a a new master cylinder, and some more brake fluid. Bench bleed the new master cylinder, and install it. Then again bleed the entire brake system at all 4 wheels. The new master cylinder did not help at all. Without starting the engine the pedal is full and firm. Start the engine and the pedal drops. Once it drops it again becomes firm and the brakes easily stop the car. AND THAT IS WHERE I AM WITH MY CAR'S BRAKES....AND HOW I GOT TO THIS POINT.

 

When I was young I worked in factories with hydraulic systems that punched holes in things, bent things, and lifted and moved things. From working with hydraulic systems I know that hydraulic fluid just does not disappear from a closed system and then reappear (as it appears to be doing in my master cylinder). Every hydraulic system that I have worked with has a force applied to the fluid by a pump of some kind and the fluid is normally pushed to accomplish a task, and then pulled, or routed back to be pushed again..... basically, that is exactly what happens in a car's hydraulic braking system. The fly in the ointment in a car's hydraulic brake system may just be the ABS system.

 

I now have a schematic of the brake lines and the ABS modulator assembly that I got from a real nice parts guy at a Honda dealership parts counter. There appears to be only a few parts in the brake system that are effected by the car's engine being started: the brake booster, which uses the engine's vacuum, and the ABS system which receives signals from each wheel and, when needed, decreases the brake fluid pressure to a wheel that is "locking up". Since the brake booster does not accept any brake fluid from the master cylinder, we have to dismiss it as the culprit. That leaves us with the ABS modulator assembly.... the only place that can possibly be accepting the brake fluid that is leaving the master cylinder when the brake pedal drops..... or so it seems. So, that leaves me with a question for anyone knowledge about the ABS modulator assembly and how it works. How about Cuba, or Mark.... you two seem to know about these things. My question, or questions: (1) When I removed the brake components on the front of the car, and opened the hydraulic brake system, is it likely that I let air get into the system that likely worked its way to the ABS modulator assembly and is still in there? The ABS modulator assembly is on the right side of the car. The steel brake line that leads from the ABS modulator assembly to the top of the rubber brake hose on the passenger side is rather short.... not a long distance for air to travel.

Next question: (2) Once air gets into the ABS modulator assembly, is it possible that the air can, or will, stay in the assembly and will not come out when the brakes are bled at the calipers? The big question: (3) If there is air in the ABS modulator assembly, when the car's engine is running will the ABS light on the inside of the car turn off as it normally does after a couple of seconds?

 

Sorry for writing a book, but hopefully when this issue is resolved others will learn something from it. Joe

[James Matteu]

Where did the rubber come from and where exactly did you find it? Are you talking about the concave portion of the caliper piston or did you remove the piston from the caliper to inspect the caliper internals? Did you find damage to the brake softlines?

 

The hydraulic systems you worked on is analogous to the brake system here. The line to caliper pressure is fixed but the Brake Master Cylinder does return internal pressure to the reservoir, pressure is provided by foot + brake booster.

 

1) Its isnt just likely, im sure you have air in the system. No, the air didnt work its way into the ABS Modulator since the air would have to have magically seeped passed a solenoid designed to seal off high pressure brake fluid and when the solenoid is open the line is open to the high pressure side of the modulator where the accumulator is set at too high of an operating pressure to allow anything in, remember the relief valve is set at 5000psi which far exceeds the line pressure outside the ABS Modulator.

2) bleeding brakes at the caliper has nothing to do with bleeding the modulator, the two side of that system are separated by the solenoids I mentioned before.

3) yes, until air moves into the accumulator, then the motor will run too long and generate a fault code and trigger the cut relay.

 

 

 

 

Conclusion: you trapped air in your braking system in the process of intalling all those new components. I wonder if you primed the new calipers and lines before closong the system so that bleeding wouldn't be such an uphill battle. You have some more bleeding to do.

 

Leave your ABS alone.

[Cuba Rodriguez]

@Retired1 -yes, as far as read so far on both newer posts... I feel James is correct and I would concur on 1,2,&3 on the latest post...

I also tend to believe that there is air still trapped as well using the logic James and Retired1 stated (I loved the detail, andwith the symptom you described, air) in your last post. How much brake fluid did you go through so far in trying to bleed out entire system (you mentioned you bled back too I believe)? About 1 quart? To bleed right it would take about that much if not little more and get old fluid out.

