Break pedal sinking / break fluind leakage possible

someboy0 · 3rd November 2009, 15:23

I've had a look at the past posts and threads on here to try to see if there is a sollution but couldn't find so I thought I could make a new thread.

So, the problem is as follows. With the engine running, if you press the break pedal hard it goes to a certain point and than starts to slowly depress further, apparently that is nothing to worry on its own BUT, the break fluid seems to magically dissapear as well somewhere and I don't know where because I can't see it under the car or on the insides of the wheels, the servo is working fine (I assume from what I've read about what it's suposed to do etc. I'm not a mechanic and have a very small techincal knowledge) so could it be the break master cylinder? Maybe some of the things that the fluid goes through are leaking? Any ideas? I've read somewhere that if it would be leaking into the servo than a smoke would be comming out of the exchaust, and that is not happening. I don't know how long ago the break fluid was changed but my guess would be over 2 years ago but as it's leaking somewhere at the moment I can't see a point in changing it right now cause at the moment we have to just put some more in when we want to drive the car which we don't since we detected the fault, also the breaking performance has decreased.

It is a Rover 75 W reg 2.5 V6

Any kind of reply would be greatly appreciated, thanks in advance.

T-Cut · 3rd November 2009, 16:43

I guess you're talking about the Sinking Pedal Phenomenon (SPP) as I call it. This is a well known effect and is broadly regarded as normal behaviour. Some people associate it with flipped seals in the master cylinder, but since it only happens when the engine's running and the car stationary, I believe it's a system control effect. The braking control system involves road speed, wheel speed and pedal pressure to determine what happens with the hydraulic pressure. Under the conditions SPP happens, I believe the fluid is simply recycled in the master cylinder. So, there is no loss or leakeage. If you check the level regularly, you should have nothing to worry about regarding SPP.

You can read the previous discussions on the subject by seaching for "SPP" (include the quotes).

TC

someboy0 · 3rd November 2009, 16:59

Thank you for your responce, I will take a look at other threads about SSP like you suggested right now but assuming that the fluid is recycled in the master cylinder wouldn't the break fluid level remain stable after some time? I mean when we stopped at a petrol station after my dad noticed that something seems to be wrong and the car isn't breaking as well as it should've he bought the break fluid topped up it to max in the reservior, he than pressed the break pedal a few times with the engine runnig but the car being stationary and the fluid level dropped and as far as I've seen the master cylinder is reasonably small so I imagine that much of that fluid can't be recycled in there, anyway I'll have a look at other threads now regarding the SSP and see what people say.

Just one question though, last time the car went for diagnostics (engine work was done) the mechanic told us that the break pads will need to be replaced in the front, the car is fitted with sensors which allert you when the pads need to be replaced, is it likely that the sensoers are broken and the break pads should be replaced some time ago and the lower breaking performance would be than related to worn break pads? I hope you don't mind me asking all these questions but my dad is getting slowly fed up with paying for the car and since we bought the car in about february this year there was engine work for about 1700 than clutch and dual mass flywheel replacement for about 1200 and now this so I guess you can kind of imagine

Big thanks for your help.

someboy0 · 3rd November 2009, 17:33

I've had a look at other posts about SPP and I came across a few posts about master cylinder seals, if these are broken would the break fluid leak somewhere outside the car and thus be visible on the ground under the car or would it leak in a place where we wouln't be able to notice it, and from what I've seen lowering level of break fluid isn't associated with the SPP as far as I gathered, you said about it being recycled in the master cylinder but would it be the case that at some point the master cylinder will just fill up and the break fluid level should remain at max level? Please forgive me for possible obvious questions but my knowledge about this stuff is very limited.

David

[EDIT]
Also I just realised it might be worth mentioning that the car has done over 150 000 miles - mainly motorway

chris75 · 3rd November 2009, 19:17

From your account , you do indeed appear to have a leak somewhere .How hard have you looked for it so far ? The chief suspects would be :

the calipers - you need to take off each wheel to look for leakage,

the reservoir/master - remove the trim over the bulkhead as if you were going to top it up again and shine a torch down into the space below ,also check the carpets under the pedals .

the brake pipes from front to back - these run along the underside of the body , visible from the drivers side , and are very prone to corrosion.

