Brake Washer Replacement And Brake Pedal Going In ?

[eyepea]

Hi,

In my car, one of the rear brake cylinders is leaking a little bit of oil.

No noticeable drop in level of oil in brake oil reservoir.

(rear - drum. front - disk)

Bass said brake washer needs to be replaced. Am yet to take it for repair.

1). If replacing brake washers, have all brake washers (i.e. rear both sides + front both sides + master cylinder) got to be replaced or only washers in leaking cylinder need be replaced ?

2). Has the brake system got to be bled after replacing washers ?

3). In slow breaking (for e.g. applying brake very lightly to gradually slow down for a traffic light some distance away, in a clear road), occasionally, I feel that the brake pedal goes in a little bit.

Let me try to clearly explain it a bit more:

I press the brake pedal lightly, then I feel some resistance / pressure from the pedal. I am not pressing any more because there is no need to slow down the car more.

The resistance / pressure felt from the pedal is the same. Then suddenly I feel the resistance from the pedal drop a little and since I was pressing the pedal, the pedal goes in just a little bit. Then I push down my foot a little bit and I feel the same resistance / pressure from the pedal again.

This happens quickly and as an automatic reaction of the foot and I don't feel as if the car looses any breaking power or the slowing down rate changes at that moment. Of course when there is a car in front it is a teeny weeny bit hair tingling

The actual down movement felt is very little. I did not find it convenient to observe it. Also this issue happens only occasionally. I cannot create the problem at will.

Another thing, in hard breaking (well not necessarily breaking hard to tilt the car forward , but pressing the break more than I described above) did not notice above behaviour yet.

Can this be due to the leaking break cylinder or something else?

Thanks!

[AL998]

1). If replacing brake washers, have all brake washers (i.e. rear both sides + front both sides + master cylinder) got to be replaced or only washers in leaking cylinder need be replaced ?

Only the leaking cylinder has to be replaced ,but make sure the bore of the cylinder has not been damaged otherwise there is no point in changing just the washers

2). Has the brake system got to be bled after replacing washers ?

Yes ,when you open the brake lines you have to bleed out any air inside.

3). In slow breaking (for e.g. applying brake very lightly to gradually slow down for a traffic light some distance away, in a clear road), occasionally, I feel that the brake pedal goes in a little bit.

Let me try to clearly explain it a bit more:

I press the brake pedal lightly, then I feel some resistance / pressure from the pedal. I am not pressing any more because there is no need to slow down the car more.

The resistance / pressure felt from the pedal is the same. Then suddenly I feel the resistance from the pedal drop a little and since I was pressing the pedal, the pedal goes in just a little bit. Then I push down my foot a little bit and I feel the same resistance / pressure from the pedal again.

This happens quickly and as an automatic reaction of the foot and I don't feel as if the car looses any breaking power or the slowing down rate changes at that moment. Of course when there is a car in front it is a teeny weeny bit hair tingling

The actual down movement felt is very little. I did not find it convenient to observe it. Also this issue happens only occasionally. I cannot create the problem at will.

Another thing, in hard breaking (well not necessarily breaking hard to tilt the car forward , but pressing the break more than I described above) did not notice above behaviour yet.

Can this be due to the leaking break cylinder or something else?

Thanks!

If it is the sinking felling you feel when you are braking very gently ,but perfectly OK when you do hard braking

It looks like master pump washers have worn out ,but this can happen if your wheel cylinders are leaking excessively.Since you have mentioned it only a minor leak ,I would suspect the master pump .

You can replace master pump washers but I think these days you can find good second hand parts for cheep.

That's couple of reasons I can think of ,Others may be able add if there is more

Edited September 5, 2010 by AL998

[MkX]

3). In slow breaking (for e.g. applying brake very lightly to gradually slow down for a traffic light some distance away, in a clear road), occasionally, I feel that the brake pedal goes in a little bit.

Let me try to clearly explain it a bit more:

I press the brake pedal lightly, then I feel some resistance / pressure from the pedal. I am not pressing any more because there is no need to slow down the car more.

The resistance / pressure felt from the pedal is the same. Then suddenly I feel the resistance from the pedal drop a little and since I was pressing the pedal, the pedal goes in just a little bit. Then I push down my foot a little bit and I feel the same resistance / pressure from the pedal again.

This happens quickly and as an automatic reaction of the foot and I don't feel as if the car looses any breaking power or the slowing down rate changes at that moment. Of course when there is a car in front it is a teeny weeny bit hair tingling

Not the expert on this and again info is in late 90s in my O/L subject. What I learnt thoese days is that when your car decreases the speed around 10Kmph - 15Kmph ABS stop functioning, and it work as normal breaking system. Means break pads continue to press and against the drum/disk.

When this happens the ABS valves that work to apply/release break will kept open so break will continue to apply. Thus it will reduce resistance to break pedal and you can feel it to you foot as pedal goes down around 1cm.