Like I mentioned before the only other possibility would be a defective Master Cylinder... seal intermittently gets stuck.

 

.

@James -the older ABS could be bled without scanner assistance but now from Hondas 98 or 99 (I believe those are the years Honda changed that) to present date won't activate without the scanner.

[retired1]

James: The "rubber" material, which was a material closely akin to extremely finely ground rubber, was inside the caliper in the "wet" area behind the piston. I put some of this "stuff" on a flat piece of metal and mashed on it with my finger and it felt like rubber. There was nothing else of substance in the wet area of the caliper, and once I cleaned the "stuff" out of the chamber in the caliper the piston would move freely back and forth in the chamber in the caliper. I thought about getting a rebuild kit and repairing the caliper and reinstalling it. However, the newer automobiles seem to be so sensitive to the most minor problem I decided to install a new caliper and eliminate concerns about the caliper. I AM EXTREMELY CONCERNED ABOUT THE RISKS WE ALL FACE ON THE HIGHWAYS THESE DAYS, AND I JUST WANT TO MAXIMIZE MY SAFETY AND DO EVERYTHING REASONABLE TO AVOID CAUSING OTHERS HARM ON THE BOULEVARD. WITH THE EXCEPTION OF THE LEFT FRONT CALIPER STICKING I HAVE ALWAYS MAINTAINED VERY GOOD BRAKES ON MY VEHICLES. WHEN MY BRAKE PADS OR SHOES REACH HALF-LIFE, AT THE FIRST OPPORTUNITY I REPLACE THEM.

 

I am reasonably confident that the rubbery material came from the rubber brake hose. With all the cheap junk products that are coming from China these days, we never know for sure what we are buying. The last time I replaced the brake pads, and drained the brake fluid, I might have been sold some inferior brake fluid that degraded the inside of the rubber brake lines. I NEVER BUY CHEAP BRAKE FLUID, OR BRAKE COMPONENTS, BUT THAT DOESN'T MEAN I GET THE QUALITY I PAY FOR. I really do not know if the rubber brake lines were bad, but I know the ones now on the car are good.

 

PURE TRIVIA: About 2 years back I purchased one of those 5 HP Honda knock-off engines from Harbor Freight to repower an older garden tiller. The ethanol in the gas destroyed the black rubber gas line on the 5 HP engine. This occurred even though I always treat my tiller gas with anti-ethanol liquid. The degraded gas line material was so fine it worked its way pass the needle valve on the float assembly and most of it settled in the bowl on the carburetor (....and the rest got sucked into the caburetor's venturi tube). The rubber-like material in the caliper looked very similar to the material that was in the bowl on the carburetor.

 

James, thanks for the info. about the ABS. I have no intention of "tinkering" with it. The suggested retail price of a new ABS modulator assembly for my car is over $2,000. When I add in 8.25% sales tax, cost alone is enough of a reason leave the ABS alone.

 

Cuba: I have bled the brakes so many times, at this point I really do not know how much brake fluid I used each time I bled them. Be that as it may, since James has made it clear that it is quite likely that the ABS is not the problem, I will again turn my attention to bleeding the brake system.

 

It may be a couple of days before I will have an opportunity to again bleed the brakes. Once I am certain that I have thoroughly bled the brake system, I will report back here on what has happened.

 

Thanks to James and Cuba. Joe

[Cuba Rodriguez]

oh goodness.... I totally agree with you Retired1, the cheap quality parts from china absolutely kill me anymore (hate to know we no longer as a country manufacture anymore and gave away our jobs to other countries and quality has never been the same) and I always purchase top of the line (however not as good as they once were either). Harbor Freight, ugh! don't get me started...lol. And then this with this "ethanol" additive has been killing GAS motors (all types from lawn to car), totally shouldn't be there, and in fact it takes the same amount of oil/petrol (let's say 1 gal) to make the machines operate to make same amount (1 gal) of "ethanol" which makes gas motors run worse anyway....How is that helping the economy?? Sorry, off topic but had to put that out there.