This is a starter................

Departed · 3rd November 2009, 19:26

Quote:

Originally Posted by T-Cut

I guess you're talking about the Sinking Pedal Phenomenon (SPP) as I call it. This is a well known effect and is broadly regarded as normal behaviour. Some people associate it with flipped seals in the master cylinder, but since it only happens when the engine's running and the car stationary, I believe it's a system control effect. The braking control system involves road speed, wheel speed and pedal pressure to determine what happens with the hydraulic pressure. Under the conditions SPP happens, I believe the fluid is simply recycled in the master cylinder. So, there is no loss or leakeage. If you check the level regularly, you should have nothing to worry about regarding SPP.

You can read the previous discussions on the subject by seaching for "SPP" (include the quotes).

TC

I wouldn't say 'normal behaviour' . Neither of my cars do it (funnily enough I double checked mine this evening), and nor has any other car I've driven including a few other makes with the same ABS.

I'm also fairly certain that there's no pedal / fluid pressure monitoring on this system. Certainly I've not seen the pressure sensor which is normally screwed into the side of the modulator valve block. I would think it only happens with the engine running because of the extra assistance from the servo.

I'd also point out the OP says he is losing fluid, so I don't think it's SPP anyway.

3disco · 3rd November 2009, 19:55

If no external leaks ,check the carpet were the brake rod goes into the master cylinder for brake fluid, and then if none found probably losing it into servo.

T-Cut · 3rd November 2009, 20:21

The OP does seem to have a hydraulic leak. The general tenure of the original query seemed to be about pedal sink, but if fluid is being lost from the reservoir, then that's a serious matter. As noted, the original steel pipes are of poor stuff and corrode like fury if not treated early enough. I'd suggest the car should be taken to a garage for a proper under body inspection and pipe replacement as necessay.

TC

someboy0 · 3rd November 2009, 23:20

I will try to find the pipes you are talking about, I'll do the torch check and the rest you advised, I spoke to the garage that did the clutch and the engine work on this car and they told me to bring it in and they will have a look at it but the car now also needs an MOT and my dad insists that if there is something to be done that the garage which will be doing the MOT will take care of the problem BUT the garage that did the previous work on the car doesn't do MOTs so it's kinda complicated but I'll do as many checks as possible from what you've said, I won't be taking the wheels off cause I'm really bad at technical stuff and I don't want to risk doing something wrong when it comes to wheels. I think I will pay the garage a quick visit tomorrow with my dad but do any of you know what kind of cost I might be looking at with lets say servo / master cylinder / pipes replacement? I guess the parts won't cost that much but labour wise is it costly ? Because I wouldn't be doing these things myself neither would be my dad and it would be nice to know if it's gonna go near the 1000 if either of the things have to be replaced which probably is the case. I will let you know how things are developing.
Thank you very much guys for your responce!

David

[EDIT]
What does OP stand for ?

Departed · 4th November 2009, 07:05

OP= Original Poster.

How much it will cost depends very much on what the problem is. For example, if it's a brake pipe, then it could be front or rear. The front left hand one is short and easy to change, the rear left is the longest and is a complete pig. Parts for this will not be expensive, but pig jobs take time which equals money.

Has he had the car long, as I remember another member who had a pipe replaced, and the joint was not properly made on the ABS modulator, as the garage cross threaded the fitting. This is not visible as it's under the battery tray.