BTW, does any of you feel this ABS open and close to you foot in sudden de-acceleration?

Edited September 6, 2010 by MkX

[eyepea]

thanks guys.

It looks like master pump washers have worn out

uh this is scary.

wishfully thinking it perhaps be ABS explanation

If master pump washers give way, I guess then breaks will not work

Hope this is a gradual thingy and doesn't happen suddenly ?.

long time back dad's car master clutch cylinder washers gave way and clutch went in fully while driving. Of course a little going-in of the pedal was noticed earlier. Well that happening to clutch is no major issue. But I wouldn't want that for the break pedal!.

[AL998]

thanks guys.

uh this is scary.

wishfully thinking it perhaps be ABS explanation

If master pump washers give way, I guess then breaks will not work

Hope this is a gradual thingy and doesn't happen suddenly ?.

long time back dad's car master clutch cylinder washers gave way and clutch went in fully while driving. Of course a little going-in of the pedal was noticed earlier. Well that happening to clutch is no major issue. But I wouldn't want that for the break pedal!.

When the internal washers or O-rings worn out ,you can get the above symptoms .Since it is leaking internally from one chamber to a another chamber you will not see any external leak .

if the seals are worn slightly then you will not notice it when you brake hard ,but will get the sinking feeling when you brake softly

[AL998]

thanks guys.

uh this is scary.

wishfully thinking it perhaps be ABS explanation

If master pump washers give way, I guess then breaks will not work

Hope this is a gradual thingy and doesn't happen suddenly ?.

long time back dad's car master clutch cylinder washers gave way and clutch went in fully while driving. Of course a little going-in of the pedal was noticed earlier. Well that happening to clutch is no major issue. But I wouldn't want that for the break pedal!.

read this ,it will give you a good explanation

brakes

Master Cylinder

The master cylinder is located in the engine compartment on the firewall, directly in front of the driver's seat. A typical master cylinder is actually two completely separate master cylinders in one housing, each handling two wheels. This way if one side fails, you will still be able to stop the car. The brake warning light on the dash will light if either side fails, alerting you to the problem. Master cylinders have become very reliable and rarely malfunction; however, the most common problem that they experience is an internal leak. This will cause the brake pedal to slowly sink to the floor when your foot applies steady pressure. Letting go of the pedal and immediately stepping on it again brings the pedal back to normal height.

Edited September 6, 2010 by AL998

[Elvis_Pil]

1. Change all the washers- if one's gone the others cant be too far away- and you dont want to take a chance on break related stuff

2. Yes- get it done with a place that uses a machine, rather than the manual 'press the peddle' and bleed method- which has a likelihood of letting bubbles into the system.

3.This is related to you're original issue, the leak causes a drop in pressure in the whole break system, which maybe the reason you get the soft feeling when pressing the peddle down

Hi,

In my car, one of the rear brake cylinders is leaking a little bit of oil.

No noticeable drop in level of oil in brake oil reservoir.

(rear - drum. front - disk)

Bass said brake washer needs to be replaced. Am yet to take it for repair.

1). If replacing brake washers, have all brake washers (i.e. rear both sides + front both sides + master cylinder) got to be replaced or only washers in leaking cylinder need be replaced ?

2). Has the brake system got to be bled after replacing washers ?

3). In slow breaking (for e.g. applying brake very lightly to gradually slow down for a traffic light some distance away, in a clear road), occasionally, I feel that the brake pedal goes in a little bit.

Let me try to clearly explain it a bit more:

I press the brake pedal lightly, then I feel some resistance / pressure from the pedal. I am not pressing any more because there is no need to slow down the car more.

The resistance / pressure felt from the pedal is the same. Then suddenly I feel the resistance from the pedal drop a little and since I was pressing the pedal, the pedal goes in just a little bit. Then I push down my foot a little bit and I feel the same resistance / pressure from the pedal again.

This happens quickly and as an automatic reaction of the foot and I don't feel as if the car looses any breaking power or the slowing down rate changes at that moment. Of course when there is a car in front it is a teeny weeny bit hair tingling

The actual down movement felt is very little. I did not find it convenient to observe it. Also this issue happens only occasionally. I cannot create the problem at will.

Another thing, in hard breaking (well not necessarily breaking hard to tilt the car forward , but pressing the break more than I described above) did not notice above behaviour yet.

Can this be due to the leaking break cylinder or something else?

Thanks!

Edited September 7, 2010 by Elvis_Pil

[eyepea]

Thanks very much for the info and advice.

(Sorry to bring up old topic now. could not log in to AL for quite some time)

update:

Break washers were replaced to solve the leak.

But the occasional pedal going in a bit on slow breaking is still there.

Got a couple of places to check it out, but the mechanics who test drove could not feel it.

So was advised to bring car if problem gets more.