 

How frustrating! I feel you have done everything right, and I hope through all your perserverance you will finally triumph in the end. Such an "easy" job to give you so much trouble mind boggles me. Hope to read good news later (even if couple days)

[retired1]

IMPORTANT SAFETY RELATED ISSUE:

 

The rubber brake lines that were removed from my car have a bracket FIRMLY ATTACHED on the outside of the rubber brake lines in approximately their middle. This bracketS attach to the large, heavy, thick, vertical metal piece directly behind the wheel and somewhat level with the bleeder valve on the calipers. (Similar rubber brake lines appear to have been installed on cars at this location on cars for a very long time.) This bracket keeps the rubber brake line out of harms way and away from the wheel when the car is being turned left or right, and when the wheel is rotating as the car moves down the road.

 

I am placing big emphasis on "FIRMLY ATTACHED". The brackets were installed in a factory somewhere and were clamped on tightly. The bracket was clamped on tight enough that the rubber hose will not slip through the bracket, nor can the rubber hose be pulled through the bracket. Honda engineers obviously realized that the rubber hose must not slip back and forth through the bracket when the car is turned left or right, or as the car moves down the road and the wheel moves up and down as it incurs bumps and dips in the road. Any movement of the hose in the bracket would wear the outside of the rubber hose. Even normal vibrations that occur while a car is being driven would be detrimental to the outside of the hose where the bracket is located. WE ARE ADDRESSING A SAFETY ISSURE HERE.

 

When attempting to buy the replacement rubber hoses at the local auto supply parts store the first thing I noticed was that most of the hoses will slip through the brackets. The brackets on these hoses are clamped on the hose in an obvious attempt to keep the hoses from slipping through the brackets, but on most of the hose/bracket assemblies, the quality inspection must not have been up to par..... the hoses could be pulled through the bracket. On some of the hose/bracket assemblies the hoses were rather difficult to pull through the bracket, on others they slid through with virtually no resistance. Common sense tells me that these inferior hose/bracket assemblies create a safety hazard. When the outside of a hose wears where it slides back and forth in a bracket the wear will continue.... and continue.... and continue. Then one day a driver slams on the brakes, the hose ruptures at the wear point in the bracket, and an accident kills the driver and a few other people. (when my children were growing I used to tell them that accidents must be prevented. After an accident, if you are killed, your are DEAD. Once your are dead it really doesn't make much difference who, or what, caused the accident. IF YOU ARE DEAD, YOU ARE DEAD! Sorry for the philosophy, but I am a nut about safety as I was not given the right to do anything that kills another person.)

 

OK. Any comments, thoughts, etc. about the "loose" brackets on the rubber brake hoses. MY ADVICE IS TO BUY THES ASSEMBLIES AT A HONDA DEALERHSIP.

 

Thanks to those that took time to read this. Joe

[James Matteu]

That bracket does keep the hose in place but the movement described as a result of the bracket being loose is a bit of a stretch. Ive worked on a 2012 Dodge Avenger which had a lose bracket from factory. Ive worked on a 2006 Pontiac Vibe which had a lose bracket from factory. Ive worked on a 2005 Nissan Altima 2.5 that had a lose bracket from factory. Ive replaced my 1997 Honda Accord brake line with NAPA brand hose and the bracket was tight but about 5mm away from the right place which made it an awkward fit.

 

I guess you could wrap the hose with rubber and re-install the bracket to snug it down, but it may not be necessary.

[retired1]

The bracket is crimped (clamped) on the line to keep the line from moving. There is not likely any manufacturing company anywhere that will have a particular step in the manufacturing process unless it is necessary, and quite likely required. If the bracket did not have to be clamped firmly around the rubber brake line, the bracket would be made so that it would slip fit on the rubber line, thus eliminating the expense of crimping, clamping, etc. I am not as excited as I may appear about this issue. In the future I will buy rubber brake hoses only from dealerships.

 

Regarding NAPA, in the past they were my first choice for auto parts.... their history suggests they are a very good auto parts store. Perhaps this is why a lot of mechanics prefer getting parts from NAPA stores. Perhaps things are changing. I have noticed that NAPA is now selling parts in plain white boxes with absolutely no printing, marking, etc. on either the white boxes, or the parts. There is absolutely no way to know the country of origin, or the quality, of auto parts that are not marked and that come in plain white boxes. (A Sears tool salesperson recently told me that even Sears is selling some Chinese made tools ..... and having lots of them returned.)

 

OK, enough about that. Back to the problems with my brakes. Thanks. Joe