3rd November 2009, 15:23	#1
someboy0 Loves to post Rover 75 Connoisseur SE 2.5 V6 Join Date: Feb 2009 Location: Manchester Posts: 314 Thanks: 0 Thanked 0 Times in 0 Posts	Break pedal sinking / break fluind leakage possible I've had a look at the past posts and threads on here to try to see if there is a sollution but couldn't find so I thought I could make a new thread. So, the problem is as follows. With the engine running, if you press the break pedal hard it goes to a certain point and than starts to slowly depress further, apparently that is nothing to worry on its own BUT, the break fluid seems to magically dissapear as well somewhere and I don't know where because I can't see it under the car or on the insides of the wheels, the servo is working fine (I assume from what I've read about what it's suposed to do etc. I'm not a mechanic and have a very small techincal knowledge) so could it be the break master cylinder? Maybe some of the things that the fluid goes through are leaking? Any ideas? I've read somewhere that if it would be leaking into the servo than a smoke would be comming out of the exchaust, and that is not happening. I don't know how long ago the break fluid was changed but my guess would be over 2 years ago but as it's leaking somewhere at the moment I can't see a point in changing it right now cause at the moment we have to just put some more in when we want to drive the car which we don't since we detected the fault, also the breaking performance has decreased. It is a Rover 75 W reg 2.5 V6 Any kind of reply would be greatly appreciated, thanks in advance.

3rd November 2009, 16:43	#2
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,753 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	I guess you're talking about the Sinking Pedal Phenomenon (SPP) as I call it. This is a well known effect and is broadly regarded as normal behaviour. Some people associate it with flipped seals in the master cylinder, but since it only happens when the engine's running and the car stationary, I believe it's a system control effect. The braking control system involves road speed, wheel speed and pedal pressure to determine what happens with the hydraulic pressure. Under the conditions SPP happens, I believe the fluid is simply recycled in the master cylinder. So, there is no loss or leakeage. If you check the level regularly, you should have nothing to worry about regarding SPP. You can read the previous discussions on the subject by seaching for "SPP" (include the quotes). TC Last edited by T-Cut; 3rd November 2009 at 16:45..

3rd November 2009, 17:33	#4
someboy0 Loves to post Rover 75 Connoisseur SE 2.5 V6 Join Date: Feb 2009 Location: Manchester Posts: 314 Thanks: 0 Thanked 0 Times in 0 Posts	I've had a look at other posts about SPP and I came across a few posts about master cylinder seals, if these are broken would the break fluid leak somewhere outside the car and thus be visible on the ground under the car or would it leak in a place where we wouln't be able to notice it, and from what I've seen lowering level of break fluid isn't associated with the SPP as far as I gathered, you said about it being recycled in the master cylinder but would it be the case that at some point the master cylinder will just fill up and the break fluid level should remain at max level? Please forgive me for possible obvious questions but my knowledge about this stuff is very limited. David [EDIT] Also I just realised it might be worth mentioning that the car has done over 150 000 miles - mainly motorway __________________ Rover 75 - The car with a soul Last edited by someboy0; 3rd November 2009 at 17:35..

3rd November 2009, 19:17	#5
chris75 same car since 2005 2001 Rover 75 2.0 v6 Connoisseur Saloon Join Date: Nov 2006 Location: Ellesmere Port , Cheshire Posts: 3,811 Thanks: 379 Thanked 549 Times in 466 Posts	From your account , you do indeed appear to have a leak somewhere .How hard have you looked for it so far ? The chief suspects would be : the calipers - you need to take off each wheel to look for leakage, the reservoir/master - remove the trim over the bulkhead as if you were going to top it up again and shine a torch down into the space below ,also check the carpets under the pedals . the brake pipes from front to back - these run along the underside of the body , visible from the drivers side , and are very prone to corrosion. This is a starter................ __________________ Who said it was simples ?

3rd November 2009, 19:55	#7
3disco 3disco ROVER 75 CONN TOURER CDTI and ZTT V8 SE LPG Join Date: Sep 2008 Location: chardstock.axminster,devon Posts: 1,493 Thanks: 361 Thanked 94 Times in 85 Posts	Servo If no external leaks ,check the carpet were the brake rod goes into the master cylinder for brake fluid, and then if none found probably losing it into servo.

