93 Civic D15B brake issue
05-03-2015, 10:07 AM
#1
Hysterically Calm
Thread Starter
93 Civic D15B brake issue
Looking at this testing procedure:
The very first functional test of pumping the brakes multiple times with engine off and then pressing the brakes, the brake pedal never went down. Acted rock solid.
Then while still holding the brake strongly, start the car, the brake pedal sinks to the floor rather fluidly and quickly.
Pumping the brakes rapidly with the engine running increased idle but only a little, not as much as I was used to.
Pulling the brake booster hose from the IM there is strong vacuum, Pulling the hose from the brake booster (after check valve) there is vacuum just not as strong.
Also visual evidence on the MC and Booster, the paint is pealing off of the booster around the side edges of the MC and all the way down to the bottom of the booster under the MC.
I would hazard a guess the MC sprung a pretty decent leak and the booster was not replaced or cleaned up after the MC was replaced.
With the car off, the brake pedal depresses the farthest the first push and less and less each press after until it's maxed out and stays solid. I can hear the rare pads clamping and releasing.
I held the brake pedal hard with the car off for at least one solid minute with no change.
The pedal only drops to the floor with the car running.
Does this still sound like a master cylinder?
What is the behavior of a booster with a deteriorated diaphragm?
Functional Test
1. With the engine off, press the brake pedal several times to deplete the vacuum reservoir, then firmly press-and-hold the brake pedal for 15 seconds. If the brake pedal sinks, either the MC is internally bypassing, or there is a leak in the brake system. (mc, lines, prop valve, calipers, wheel cylinders, etc)
2. With the brake pedal pressed, start the engine. If the pedal sinks slightly, the vacuum booster is okay. However, if the brake pedal height does not vary, the check valve or booster is faulty.
3. With the engine running, lightly press the brake pedal. If the pedal sinks more than 3/8" (10mm) in three minutes, the master cylinder is faulty. (If the A/C is on, a slight change in the height of the brake pedal is normal.)
Leak Test
1. With the engine running, press-and-hold the brake pedal, then turn the engine off. If the pedal height does not vary while pressed for 30 seconds, the vacuum booster is okay. If the brake pedal rises, the booster is bad.
2. Turn the engine off and wait for about 30 seconds. Press the brake pedal several times using normal pressure. When the brake pedal is first pressed, it should be low, then gradually rise with each consecutive compression. If the position of the pedal does not vary, inspect the booster check valve.
3. Disconnect the vacuum hose (check valve built-in) at the brake booster.
4. Start the engine and let it idle. There should be vacuum available. If there is no vacuum, the check valve is not functioning properly. Replace the vacuum hose, and retest.
5. With the engine running, pinch the vacuum hose between the check valve and the booster.
6. Turn the engine off and wait for about 30 seconds. Press the brake pedal several times using normal pressure. Again, the brake pedal should be low when it's first pressed, gradually rising with each consecutive compression. If the pedal position does not vary, replace the booster. If the pedal position does vary, replace the vacuum hose / check valve assembly.
1. With the engine off, press the brake pedal several times to deplete the vacuum reservoir, then firmly press-and-hold the brake pedal for 15 seconds. If the brake pedal sinks, either the MC is internally bypassing, or there is a leak in the brake system. (mc, lines, prop valve, calipers, wheel cylinders, etc)
2. With the brake pedal pressed, start the engine. If the pedal sinks slightly, the vacuum booster is okay. However, if the brake pedal height does not vary, the check valve or booster is faulty.
3. With the engine running, lightly press the brake pedal. If the pedal sinks more than 3/8" (10mm) in three minutes, the master cylinder is faulty. (If the A/C is on, a slight change in the height of the brake pedal is normal.)
Leak Test
1. With the engine running, press-and-hold the brake pedal, then turn the engine off. If the pedal height does not vary while pressed for 30 seconds, the vacuum booster is okay. If the brake pedal rises, the booster is bad.
2. Turn the engine off and wait for about 30 seconds. Press the brake pedal several times using normal pressure. When the brake pedal is first pressed, it should be low, then gradually rise with each consecutive compression. If the position of the pedal does not vary, inspect the booster check valve.
3. Disconnect the vacuum hose (check valve built-in) at the brake booster.
4. Start the engine and let it idle. There should be vacuum available. If there is no vacuum, the check valve is not functioning properly. Replace the vacuum hose, and retest.
5. With the engine running, pinch the vacuum hose between the check valve and the booster.
6. Turn the engine off and wait for about 30 seconds. Press the brake pedal several times using normal pressure. Again, the brake pedal should be low when it's first pressed, gradually rising with each consecutive compression. If the pedal position does not vary, replace the booster. If the pedal position does vary, replace the vacuum hose / check valve assembly.
Then while still holding the brake strongly, start the car, the brake pedal sinks to the floor rather fluidly and quickly.
Pumping the brakes rapidly with the engine running increased idle but only a little, not as much as I was used to.
Pulling the brake booster hose from the IM there is strong vacuum, Pulling the hose from the brake booster (after check valve) there is vacuum just not as strong.
Also visual evidence on the MC and Booster, the paint is pealing off of the booster around the side edges of the MC and all the way down to the bottom of the booster under the MC.
I would hazard a guess the MC sprung a pretty decent leak and the booster was not replaced or cleaned up after the MC was replaced.
With the car off, the brake pedal depresses the farthest the first push and less and less each press after until it's maxed out and stays solid. I can hear the rare pads clamping and releasing.
I held the brake pedal hard with the car off for at least one solid minute with no change.
The pedal only drops to the floor with the car running.
Does this still sound like a master cylinder?
What is the behavior of a booster with a deteriorated diaphragm?
05-03-2015, 11:32 AM
#2
Hysterically Calm
Thread Starter
Re: 93 Civic D15B brake issue
Watching this video basically demonstrated the same behavior I witnessed:
This tells me the brake booster and check valve are fine and it is indeed the master cylinder that is my problem.
The confusing part is, I thought if the master cylinder was leaking that with the car off and consistent pressure on the pedal, the pedal would start to drop.
This vehicle does not do that no matter how much pressure you put nor how long you hold the pedal. With the car off, the pedal becomes pretty solid and does not lose any pedal height no matter how long or how hard I press the pedal.
This tells me the brake booster and check valve are fine and it is indeed the master cylinder that is my problem.
The confusing part is, I thought if the master cylinder was leaking that with the car off and consistent pressure on the pedal, the pedal would start to drop.
This vehicle does not do that no matter how much pressure you put nor how long you hold the pedal. With the car off, the pedal becomes pretty solid and does not lose any pedal height no matter how long or how hard I press the pedal.
05-03-2015, 02:10 PM
#5
Hysterically Calm
Thread Starter
Re: 93 Civic D15B brake issue
I do know my wife just reported this behavior, it was acting normal two weeks ago and just started "feeling funny" as she put it.
I know the wheel cylinders are not leaking as I just tore that area apart. I also don't notice any pooling of brake fluid on the front wheels so if the calipers are leaking it's very slight if at all.
The brake MC and booster are dry as well as all the lines you can see in the engine bay. Also the fluid hasn't gone down significantly nor has the parking brake light come on for low reservoir.
I just went and pulled a used MC from the salvage yard, the push pin was dry (first one had brake fluid so was already leaking into the booster).
I suspect my wifes MC is probably also leaking into the the booster too and just started a little over a week ago.
Yesterday was the first I drove it after she mentioned her brakes didn't feel normal as of late. So I sat down and did most of the tests It Wasn't Me posted and then also tried the brake pedal solid and for long duration without the motor running.
The brakes still work but not with the same force unless you pump them but even then once you switch to solid pressure the pedal sinks to the floor.
Every post I found repeatedly says MC. So that's my first step as it doesn't seem to be the booster as per the video. Oh and I didn't find any evidence of leaking even though I need to check a couple of other spots to be sure.
I'll check the front calipers today just for grins and giggles.
Last edited by TomCat39; 05-03-2015 at 05:22 PM. Reason: part name correction in red
05-01-2017, 05:39 PM
#6
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Re: 93 Civic D15B brake issue
Have you found you problem??
my 07 honda odyssey does exactly the same thing
I did replace the mc with no change
Bleed the system many times no air coming out
Only does it with the engine on just like yours
my 07 honda odyssey does exactly the same thing
I did replace the mc with no change
Bleed the system many times no air coming out
Only does it with the engine on just like yours
05-01-2017, 06:45 PM
#7
Re: 93 Civic D15B brake issue
#1 is incorrect. You want to pump the brakes and then lightly press the brake pedal, less pressure the better. If you apply firm pressure you are expanding the seals inside the master. You want to check for fluid leak past the seals to determine if they are worn. If you apply heavy pressure, you will only find a failure when it is very worn. Finding a failure earlier is better than later, so apply light pressure.