3rd November 2009, 16:59	#3
someboy0 Loves to post Rover 75 Connoisseur SE 2.5 V6 Join Date: Feb 2009 Location: Manchester Posts: 314 Thanks: 0 Thanked 0 Times in 0 Posts	Thank you for your responce, I will take a look at other threads about SSP like you suggested right now but assuming that the fluid is recycled in the master cylinder wouldn't the break fluid level remain stable after some time? I mean when we stopped at a petrol station after my dad noticed that something seems to be wrong and the car isn't breaking as well as it should've he bought the break fluid topped up it to max in the reservior, he than pressed the break pedal a few times with the engine runnig but the car being stationary and the fluid level dropped and as far as I've seen the master cylinder is reasonably small so I imagine that much of that fluid can't be recycled in there, anyway I'll have a look at other threads now regarding the SSP and see what people say. Just one question though, last time the car went for diagnostics (engine work was done) the mechanic told us that the break pads will need to be replaced in the front, the car is fitted with sensors which allert you when the pads need to be replaced, is it likely that the sensoers are broken and the break pads should be replaced some time ago and the lower breaking performance would be than related to worn break pads? I hope you don't mind me asking all these questions but my dad is getting slowly fed up with paying for the car and since we bought the car in about february this year there was engine work for about 1700 than clutch and dual mass flywheel replacement for about 1200 and now this so I guess you can kind of imagine Big thanks for your help.

3rd November 2009, 20:21	#8
T-Cut This is my second home Rover75 and Mreg Corsa. Join Date: Nov 2006 Location: Sumweer onat mote o'dust (Sagin) Posts: 21,753 Thanks: 341 Thanked 3,660 Times in 2,924 Posts	The OP does seem to have a hydraulic leak. The general tenure of the original query seemed to be about pedal sink, but if fluid is being lost from the reservoir, then that's a serious matter. As noted, the original steel pipes are of poor stuff and corrode like fury if not treated early enough. I'd suggest the car should be taken to a garage for a proper under body inspection and pipe replacement as necessay. TC

3rd November 2009, 23:20	#9
someboy0 Loves to post Rover 75 Connoisseur SE 2.5 V6 Join Date: Feb 2009 Location: Manchester Posts: 314 Thanks: 0 Thanked 0 Times in 0 Posts	I will try to find the pipes you are talking about, I'll do the torch check and the rest you advised, I spoke to the garage that did the clutch and the engine work on this car and they told me to bring it in and they will have a look at it but the car now also needs an MOT and my dad insists that if there is something to be done that the garage which will be doing the MOT will take care of the problem BUT the garage that did the previous work on the car doesn't do MOTs so it's kinda complicated but I'll do as many checks as possible from what you've said, I won't be taking the wheels off cause I'm really bad at technical stuff and I don't want to risk doing something wrong when it comes to wheels. I think I will pay the garage a quick visit tomorrow with my dad but do any of you know what kind of cost I might be looking at with lets say servo / master cylinder / pipes replacement? I guess the parts won't cost that much but labour wise is it costly ? Because I wouldn't be doing these things myself neither would be my dad and it would be nice to know if it's gonna go near the 1000 if either of the things have to be replaced which probably is the case. I will let you know how things are developing. Thank you very much guys for your responce! David [EDIT] What does OP stand for ? __________________ Rover 75 - The car with a soul

4th November 2009, 07:05	#10
Departed Retired -- Join Date: Jan 2007 Location: -- Posts: 3,785 Thanks: 0 Thanked 4 Times in 4 Posts	OP= Original Poster. How much it will cost depends very much on what the problem is. For example, if it's a brake pipe, then it could be front or rear. The front left hand one is short and easy to change, the rear left is the longest and is a complete pig. Parts for this will not be expensive, but pig jobs take time which equals money. Has he had the car long, as I remember another member who had a pipe replaced, and the joint was not properly made on the ABS modulator, as the garage cross threaded the fitting. This is not visible as it's under the battery tray.