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05-01-2017, 07:15 PM
#8
Re: 93 Civic D15B brake issue
Pedal hits the floor but the car does not stop, means air in the lines or bad MC. Clearly you're not lacking power from the booster.
Blown diaphragm in the booster causes no power brakes (hard to stop, but pedal does not go to the floor) while a lot of air goes into the engine (steadily increased idle speed) when the pedal is pressed. This will happen eventually if brake fluid got into the booster.
Blown diaphragm in the booster causes no power brakes (hard to stop, but pedal does not go to the floor) while a lot of air goes into the engine (steadily increased idle speed) when the pedal is pressed. This will happen eventually if brake fluid got into the booster.
05-01-2017, 07:46 PM
#9
Hysterically Calm
Thread Starter
Re: 93 Civic D15B brake issue
Pedal hits the floor but the car does not stop, means air in the lines or bad MC. Clearly you're not lacking power from the booster.
Blown diaphragm in the booster causes no power brakes (hard to stop, but pedal does not go to the floor) while a lot of air goes into the engine (steadily increased idle speed) when the pedal is pressed. This will happen eventually if brake fluid got into the booster.
Blown diaphragm in the booster causes no power brakes (hard to stop, but pedal does not go to the floor) while a lot of air goes into the engine (steadily increased idle speed) when the pedal is pressed. This will happen eventually if brake fluid got into the booster.
It's much better for pedal resistance but still not as solid as my car.
Car always stopped okay, just the pedal would slowly drop to the floor if you held significant pressure on the pedal.
I think the replaced MC is better but still not perfectly solid.
Glad to have confirmation that it's not the booster.
I don't think I can lock up the brakes on her car yet but I haven't truly tested as she's in the car when I drive it and doesn't like going at a good clip and hammering the brakes.
I should take it out and test that before jumping to conclusions.
05-02-2017, 04:33 AM
#10
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Re: 93 Civic D15B brake issue
I m going for a second MC to see what happens
Here's one tip that may cause the problem
When i installed the MC it came with a tool to adjust the lenght of the booster rod
I couldn't do it because didn't have the tool so i put it on without adjusting
somebody know if a wrong adjustment of the booster push rod (mine is a little far out than it should be ) could cause the pedal to go to the floor with the engine on only??
Here's one tip that may cause the problem
When i installed the MC it came with a tool to adjust the lenght of the booster rod
I couldn't do it because didn't have the tool so i put it on without adjusting
somebody know if a wrong adjustment of the booster push rod (mine is a little far out than it should be ) could cause the pedal to go to the floor with the engine on only??
05-02-2017, 04:44 AM
#11
Re: 93 Civic D15B brake issue
No.
If the push rod is too long, the brakes will not fully release, and they will start to drag after driving for a few miles. If it is too short, there will be excessive slack before the brakes start to engage, but the car should still stop.
If the push rod is too long, the brakes will not fully release, and they will start to drag after driving for a few miles. If it is too short, there will be excessive slack before the brakes start to engage, but the car should still stop.
05-02-2017, 05:16 AM
#12
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Re: 93 Civic D15B brake issue
My car stop but i have to push the break pedal pretty hard
when the engine is on if you put constant pressure it goes all the way to the floor . doesn't do it with engine off
There's no air or leaks in the system fluid level always the same no drag after driving for a while
Feels to me like for some reason the first part on the MC which i believe is the front breakes is not pressurizing the way it should
I may be wrong please advise
Thanks
when the engine is on if you put constant pressure it goes all the way to the floor . doesn't do it with engine off
There's no air or leaks in the system fluid level always the same no drag after driving for a while
Feels to me like for some reason the first part on the MC which i believe is the front breakes is not pressurizing the way it should
I may be wrong please advise
Thanks
05-02-2017, 08:09 PM
#13
Hysterically Calm
Thread Starter
Re: 93 Civic D15B brake issue
This was one time I didn't study the FSM before swapping the part and my MC might be a bit out of adjustment on the loose side.
Will keep this on the books and once we move will look into getting Honda part number 07JAG-SD40100 so I can calibrate the push rod.
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